JP2021180085A - Method of activating fuel cell stack - Google Patents

Abstract

To provide a method for activating a fuel cell stack that can uniformly age the insides of fuel battery cells.SOLUTION: A fuel cell stack 115 in which fuel battery cells 115C are stacked, and a control unit 101 for controlling the state of the fuel cell stack 115 are provided. The control unit 101 executes a first step of causing the fuel cell stack 115 to generate electric power, and supplying the generated electric power to a load, and a second step of suspending the power generation of the fuel battery cells 115C included in the fuel cell stack 115. The air stoichiometric ratio on the cathode side in the first step is set within a range where the hydrogen adsorption/desorption potential of a catalyst can be used.SELECTED DRAWING: Figure 1

Description

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

The 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 bonded to both sides of the electrolyte membrane. Further, separators provided with gas flow paths are arranged on both sides of the membrane electrode gas diffusion layer joint body. Then, a fuel cell stack in which a plurality of fuel cell cells including such MEGA and a separator are laminated is configured.

The manufactured fuel cell stack may not have sufficient performance as specified due to insufficient water content in the electrolyte membrane and the electrolyte in the catalyst layer, adhesion of foreign matter to the catalyst surface, oxidation of the catalyst, and the like. Therefore, it is necessary to age and activate the fuel cell stack so that the specified performance can be obtained by optimizing the water content in the electrolyte membrane and the electrolyte in the catalyst layer, removing foreign substances on the catalyst surface, and reducing the catalyst. There is. This aging is proposed in Patent Document 1 below.

Japanese Unexamined Patent Publication No. 2016-35910

In Patent Document 1, in order to remove impurity ions adsorbed on the catalyst surface, fuel is supplied to the membrane electrode gas diffusion layer junction while the oxidant gas is circulated in a sealed air circulation path. It has been proposed to keep the generated voltage of the battery stack below 0.3V. In order to perform this aging, it is necessary to pass a large current through the load in order to reduce the generated voltage to 0.3 V or less.

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

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

This disclosure has been made in view of the above problems, and an object of the present invention is to provide a method for activating a fuel cell stack capable of uniformly aging the inside of a fuel cell.

The method for activating the fuel cell stack according to this disclosure includes a fuel cell stack in which fuel cell cells that are supplied with oxygen-containing air and hydrogen to generate electricity are stacked, a control unit that controls the state of the fuel cell stack, and a control unit. The control unit executes a first step of causing the fuel cell to generate electricity and supplying the generated power to the load, and a second step of suspending the power generation of the fuel cell, and the cathode in the first step. Set the air stoichiometric ratio on the side to a range where the hydrogen adsorption / desorption potential of the catalyst can be used.

In the first step, the control unit causes the fuel cell stack to generate electricity so that the fuel cell cells generate the maximum current.
The control unit sets the air stoichiometric ratio to 1.1 to 1.4 in the first step.

The control unit adjusts the amount of air supplied to the fuel cell stack and the amount of hydrogen, and sets the differential pressure between the electrodes so that the pressure on the anode side becomes larger than the pressure on the cathode side.

The control unit is set so that the hydrogen stoichiometric ratio on the anode side does not become smaller than 1 in the first step.

It is equipped with a radiator that absorbs the heat generated in the fuel cell by the cooling medium and releases the absorbed heat to the outside of the fuel cell, and the control unit is in the radiator so that the temperature of the fuel cell does not exceed the set value. Control the release of heat.

A temperature control unit that adjusts the temperature of hydrogen and air is further provided, and the control unit is a temperature control unit that makes the temperature of hydrogen and air passing through the piping supplied to the fuel cell stack higher than the dew point temperature in the fuel cell. To control.

According to the method for activating the fuel cell stack according to the present disclosure, the inside of the fuel cell can be uniformly aged.

It is a block diagram which shows the structure of the fuel cell system to which Embodiment 1 is applied. It is explanatory drawing which shows the structure of the fuel cell and the current density at the time of power generation in Embodiment 1. FIG. It is explanatory drawing which shows the structure of the fuel cell and the current density at the time of power generation in Embodiment 1. FIG. It is a characteristic figure which shows the characteristic of the hydrogen stoichiometric ratio on the anode side and the standard deviation of the current density at the time of aging of the fuel cell stack in Embodiment 1. FIG. FIG. 5 is a characteristic diagram showing the characteristics of the air stochastic ratio on the cathode side and the standard deviation of the current density during aging of the fuel cell stack according to the first embodiment. It is a characteristic diagram which shows the cell voltage-current characteristic at the time of aging of the fuel cell stack in Embodiment 1. FIG. It is a characteristic figure which shows the characteristic of the anode inlet pressure and the standard deviation of the current density at the time of aging of the fuel cell stack in Embodiment 1. FIG. It is a characteristic figure which shows the characteristic of the cathode outlet pressure and the standard deviation of the current density at the time of aging of the fuel cell stack in Embodiment 1. FIG. It is a block diagram which shows the other configuration of the fuel cell system to which Embodiment 1 is applied.

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

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

[Fuel cell system configuration]
The fuel cell system 100 shown in FIG. 1 includes a control unit 101, a hydrogen tank 112, a compressor 113, a hydrogen supply valve 114, a fuel cell stack 115, a DCDC conversion unit 116, a power storage device 117, and a radiator 118. And have. The fuel cell stack 115 is provided with a measuring unit 115s. The radiator 118 is provided with a measuring unit 118s.

The control unit 101 controls the state of the fuel cell stack 115 by performing various controls related to the power generation of the fuel cell system 100 and controlling the aging of the fuel cell stack 115. Aging is a specification of the fuel cell stack 115 by optimizing the water content of the electrolyte film and the electrolyte in the catalyst layer contained in the fuel cell cells constituting the fuel cell stack 115, removing foreign substances on the catalyst surface, and reducing the catalyst. It is the work to obtain the performance of. This aging is sometimes referred to as activation treatment.

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, and the amount of hydrogen gas supplied from the hydrogen tank 112 to the fuel cell stack 115 is adjusted. The compressor 113 supplies oxygen-containing air to the 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 is configured by a stack structure in which a plurality of fuel cell cells for power generation are stacked. In the fuel cell stack 115, each fuel cell cell generates electricity based on the control of the control unit 101 by hydrogen from the hydrogen tank 112 via the hydrogen supply valve 114 and oxygen contained in the air from the compressor 113.

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

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

The radiator 118 circulates in the cooling medium circulation system of each fuel cell in the fuel cell stack 115, absorbs the heat generated by the power generation by the cooling medium, and releases the heat absorbed by the cooling medium to the outside of the fuel cell. It is a radiator. The measuring 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 of the fuel cell 115C constituting the fuel cell stack 115 and the characteristics at the time of power generation will be described with reference to FIGS. 2 and 3. 2 and 3 are explanatory views showing the configuration of the fuel cell 115C and the current density at the time of 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 cooling medium inlet 115C6, and a cooling medium outlet 115C7.

The fuel cell stack 115 described above generates electricity in the power generation region 115C1 having the membrane electrode gas diffusion layer junction by the oxygen contained in the air supplied from the air inlet 115C2 and the 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 has not been used for power generation is discharged from the air outlet 115C5 together with the generated water. The heat generated in the power generation region 115C1 during power generation is absorbed by the cooling medium that flows in from the cooling medium inlet 115C6 and flows out from the cooling medium outlet 115C7. The heat absorbed by the cooling medium is released into the atmosphere in the radiator 118.

In FIGS. 2 and 3, the shades attached to the power generation region 115C1 indicate the current density at the time of power generation in each region obtained by dividing the power generation region 115C1 into 8 × 8 regions, and the dark portion indicates the higher current density. The thin part shows the lower current density.

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

During power generation with the maximum current shown in FIG. 2, in the power generation region 115C1, the region with high current density is concentrated on the side close to the air inlet 115C2, and the region with low current density is concentrated on the side close to the air outlet 115C5. There is.

The reason why the current density bias shown in FIG. 2 occurs is as follows. As the overall power generation current increases, the oxygen concentration decreases on the side closer to the air outlet 115C5, which is downstream of the air flow, as compared to the side closer to the air inlet 115C2 to which air is supplied, so that the power generation current increases. descend. Further, as the total power generation current increases, the water generated by the power generation collects on the air outlet 115C5 side, and the water flow rate cannot push out the water, so that the power generation capacity decreases. As a result, the region with high current density is concentrated on the air inlet 115C2 side, and the 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 region 115C1 when power is generated at 50% of the maximum current of the specification, and the current density is not concentrated locally, and the current density is not biased and is uniform over the entire surface. The area exists. That is, in the fuel cell 115C, the power generation region 115C1 is uniformly used. It should be noted that the power generation region 115C1 is in a uniform state over the entire surface without bias in the current density even when power is generated with a current smaller than the maximum current of the specification, which is not limited to 50% of the maximum current of the specification.

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

As described above, in the fuel cell system 100 in which the maximum current of the fuel cell 115C is not used, the aging effect due to the use after shipment cannot be expected, so that it is necessary to uniformly age the entire surface of the power generation region 115C1. In particular, in a fuel cell system used for an industrial vehicle such as a forklift or a stationary fuel cell generator, the maximum power consumption is smaller than that of an automobile, so the maximum current specified by the fuel cell 115C is not used.

[Specific example of aging]
Hereinafter, as the first embodiment, the processing contents for uniformly aging the entire surface of the power generation region 115C1 of the fuel cell 115C will be described below. The aging in the first embodiment is performed by optimizing the water content of the membrane electrode gas diffusion layer conjugate and the electrolyte in the catalyst layer contained in the fuel cell 115C, removing foreign substances on the catalyst surface, reducing the catalyst, and the like. This is intended to improve the initial performance of the stack 115.

(A) Power generation timing and suspension timing:
As shown below, the control unit 101 executes the power generation timing as the first step and the pause timing as the second step. By executing the power generation timing as the first step and the pause timing as the second step in this way, aging can be effectively executed. Here, the power generation timing as the first step and the pause timing as the second step are set as one set, and by repeating this one set a plurality of times, aging can be effectively executed in a short time.

(A1) Power generation timing:
The control unit 101 sets each unit of the fuel cell system 100 so as to provide a constant power generation timing of about 3 minutes during aging. The electric power generated by the fuel cell stack 115 is supplied to the load 300. This fixed time can be set short depending on the rising characteristics of the compressor 113 and the response performance of the hydrogen supply valve 114.

(A2) Pause timing:
The control unit 101 pauses power generation at the pause timing, stops the operation of the DCDC conversion unit 116 with no load, and sets each part of the fuel cell system 100 so that 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 distributed over the entire surface of the fuel cell 115C as much as possible. By doing so, it is possible to effectively optimize the water content as described above and clean the foreign matter adhering to the catalyst. Therefore, a constant pause timing of about 1 minute is provided after the power generation timing.

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

The amount of water generated in one 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 18 [g / mol] is used,
W [g / min] = I [A] / 96485 [C / mol] * Number of layers * 60 [sec] * 18 [g / mol]
As a result, the amount of water W produced can be obtained.
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 specified in the fuel cell 115C. This current is detected by the measuring unit 115s. As a result, at the power generation timing (A1), it is possible to generate water necessary for optimizing the water content of the membrane electrode gas diffusion layer junction and the electrolyte in the catalyst layer, and for cleaning foreign substances adhering to the catalyst.

(C) Hydrogen stoichiometric ratio setting:
In the present embodiment, the hydrogen stoichiometric ratio is the ratio of the amount of hydrogen supplied to the ideal amount of hydrogen required for power generation. Therefore, when the amount of hydrogen supplied is equal to the ideal amount of hydrogen required for power generation, the hydrogen stoichiometric ratio is 1. Further, when the amount of hydrogen at the time of power generation is more than the ideal state, the hydrogen stoichiometric ratio becomes larger than 1.

Hereinafter, the relationship between the hydrogen stoichiometric ratio and the variation in the current density in each region in the fuel cell 115C will be described with reference to FIG. FIG. 4 is a characteristic diagram showing the characteristics of the hydrogen stoichiometric ratio on the anode side and the standard deviation of the 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 of FIG. 4 indicates the variation in the current density at the time of power generation in each region in which the power generation region 115C1 of the fuel cell 115C is divided into 8 × 8 regions.

According to FIG. 4, even when the value of the hydrogen stoichiometric ratio is changed in a range larger than 1, the standard deviation of the current density in each region in the fuel cell 115C hardly changes. Therefore, since the hydrogen stoichiometric ratio is not effective for the variation of the current density, set the hydrogen stoichiometric ratio to a value larger than 1 or prevent the hydrogen stoichiometric ratio to be smaller than 1 at the above power generation timing (A1). 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 so that the pressure on the anode side becomes larger than the pressure on the cathode side in the differential pressure between the electrodes described later, and sets the flow rate of hydrogen.

(D) Air stoichiometric ratio setting:
In this embodiment, the air stoichiometric ratio is the ratio of the amount of air supplied to 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 at the time of power generation is more than the ideal state, the air stoichiometric ratio becomes larger than 1.

Hereinafter, the relationship between the air stoichiometric ratio and the variation in the current density in each region in the fuel cell 115C will be described with reference to FIG. FIG. 5 is a characteristic diagram showing the characteristics of the air stochastic ratio on the cathode side and the standard deviation of the 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 of FIG. 5 indicates the variation in the current density at the time of power generation in each region in which the power generation region 115C1 of the fuel cell 115C is divided 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 in the fuel cell 115C becomes smaller, and the variation in the current density becomes smaller. On the other hand, it is known to utilize the hydrogen adsorption / desorption potential of the catalyst for removing foreign substances on the catalyst surface, which is one of the effects of aging. The hydrogen adsorption / desorption potential will be described with reference to FIG. FIG. 6 is a characteristic diagram showing the cell voltage-current characteristics of the fuel cell 115C during aging in the first embodiment. The hydrogen absorption / desorption potential is in the range where the cell voltage of the fuel cell 115C is about 0.1V to 0.4V. In order to lower the voltage to the region of the hydrogen absorption / desorption potential, it is conceivable to set the air stoichiometric ratio on the cathode side low and generate electricity in the fuel cell 115C in an oxygen-deficient state so that hydrogen remains. This makes it possible to realize reduction of the oxidizing catalyst by hydrogen, which is one of the effects of aging.

However, when the air stoichiometric ratio is set low in this way, the oxygen to be combined with hydrogen decreases in the vicinity of the air outlet 115C5 of the fuel cell 115C, and a power generation defective region having a 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 the range in which the hydrogen adsorption / desorption potential of the catalyst can be used. .. More specifically, the control unit 101 has an air stoichiometric ratio that does not cause an excessive oxygen deficiency in the power generation region 115C1 of the fuel cell 115C, for example, about 1.1 to 1.4, preferably 1.3. Set to degree.

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

(E) Anode inlet pressure setting:
The variation in the current density when the pressure of the hydrogen inlet 115C3 as the anode inlet in the fuel cell 115C is adjusted will be described with reference to FIG. 7. FIG. 7 is a characteristic diagram showing the characteristics of the hydrogen inlet pressure and the standard deviation of the 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 of FIG. 7 indicates the variation in the current density at the time of power generation in each region in which the power generation region 115C1 of the fuel cell 115C is divided into 8 × 8 regions. 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, and the pressure of the hydrogen inlet 115C3 can be, for example, an operating point exceeding 200 kPaA. 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 on the entire surface of the fuel cell 115C to adjust the hydrogen pressure and adjust the pressure on the anode side. Set the differential pressure between the electrodes so that the pressure is higher than the pressure on the cathode side. As a result, the pressure of hydrogen on the anode side increases, so that one of the effects of aging, reduction of the oxidizing catalyst, can be appropriately realized.

(F) Cathode outlet pressure setting:
The variation in the current density when the pressure of the air outlet 115C5 as the cathode outlet in the fuel cell 115C is adjusted will be described with reference to FIG. FIG. 8 is a characteristic diagram showing the characteristics of the air outlet pressure and the standard deviation of the 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 of FIG. 8 indicates the variation in the current density at the time of power generation in each region in which the power generation region 115C1 of the fuel cell 115C is divided into 8 × 8 regions. As described above, as the pressure at the air outlet 115C5 increases, the standard deviation of the current density tends to decrease, and the variation in the current density is suppressed. According to the characteristics of FIG. 7, it is desirable that the pressure of the air outlet 115C5 is as high as possible, but in the aging of the first embodiment, it is desirable to enable reduction of the oxidizing catalyst by hydrogen. Therefore, in the above power generation timing (A1), the control unit 101 controls the compressor 113 on the entire surface of the fuel cell 115C to adjust the amount of air, and the pressure on the cathode side becomes smaller than the pressure on the anode side. Therefore, the differential pressure between the electrodes is set. As a result, the pressure of hydrogen on the anode side increases, so that one of the effects of aging, reduction of the oxidizing catalyst, can be appropriately realized.

(G) Setting of cooling medium temperature:
Generally, the higher the temperature of the cooling medium flowing in the fuel cell stack 115, the higher the activity of the catalyst of the membrane electrode gas diffusion layer junction, and as a result, it is effective for aging. However, if the cooling medium temperature is high, it may induce drying of the membrane electrode gas diffusion layer bonded body. 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 switches on / off the fan of the radiator 118 with reference to the measurement result of the measurement unit 118s, and controls the heat release of the cooling medium so as to satisfy the above set values. By doing so, the water content of the membrane electrode gas diffusion layer junction 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 of activating the fuel cell stack 115 according to the first embodiment is applied will be described with reference to FIG. 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, by assigning the same reference numerals to the same parts as those in FIG. 1, duplicated explanations will be omitted, and only different parts will be described. In the fuel cell system 100 of FIG. 9, the temperatures of the 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 are adjusted. A temperature control unit 119 is provided.

From the viewpoint of humidifying the membrane electrode gas diffusion layer junction 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 condense in the piping. Along with this, in order to prevent dew point temperature hydrogen or air from condensing in the pipe, the control unit 101 controls the temperature control unit 119 so that the temperatures of hydrogen and air are higher than the dew point temperature, for example. Set the above dew point temperature to + 4 ° C. By doing so, it is possible to appropriately humidify the membrane electrode gas diffusion layer bonded body.

[Effects obtained by the embodiment]
By executing each of the above processes (A) to (H) described in the first embodiment, the fuel cell 115C included in the fuel cell stack 115 can be more effectively used in a short time. It is possible to optimize the water content of the electrolyte membrane required for proton conduction in the film electrode gas diffusion layer junction, reduce the oxidizing catalyst, remove foreign substances adhering to the catalyst, and perform aging by cleaning. Further, even if the fuel cell system 100 does not use the maximum current of the fuel cell 115C by executing the aging of the first embodiment before the shipment of the fuel cell system 100, the fuel cell system 100 is shipped at the time of shipment. Since the 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 in which the fuel cell 115C generates power and supplies the generated power to the load 300, and a pause timing in which the fuel cell cell 115C stops power generation, and at the power generation timing. , Set the air stoichiometric ratio on the cathode side to a range where the hydrogen adsorption / desorption potential of the catalyst can be used. As a result, at the power generation timing, it is possible to generate water necessary for optimizing the water content of the membrane electrode gas diffusion layer conjugate and the electrolyte in the catalyst layer, and for cleaning foreign substances adhering to the catalyst. Then, the water generated at the power generation timing can be distributed as much as possible to the entire surface of the fuel cell 115C at the pause timing. By doing so, it is possible to effectively optimize the water content as described above and clean the foreign matter adhering to the catalyst.

(2) The control unit 101 generates power so that the fuel cell 115C 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 substances.

(3) The control unit sets the air strike ratio to 1.1 to 1.4 at the power generation timing. By setting the air stoichiometric ratio low in this way, hydrogen remains even after power generation, and reduction of the oxidizing catalyst by hydrogen can be realized.

(4) The control unit adjusts the amount of air supplied to the fuel cell stack and the amount of hydrogen, and sets the differential pressure between the electrodes so that the pressure on the anode side becomes larger than the pressure on the cathode side. As a result, the pressure of hydrogen on the anode side increases, so that the reduction of the oxidizing catalyst by hydrogen can be appropriately realized.

(5) The control unit 101 is set so that the hydrogen stoichiometric ratio on the anode side does not become smaller than 1 at the power generation timing. By setting the hydrogen stoichiometric ratio in this way, hydrogen that is not used for power generation exists, and reduction of the oxidizing catalyst by hydrogen can be realized.

(6) The control unit 101 controls the heat release of the cooling medium in the radiator 118 so that the temperature of the fuel cell 115C does not exceed the set value. By this control, in the fuel cell 115C, the water content of the membrane electrode gas diffusion layer junction can be optimized while highly activating the catalyst.

(7) The control unit 101 controls the temperature control unit 119 so that the temperature of hydrogen and air passing through the pipe and supplied to the fuel cell stack 115 is higher than the dew point temperature in the fuel cell 115C. By this control, the membrane electrode gas diffusion layer bonded body can be appropriately humidified.

[Other embodiments]
In the above description of the first embodiment, the aging is executed by the control of the control unit 101, but the aging 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 the control unit 101, operate as the control unit that controls the 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 the above (B), the load 300 may be configured by 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 the method for activating the fuel cell stack 115 of the first embodiment described above is executed, it has been described that the fuel cell stack 115 is aged under the control of the control unit 101 in the fuel cell system 100, but the present invention is 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 do not necessarily mean the fuel cell system 100. It does not have to be configured. For example, the fuel cell stack 115 may be aged by a dedicated facility for aging the fuel cell stack 115. Specifically, before assembling the manufactured fuel cell stack 115 to the fuel cell system 100, the fuel cell stack 115 is aged by using a dedicated facility having a control unit capable of performing aging and a load. Then, the fuel cell stack 115 aged using the dedicated equipment as a front-end process is assembled to the fuel cell system 100 as a back-end process.

100 Fuel Cell System, 101 Control Unit, 112 Hydrogen Tank, 113 Compressor, 114 Hydrogen Supply Valve, 115 Fuel Cell Stack, 115s Measuring Unit, 115C Fuel Cell Cell, 115C1 Power Generation Area, 115C2 Air Inlet, 115C3 Hydrogen Inlet, 115C4 Hydrogen Outlet , 115C5 air outlet, 115C6 cooling medium inlet, 115C7 cooling medium outlet, 116 DCDC converter, 117 power storage device, 118 radiator, 118s measuring unit, 119 temperature control unit.

Claims (7)

It is provided with a fuel cell stack in which fuel cell 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
The first step of generating electricity in the fuel cell and supplying the generated electricity to the load,
The second step of suspending the power generation of the fuel cell and
And run
A method for activating a fuel cell stack in which the air stoichiometric ratio on the cathode side in the first step is set within a range in which the hydrogen adsorption / desorption potential of the catalyst can be used. The method for activating a fuel cell stack according to claim 1, wherein the control unit generates electricity so that the fuel cell cells generate a maximum current in the first step. The method for activating a fuel cell stack according to claim 1 or 2, wherein the control unit sets the air stoichiometric ratio to 1.1 to 1.4 in the first step. From claim 1, the control unit adjusts the amount of the air supplied to the fuel cell stack and the amount of the hydrogen, and sets the differential pressure between the electrodes so that the pressure on the anode side becomes larger than the pressure on the cathode side. The method for activating a fuel cell stack according to any one of claims 3. The method for activating a fuel cell stack according to claim 4, wherein the control unit is set so that the hydrogen stoichiometric ratio on the anode side does not become smaller than 1 in the first step. It is provided with a radiator that absorbs the heat generated in the fuel cell by a cooling medium and releases the absorbed heat to the outside of the fuel cell.
The activity of the fuel cell stack according to any one of claims 1 to 5, wherein the control unit controls the release of the heat in the radiator so that the temperature of the fuel cell does not exceed the set value. How to make it. Further provided with a temperature control unit for adjusting the temperature of the hydrogen and the air,
The control unit controls the temperature control unit so that the temperature of the hydrogen and the air that pass through the pipe and is supplied to the fuel cell stack is higher than the dew point temperature in the fuel cell. The method for activating the fuel cell stack according to any one of claims 6.

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