Air-cooled fuel cell system

Abstract

Provided is a fuel cell system capable of appropriately recovering the activity of a cathode catalyst. The fuel cell system is an air-cooled fuel cell system, and is characterized in that: the fuel cell system is provided with a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell; the fuel cell has a reaction air path and a cooling air path having flow path structures in which the reaction air and the cooling air are independent from each other, and when the activity of a cathode catalyst of the fuel cell is reduced and there is a need to perform a recovery control for improving the activity, the reaction air path and the cooling air path are used as the recovery control. The fuel cell system reduces the supply amount of the reaction air to the fuel cell while maintaining the supply of the hydrogen to the fuel cell and the supply of the cooling air to the fuel cell.

Description

Technical Field

[0001] The present disclosure relates to an air-cooled fuel cell system. Background Art

[0002] Various technologies have been proposed regarding fuel cells (FC) such as those disclosed in Patent Documents 1 to 5.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2005-216783

[0004] Patent Document 2: Japanese Patent Application Publication No. 2017-510954

[0005] Patent Document 3: Japanese Patent Application Publication No. 2022-185251

[0006] Patent Document 4: Japanese Patent Application Publication No. 2022-185247

[0007] Patent Document 5: Japanese Patent Application Publication No. 2008-192468

[0008] In conventional open air-cooled fuel cells, it is not possible to simultaneously restrict the inflow of cooling air and reaction air. Therefore, when the activity of the cathode catalyst of the fuel cell decreases, it is not possible to perform recovery control to increase the activity. Summary of the invention

[0009] The present disclosure has been made in view of the above-mentioned actual situation, and a main object thereof is to provide an air-cooled fuel cell system capable of appropriately recovering the activity of a cathode catalyst.

[0010] In the first embodiment of the present disclosure, a fuel cell system is provided, which is an air-cooled fuel cell system, characterized in that the fuel cell system comprises a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell, the fuel cell having a reaction air flow path and a cooling air flow path with independent flow path structures for the reaction air and the cooling air, and when the activity of the cathode catalyst of the fuel cell decreases and recovery control for increasing the activity is required, the fuel cell system maintains the supply of the hydrogen and the cooling air to the fuel cell as the recovery control, and reduces the supply of the reaction air to the fuel cell.

[0011] In the second embodiment of the present disclosure, it can also be constructed as follows: on the basis of the first embodiment, the reaction air system has a reaction air supply mechanism, the cooling air system has a cooling air supply mechanism, the hydrogen exhaust flow path of the hydrogen system merges with the cooling air exhaust flow path of the cooling air system, and during the recovery control, the fuel cell system stops the reaction air supply mechanism and drives the cooling air supply mechanism to dilute the hydrogen with the cooling air and discharge it to the outside of the fuel cell system.

[0012] In the third embodiment of the present disclosure, it can also be constructed as follows: on the basis of the first embodiment, after the above-mentioned recovery control starts, when at least one of the conditions that the voltage of the above-mentioned fuel cell is reduced to a specified voltage and a specified time has passed is met, the above-mentioned fuel cell system increases the supply amount of the above-mentioned reaction air to the above-mentioned fuel cell.

[0013] In the fourth embodiment of the present disclosure, it can also be constructed as follows: on the basis of the first embodiment, the above-mentioned fuel cell system has an electrical system, the above-mentioned electrical system has a diode on the power line with the above-mentioned fuel cell, and the above-mentioned fuel cell system connects the above-mentioned fuel cell to the above-mentioned power line during the above-mentioned recovery control.

[0014] In the fifth embodiment of the present disclosure, it can also be configured as follows: based on the first embodiment, the above-mentioned fuel cell system has an electrical system, the above-mentioned electrical system has a fuel cell relay on the power line with the above-mentioned fuel cell, and the above-mentioned fuel cell system disconnects the above-mentioned fuel cell relay during the above-mentioned recovery control.

[0015] The fuel cell system of the present disclosure can appropriately recover the activity of the cathode catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an exploded perspective schematic diagram showing an example of a single cell of a fuel cell included in the fuel cell system of the present disclosure.

[0017] Figure 2 It is a perspective schematic diagram showing an example of a fuel cell stack included in the fuel cell system of the present disclosure.

[0018] Figure 3 1 is a system configuration diagram showing an example of the fuel cell system of the present disclosure.

[0019] Figure 4 1 is a circuit diagram showing an example of an electrical system included in the fuel cell system of the present disclosure.

[0020] Figure 5 1 is a flowchart showing an example of control of the fuel cell system of the present disclosure.

[0021] Figure 6 : is a flowchart showing another example of control of the fuel cell system of the present disclosure.

[0022] Description of Reference Numerals

[0023] 1…battery cell; 2…cooling fin (cooling air flow path); 3…reaction air inlet; 4…reaction air outlet; 5…hydrogen inlet; 6…hydrogen outlet; 7…cooling air (cooling gas); 8…hydrogen; 9…reaction air; 10…fuel cell stack; 11…diaphragm; 12…MEA, resin frame; 20…reaction air system; 21…reaction air intake port; 22…air blower; 23…inlet side sealing valve; 24…outlet side sealing valve; 30…cooling air system; 31…cooling fan; 40…hydrogen system; 41…hydrogen tank; 42…hydrogen inlet valve; 43…gas-liquid separator; 44…hydrogen purge valve; 45…hydrogen pump; 50…electrical system; 51…power line; 52…diode; 53…relay; 54…power consumption absorption mechanism; 55…auxiliary equipment; 56…power consumption equipment. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present disclosure. In addition, matters required for the implementation of the present disclosure other than matters specifically mentioned in this specification (for example, the general structure and manufacturing process of the fuel cell system that does not characterize the present disclosure) can be understood as design matters for those skilled in the art based on the prior art in the art. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in the art.

[0025] In addition, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships.

[0026] In the present disclosure, the gas supplied to the anode of the fuel cell is the fuel gas (anode gas), and the gas supplied to the cathode of the fuel cell is the oxidant gas (cathode gas). The fuel gas is a gas mainly containing hydrogen, and may also be hydrogen. The oxidant gas is a gas containing oxygen, and may also be oxygen, air, etc. In the present disclosure, the air serving as the oxidant gas is referred to as reaction air, and the air serving as the cooling gas is referred to as cooling air.

[0027] In the present disclosure, a fuel cell system is provided, which is an air-cooled fuel cell system, characterized in that the fuel cell system includes a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell, the fuel cell having a reaction air flow path and a cooling air flow path with independent flow path structures for the reaction air and the cooling air, and when the activity of the cathode catalyst of the fuel cell decreases and recovery control for increasing the activity is required, as the recovery control, the fuel cell system maintains the supply of the hydrogen to the fuel cell and the supply of the cooling air to the fuel cell, and reduces the supply of the reaction air to the fuel cell.

[0028] The present disclosure relates to improving the performance of an air-cooled fuel cell. In a system having independent flow paths for reaction air and cooling air, the reaction air system is controlled to reduce the voltage, thereby achieving a cathode catalyst recovery effect.

[0029] In an air-cooled fuel cell, the volume of the fluid used for cooling is larger than that of a water-cooled fuel cell, and the flow path structure for flowing the fluid is also larger.

[0030] For example, the cooling water required for 4 kW of cooling is about 5 L / min, while in the case of air, more than 10,000 L / min is required.

[0031] If the fuel cell continues to generate electricity, the accumulation of oxides on the catalyst surface of the cathode will reduce the catalyst activity and the power generation efficiency. At this time, the power generation efficiency can be restored by performing a recovery process. For the recovery process, it is necessary to make the cathode oxygen-deficient to reduce the cell potential. In addition, since the power supply during the recovery is reduced, it is necessary to perform the process as quickly as possible.

[0032] In an open air-cooled fuel cell, since the reaction air system cannot be sealed, it takes a long time to reduce the potential if the potential cannot be reduced in a non-power-generating state or if the enclosed space is large. In addition, when reducing the potential while generating power, complex control such as balancing the current and air flow is required.

[0033] In an open air-cooled fuel cell, since there is only one system of air supply mechanism, the air supply mechanism cannot be stopped due to the dilution of exhaust hydrogen. In order to reduce the potential, complex control is required while generating electricity, or ancillary devices such as bypass valves need to be installed.

[0034] Therefore, in an open air-cooled fuel cell, it is difficult to seal the air system due to its structure. Even if it can be sealed, the sealed volume is quite large, making it difficult to reduce the potential in a short time for recovery processing.

[0035] The fuel cell system includes a fuel cell that generates electricity by reacting hydrogen with air, a hydrogen system that supplies hydrogen required for power generation to the fuel cell, a reaction air system that supplies reaction air to the fuel cell, and a cooling air system that supplies cooling air to the fuel cell to cool the heat generated by power generation.

[0036] The fuel cell may be a single cell (battery cell) having only one fuel cell, or may be a fuel cell stack (battery stack) which is a stacked body in which a plurality of cells are stacked.

[0037] In the present disclosure, there are cases where both a battery cell and a fuel cell stack are referred to as a fuel cell.

[0038] The number of stacked cells in the fuel cell stack is not particularly limited, and may be, for example, 2 to several hundred.

[0039] The fuel cell stack may include corrugated cooling fins serving as cooling air flow paths in each cell.

[0040] The fuel cell stack may have a current collecting plate, a pressure plate, etc. at the end portions in the stacking direction.

[0041] The fuel cell has a reaction air flow path (oxidant gas flow path) and a cooling air flow path (cooling gas flow path) with independent flow paths for reaction air and cooling air, and may further have a hydrogen flow path (fuel gas flow path).

[0042] The independent flow path structure of reaction air and cooling air means that the air does not communicate between the flow paths from the supply of air to the fuel cell to the exhaust of air from the fuel cell. In addition, the flow paths for exhausting the air exhausted from the fuel cell to the outside of the fuel cell system may be independent or not.

[0043] The cell may also include a flow path structure that allows the reaction air and the cooling air to flow so that the flow of the cooling air intersects with the flow of the reaction air in a plan view. The flow of the cooling air and the flow of the reaction air may intersect or be orthogonal.

[0044] The battery cell may have a power generation unit.

[0045] The shape of the power generation unit may be a rectangle in a plan view.

[0046] The power generation unit may be a membrane electrode assembly (MEA) including an electrolyte membrane and two electrodes.

[0047] The electrolyte membrane may also be a solid polymer electrolyte membrane. As the solid polymer electrolyte membrane, for example, a fluorine electrolyte membrane such as a film of perfluorosulfonic acid containing water, and a hydrocarbon electrolyte membrane may be cited. As the electrolyte membrane, for example, a Nafion membrane (manufactured by DuPont) may also be used.

[0048] The two electrodes are the anode (fuel or hydrogen) and the cathode (oxygen or air).

[0049] The electrode includes a catalyst layer and may include a gas diffusion layer as required, and the power generation unit may be a membrane electrode gas diffusion layer assembly (MEGA).

[0050] The catalyst layer may include a catalyst including a catalyst metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity.

[0051] As the catalyst metal, for example, platinum (Pt) and alloys composed of Pt and other metals (for example, Pt alloys mixed with cobalt, nickel, etc.) can be used. The catalyst metal used as the cathode catalyst and the catalyst metal used as the anode catalyst may be the same or different.

[0052] The electrolyte may be a fluorine-based resin or the like. For example, a Nafion solution or the like may be used as the fluorine-based resin.

[0053] The above-mentioned catalyst metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalyst metal (catalyst-supporting carrier) and the electrolyte may be present in a mixed state.

[0054] Examples of the carrier for supporting the catalyst metal include carbon materials such as carbon generally available on the market.

[0055] The gas diffusion layer may be a conductive member having pores or the like.

[0056] Examples of the conductive member include carbon porous bodies such as carbon cloth and carbon paper, and metal porous members such as metal mesh and foamed metal.

[0057] The cells of the fuel cell may also include a membrane.

[0058] The diaphragm collects the current generated by power generation and functions as a partition. In the battery cell of a fuel cell, the diaphragm is usually arranged on both sides of the stacking direction of the power generation part in a way that a pair of diaphragms sandwich the power generation part. One side of the pair of diaphragms is the anode diaphragm, and the other side is the cathode diaphragm.

[0059] The anode separator may have grooves serving as hydrogen flow paths on the surface on the power generation portion side, and may have grooves serving as cooling air flow paths on the surface on the opposite side to the power generation portion.

[0060] The cathode separator may have grooves serving as reaction air flow paths on the surface facing the power generation portion, and may have grooves serving as cooling air flow paths on the surface facing the opposite side to the power generation portion.

[0061] The separator may have holes constituting manifolds such as supply holes and discharge holes for allowing the fluid to flow in the stacking direction of the battery cells.

[0062] The separator may be, for example, dense carbon obtained by compressing carbon to be airtight, or press-formed metal (for example, iron, titanium, stainless steel, etc.).

[0063] The battery cell may also be provided with an insulating resin frame disposed on the outside (periphery) of the surface direction of the membrane electrode assembly between the anode separator and the cathode separator. The resin frame is formed into a plate-like and frame-like shape using a thermoplastic resin, and the anode separator and the cathode separator are sealed while the membrane electrode assembly is maintained in its central area. As the resin frame, for example, resins such as PE, PP, PET, and PEN can be used. The resin frame may also be a three-layer sheet body consisting of three layers in which an adhesive layer is disposed on the surface layer.

[0064] The fuel cell system may also include a control device, which controls the reaction air system, the hydrogen system, the cooling air system, etc., and may also control the entire fuel cell system.

[0065] The control device physically has, for example, a processing unit such as a CPU (central processing unit), a ROM (read-only memory) for storing control programs and control data processed by the CPU, a storage device such as a RAM (random access memory) mainly used as various work areas for control processing, and an input / output interface. It can also be an ECU (electronic control unit), etc.

[0066] The reaction air system supplies reaction air as oxidant gas to the fuel cell and adjusts the flow rate of the reaction air. The reaction air system may also include reaction air piping and the like.

[0067] The hydrogen system supplies hydrogen as fuel gas to the fuel cell and adjusts the flow rate of the hydrogen. The hydrogen system may also include a hydrogen tank, a hydrogen inlet valve, an ejector, a gas-liquid separator, a hydrogen purge valve, an ejector for hydrogen circulation, a hydrogen pump for hydrogen circulation, and hydrogen piping.

[0068] The cooling air system supplies cooling air as cooling gas to the fuel cell and adjusts the flow rate of the cooling air.

[0069] The reaction air system may be configured such that the reaction air system includes an inlet-side sealing valve at an inlet of the reaction air of the fuel cell and an outlet-side sealing valve at an outlet of the reaction air of the fuel cell.

[0070] In the present disclosure, a fuel cell has a flow path structure in which reaction air and cooling air are independent, and in a reaction air system, valves (inlet side sealing valve and outlet side sealing valve) are provided at the inlet and outlet of the reaction air of the fuel cell, whereby the fuel cell can seal the cathode of the fuel cell with a smaller volume than the case of having a flow path structure in which the reaction air and cooling air are shared. During the power generation of the fuel cell, and when the activity of the cathode catalyst of the fuel cell decreases and recovery control is required to increase the activity, the valves at the inlet and outlet of the reaction air are sealed so that the sealed small amount of oxygen is quickly consumed, thereby reducing the potential of the fuel cell in a short time.

[0071] At this time, since the hydrogen in the anode is consumed, hydrogen supply is continued in order to suppress catalyst degradation associated with the generation of abnormal potential due to hydrogen deficiency.

[0072] When the activity of the cathode catalyst of the fuel cell decreases and recovery control to increase the activity is required, the fuel cell system maintains the supply of hydrogen and the supply of cooling air to the fuel cell as the recovery control, and reduces the supply of reaction air to the fuel cell.

[0073] During the recovery control (recovery process), the supply of hydrogen to the fuel cell is maintained in order to prevent abnormal potential. During the recovery control (recovery process), at least the supply of reaction air to the fuel cell is reduced, and the supply of reaction air to the fuel cell is stopped as needed, and the inlet and outlet valves (inlet side sealing valve and outlet side sealing valve) of the reaction air system are closed to seal the cathode of the fuel cell. Moreover, the fuel cell is reduced to a specified voltage. If the fuel cell reaches the specified voltage, the inlet and outlet valves (inlet side sealing valve and outlet side sealing valve) of the reaction air system are opened.

[0074] It can also be determined that recovery control is required when at least one of the following conditions is met. The above conditions are when the voltage of the fuel cell deviates from the assumed voltage. When continuous power generation operation is performed for more than a certain period of time, or when the fuel cell is placed in a non-power generation state for more than a certain period of time. That is, when at least one of these conditions is met, it can also be considered that the activity of the cathode catalyst is reduced.

[0075] In the present disclosure, after the start of the recovery control, when at least one of the voltage of the fuel cell drops to a predetermined voltage and a predetermined time has passed, the fuel cell system may increase the amount of the reaction air supplied to the fuel cell.

[0076] Whether the recovery control is terminated is determined based on any one or a combination of the following. Voltage sensors may be provided at both ends of the fuel cell stack to detect the total voltage, and the recovery control is determined to be terminated when the total voltage value drops to a specified voltage. Voltage sensors may be provided at all or part of the cells, and the recovery control is determined to be terminated when the voltage value of at least one of the cells drops to a specified voltage. The time until the voltage drops to a specified voltage may also be recorded in advance, and the recovery control is determined to be terminated when the specified time has passed.

[0077] The reaction air system may include a reaction air supply mechanism, the cooling air system may include a cooling air supply mechanism, and the hydrogen exhaust flow path of the hydrogen system may merge with the cooling air exhaust flow path of the cooling air system.

[0078] Furthermore, the hydrogen exhaust flow path of the hydrogen system may further include a merging portion capable of merging with the reaction air exhaust flow path of the reaction air system.

[0079] The reaction air system and the cooling air system have independent air supply mechanisms, and the hydrogen exhaust flow path merges with the cooling air exhaust flow path. Therefore, when the control is restored, the fuel cell system stops the reaction air supply mechanism and drives the cooling air supply mechanism, thereby being able to dilute the hydrogen with cooling air and discharge it to the outside of the fuel cell system, and temperature control can be performed.

[0080] The reaction air supply mechanism and the cooling air supply mechanism may also be an air compressor, an air pump, an air blower, an air fan, etc. respectively.

[0081] The reaction air system may include a reaction air intake port for taking in reaction air from outside the fuel cell system, and a pressure loss body such as an air filter may be provided at the reaction air intake port.

[0082] The cooling air system may include a cooling air intake port for taking in cooling air from outside the fuel cell system, and a pressure loss body such as an air filter may be provided at the cooling air intake port.

[0083] The fuel cell system may also include an electrical system.

[0084] The electrical system may or may not include a diode on the power line to the fuel cell and a relay for the fuel cell. By including a diode, the generation of reverse current from the power line side to the fuel cell can be avoided.

[0085] The fuel cell system may also connect the fuel cell to the power line when resuming control.

[0086] By performing recovery control while the fuel cell is connected to the power line, oxygen consumption of the reaction air system is completed earlier, and the recovery control time is shortened. In addition, if the connection between the fuel cell and the power line is cut off during recovery control to make the fuel cell open circuit, when oxygen is present at the cathode and hydrogen is present at the anode, the cell voltage rises to a high potential (near 1.0V) and oxidation of the catalyst is aggravated, thereby aggravating the performance degradation of the catalyst layer. However, by performing recovery control while the fuel cell is connected to the power line, the voltage of the fuel cell is suppressed to the fuel cell voltage V1 ≤ the power line voltage V2, thereby preventing the cell from reaching a high potential during recovery control.

[0087] The electrical system may include a fuel cell relay on the power line to the fuel cell, and may or may not include a diode.

[0088] When the electrical system has a fuel cell relay on the power line and does not have a diode, the fuel cell system may turn off the fuel cell relay when performing recovery control.

[0089] When a diode is not provided on the power line of the electrical system due to the cost and size of the fuel cell system, the cell temporarily reaches a high potential, but in order to prevent reverse current from the power line, recovery control may be performed after the relay is disconnected.

[0090] Figure 1 It is an exploded perspective schematic diagram showing an example of a single cell of a fuel cell included in the fuel cell system of the present disclosure.

[0091] Figure 1 The cell 1 shown in the figure has cooling fins (cooling air flow path) 2 which serve as a flow path for cooling air (cooling gas) 7, a reaction air inlet 3, a reaction air outlet 4, a hydrogen inlet 5, a hydrogen outlet 6, two diaphragms 11, and an MEA and a resin frame 12 sandwiched between the two diaphragms 11. Figure 1 As shown, the cell 1 of the fuel cell has a flow path structure in which the reaction air 9 and the cooling air 7 are independent.

[0092] Figure 2 It is a perspective schematic diagram showing an example of a fuel cell stack included in the fuel cell system of the present disclosure.

[0093] Figure 2 The fuel cell stack 10 shown is a stacked body in which a plurality of battery cells 1 are stacked.

[0094] Figure 3 1 is a system configuration diagram showing an example of the fuel cell system of the present disclosure.

[0095] Figure 3The fuel cell system shown in the figure includes a fuel cell stack 10, a reaction air system 20, a cooling air system 30, and a hydrogen system 40. The reaction air system 20 includes a reaction air intake port 21, an air blower 22, an inlet side sealing valve 23, and an outlet side sealing valve 24. The cooling air system 30 includes a cooling fan 31. The hydrogen system 40 includes a hydrogen tank 41, a hydrogen inlet valve 42, a gas-liquid separator 43, a hydrogen purge valve 44, and a hydrogen pump 45. Figure 3 The fuel cell system shown in the figure is provided with sealing valves 23 and 24 at the inlet and outlet of the reaction air system 20 , and is provided with independent air supply mechanisms 22 and 31 in the reaction air system 20 and the cooling air system 30 .

[0096] Figure 4 1 is a circuit diagram showing an example of an electrical system included in the fuel cell system of the present disclosure.

[0097] Figure 4 The illustrated electrical system 50 includes a power line 51 , a diode 52 , a relay 53 , a power consumption absorbing mechanism 54 such as a battery or a capacitor, auxiliary equipment 55 , and power consuming equipment 56 .

[0098] By providing the diode 52 on the power line 51 , the fuel cell stack 10 is connected to the power line 51 during the recovery control, thereby avoiding the generation of reverse current from the power line 51 to the fuel cell stack 10 and shortening the recovery control time.

[0099] Figure 5 1 is a flowchart showing an example of control of the fuel cell system of the present disclosure.

[0100] First, the fuel cell system determines whether recovery control is required (S101). If recovery control is required, the fuel cell system closes the inlet and outlet valves of the reaction air system (S102) to start recovery control. Furthermore, the fuel cell system determines whether the voltage of the fuel cell drops to a predetermined determination threshold (S103).

[0101] When it is determined that the voltage of the fuel cell has dropped to a predetermined determination threshold, the fuel cell system opens the inlet and outlet valves of the reaction air system to terminate the recovery control ( S104 ).

[0102] Figure 6 : is a flowchart showing another example of control of the fuel cell system of the present disclosure.

[0103] First, the fuel cell system determines whether recovery control is required (S201). If it is determined that recovery control is required, the fuel cell system closes the inlet and outlet valves of the reaction air system to start recovery control (S202). Furthermore, the fuel cell system determines whether the implementation time of the recovery control has passed a prescribed time (S203). If it is determined that the implementation time of the recovery control has passed a prescribed time, the fuel cell system opens the inlet and outlet valves of the reaction air system to end recovery control (S204).

Claims

1. A fuel cell system, which is an air-cooled fuel cell system, characterized in that: The fuel cell system includes a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell. The fuel cell has a reaction air flow path and a cooling air flow path in a structure in which the reaction air and the cooling air have independent flow paths. When the activity of the cathode catalyst of the fuel cell decreases and recovery control to increase the activity is required, as the recovery control, the fuel cell system maintains the supply of hydrogen to the fuel cell and the supply of cooling air to the fuel cell, and reduces the supply of reaction air to the fuel cell.

2. The fuel cell system according to claim 1, characterized in that: The reaction air system has a reaction air supply mechanism. The cooling air system comprises a cooling air supply mechanism. The hydrogen exhaust flow path of the hydrogen system merges with the cooling air exhaust flow path of the cooling air system, During the recovery control, the fuel cell system stops the reaction air supply mechanism and drives the cooling air supply mechanism to dilute the hydrogen with the cooling air and discharge it to the outside of the fuel cell system.

3. The fuel cell system according to claim 1, characterized in that: After the recovery control is started, when at least one of the conditions that the voltage of the fuel cell decreases to a predetermined voltage and a predetermined time has elapsed is satisfied, the fuel cell system increases the amount of the reactant air supplied to the fuel cell.

4. The fuel cell system according to claim 1, characterized in that: The fuel cell system comprises an electrical system, The electrical system has a diode on a power line to the fuel cell, The fuel cell system connects the fuel cell to the power line during the recovery control.

5. The fuel cell system according to claim 1, characterized in that: The fuel cell system comprises an electrical system, The electrical system includes a fuel cell relay on a power line to the fuel cell. The fuel cell system turns off the fuel cell relay during the recovery control.

6. The fuel cell system according to claim 1, characterized in that: The fuel cell has at least one single cell, which has an anode diaphragm, a power generation unit, and a cathode diaphragm in sequence. The cathode diaphragm has the reaction air flow path on one side of the power generation unit and the cooling air flow path on the opposite side of the power generation unit.

7. The fuel cell system according to claim 6, characterized in that: The single cell has corrugated cooling fins as the cooling air flow path.

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