Fuel cell activation method and fuel cell system

Abstract

The invention relates to an activation method of a fuel cell and a fuel cell system. The fuel cell comprises an anode and a cathode which are oppositely arranged, and an anode catalyst layer arranged on one side, close to the cathode, of the anode. The activation method of the fuel cell comprises the following steps: receiving a shutdown instruction; the fuel cell system is shut down in response to the shutdown instruction, and oxygen-containing gas is left on one side of the anode; and restarting the fuel cell system, and introducing hydrogen-containing gas into the anode side, so that the hydrogen-containing gas reacts with the oxygen-containing gas remained on the anode side to generate instantaneous current, thereby stripping residues on the surface of the anode catalyst layer, and activating the fuel cell. The activation method of the fuel cell is beneficial to improving the activation efficiency of the fuel cell and can also realize online activation.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a fuel cell activation method and a fuel cell system. Background Art

[0002] A fuel cell is a power generation device that directly converts the chemical energy of a fuel into electrical energy. It has the advantages of high power density, no pollution, and low noise, and has broad application prospects. The core component of a proton exchange membrane fuel cell is a membrane electrode, which includes a cathode catalyst layer, a proton exchange membrane, and an anode catalyst layer stacked in sequence. The cathode is located on the side of the cathode catalyst away from the proton exchange membrane, and the anode is located on the side of the anode catalyst away from the proton exchange membrane.

[0003] As the fuel cell system runs longer, the performance of the fuel cell will gradually decline. The performance decay of the fuel cell includes irreversible decay and reversible decay, among which reversible decay can restore the performance of the fuel cell through activation. One of the reasons for reversible decay is that the reaction is not sufficient, resulting in residues such as sulfides and nitrides in the catalyst layer. The residues cover the surface of the catalyst layer, reducing the active sites of the catalyst layer, which reduces the reaction degree of the fuel cell, thereby causing the performance of the fuel cell to decline.

[0004] However, the traditional activation method is to apply a short high current to the fuel cell after the fuel cell system is shut down to remove the residue on the surface of the catalyst layer, which requires an external power supply outside the fuel cell stack. In order to connect the external power supply outside the fuel cell stack, some parts of the fuel cell system need to be removed, which makes the operation of the traditional activation method complicated. Summary of the invention

[0005] In order to simplify the activation method of a fuel cell, the present application provides an activation method of a fuel cell and a fuel cell system.

[0006] The embodiment of the present application provides a method for activating a fuel cell, wherein the fuel cell comprises an anode and a cathode arranged relatively to each other, and an anode catalyst layer arranged on the side of the anode close to the cathode. The method for activating a fuel cell comprises: receiving a shutdown command; shutting down the fuel cell system in response to the shutdown command, and leaving oxygen-containing gas on the anode side; restarting the fuel cell system, passing hydrogen-containing gas to the anode side, so that the hydrogen-containing gas and the oxygen-containing gas remaining on the anode side react to generate instantaneous current, so as to strip off the residue on the surface of the anode catalyst layer, and activate the fuel cell.

[0007] In the above-mentioned method for activating a fuel cell, after the fuel cell system is shut down in response to a shutdown command, oxygen-containing gas remains on the anode side, so that when the fuel cell system is restarted and hydrogen-containing gas is introduced into the anode side, the hydrogen-containing gas reacts with the oxygen-containing gas remaining on the anode side to generate a transient current, thereby stripping the residue on the surface of the anode catalyst layer, restoring the active sites of the anode catalyst layer, and thus improving the performance of the fuel cell, and realizing the activation of the fuel cell. The above-mentioned method for activating a fuel cell can generate a transient current in the fuel cell for removing the residue on the surface of the anode catalyst layer, without the need for an external power supply outside the fuel cell, and correspondingly without the need to remove components in the fuel cell system, which simplifies the activation method of the fuel cell, is conducive to improving the activation efficiency of the fuel cell, and can also realize online activation.

[0008] In some of the embodiments, the fuel cell activation method further includes: after receiving a shutdown command and before shutting down the fuel cell system in response to the shutdown command, selecting to enter a fuel cell activation mode or a normal shutdown purge mode; wherein, oxygen-containing gas is allowed to remain on the anode side, and the fuel cell system is restarted, hydrogen-containing gas is introduced to the anode side, and the hydrogen-containing gas and the residual oxygen-containing gas on the anode side react to generate an instantaneous current to strip off the residues on the surface of the anode catalyst layer, thereby activating the fuel cell, all of which are performed in the fuel cell activation mode.

[0009] In some embodiments, the fuel cell further includes a proton exchange membrane between the anode catalyst layer and the cathode; the fuel cell system is shut down in response to a shutdown command, and oxygen-containing gas is left on the anode side, including: in the process of shutting down the fuel cell system in response to the shutdown command, oxygen-containing gas is continuously provided to the cathode side; after receiving the shutdown command until the voltage of the fuel cell drops to a first threshold, hydrogen-containing gas is continuously provided to the anode side; after the voltage of the fuel cell drops to the first threshold, the oxygen-containing gas on the cathode side permeates to the anode side through the proton exchange membrane, and residual oxygen-containing gas is formed on the anode side. By continuously providing oxygen-containing gas to the cathode side and providing hydrogen-containing gas to the anode side, the water content inside the fuel cell can be effectively reduced, and residual oxygen-containing gas is formed on the anode side without changing the ventilation type on the anode side, and the operation is simple.

[0010] In some embodiments, the method for activating a fuel cell further includes: shutting down the fuel cell system after the voltage of the fuel cell decreases to a second threshold; wherein the second threshold is smaller than the first threshold.

[0011] In some embodiments, the method for activating a fuel cell further includes: after the voltage of the fuel cell drops to a first threshold, connecting the fuel cell to a pressure relief element to drop the voltage of the fuel cell to a second threshold. The pressure relief element can quickly consume the voltage of the fuel cell, causing the voltage of the fuel cell to drop to the second threshold quickly, thereby improving the efficiency of shutting down the fuel cell system.

[0012] In some of the embodiments, the oxygen-containing gas includes air; the fuel cell is also connected to a drain valve and a nitrogen exhaust valve; the activation method of the fuel cell also includes: after receiving a shutdown command and until the voltage of the fuel cell drops to a second threshold, periodically opening the drain valve and the nitrogen exhaust valve to discharge nitrogen and water.

[0013] In some of the embodiments, the method for activating a fuel cell further includes: in the process of shutting down the fuel cell system in response to a shutdown instruction, cooling the fuel cell so that the temperature of the fuel cell reaches room temperature.

[0014] In some of the embodiments, in the process of shutting down the fuel cell system in response to the shutdown instruction, the gas pressure range of the oxygen-containing gas provided to the cathode side is 110kPa~130kPa; the gas pressure range of the hydrogen-containing gas provided to the anode side is 120kPa~140kPa.

[0015] In the second aspect, the embodiment of the present application provides a fuel cell system, including: a fuel cell, a gas supply device and a control device. The fuel cell includes an anode and a cathode arranged relatively to each other, and an anode catalyst layer arranged on the side of the anode close to the cathode; the gas supply device is configured to: provide hydrogen-containing gas to the anode side and oxygen-containing gas to the cathode side; the control device is connected to the gas supply device and is configured to: in response to a shutdown command to shut down the fuel cell system, send a first control command to the gas supply device so that oxygen-containing gas remains on the anode side after the fuel cell system is shut down; and, in response to a restart command, send a second control command to the gas supply device so that hydrogen-containing gas is passed into the anode side, so that the hydrogen-containing gas and the oxygen-containing gas remaining on the anode side react to generate instantaneous current, and strip the residue on the surface of the anode catalyst layer to activate the fuel cell.

[0016] In the above-mentioned fuel cell system, in response to the shutdown command, when shutting down the fuel cell system, the control device sends a first control command to the gas supply device, so that oxygen-containing gas remains on the anode side after shutting down the fuel cell system; in response to the restart command, the control device sends a second control command to the gas supply device, so that hydrogen-containing gas is passed into the anode side, and the hydrogen-containing gas reacts with the oxygen-containing gas remaining on the anode side to generate instantaneous current, thereby stripping the residue on the surface of the anode catalyst layer, restoring the active sites of the anode catalyst layer, and thus improving the performance of the fuel cell, and realizing the activation of the fuel cell. That is, the above-mentioned fuel cell system can realize the activation of the fuel cell without an external power supply.

[0017] In some of the embodiments, the fuel cell system also includes a selection device, which is connected to the control device, and the selection device is configured to: send a selection instruction to enter a fuel cell activation mode or a normal shutdown purge mode to the control device after the control device receives a shutdown instruction and before shutting down the fuel cell system in response to the shutdown instruction, wherein the first control instruction and the second control instruction are generated in the fuel cell activation mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A flowchart of a fuel cell activation method provided by an embodiment;

[0020] Figure 2 A flow chart of another method for activating a fuel cell provided by an embodiment;

[0021] Figure 3 A structural block diagram of a fuel cell system provided by an embodiment;

[0022] Figure 4 for Figure 3 A schematic diagram of the structure of the fuel cell system;

[0023] Figure 5 for Figure 4 A flow chart of a method for activating a fuel cell system;

[0024] Description of reference numerals:

[0025] 1- fuel cell; 11- fuel cell stack; 2- gas supply device; 21- hydrogen source; 22- pressure regulating valve; 23- gas compression device; 24- gas cooling device; 25- humidification device; 26- back pressure valve; 27- front stop valve; 28- rear stop valve; 29- bypass valve; 3- control device; 4- circulation device; 5- nitrogen exhaust valve; 6- drain valve; 7- tail gas exhaust device; 8- pressure sensing device. DETAILED DESCRIPTION

[0026] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0028] The present application provides an activation method for a fuel cell, wherein the fuel cell comprises an anode and a cathode disposed opposite to each other, and an anode catalyst layer disposed on a side of the anode close to the cathode. Figure 1 , the activation method of the fuel cell includes:

[0029] Step S10, receiving a shutdown instruction;

[0030] Step S20, shutting down the fuel cell system in response to the shutdown instruction, and leaving oxygen-containing gas on the anode side;

[0031] Step S30, restart the fuel cell system, and introduce hydrogen-containing gas to the anode side, so that the hydrogen-containing gas and the residual oxygen-containing gas on the anode side react to generate instantaneous current to strip off the residue on the surface of the anode catalyst layer and activate the fuel cell.

[0032] In the above-mentioned method for activating a fuel cell, after the fuel cell system is shut down in response to a shutdown command, oxygen-containing gas remains on the anode side, so that when the fuel cell system is restarted and hydrogen-containing gas is introduced into the anode side, the hydrogen-containing gas reacts with the oxygen-containing gas remaining on the anode side to generate a transient current, thereby stripping the residue on the surface of the anode catalyst layer. The residue stripped from the surface of the anode catalyst layer is discharged to the outside of the fuel cell along with the hydrogen-containing gas, restoring the active sites of the anode catalyst layer, thereby improving the performance of the fuel cell and achieving activation of the fuel cell. The above-mentioned method for activating a fuel cell can generate a transient current in the fuel cell for removing the residue on the surface of the anode catalyst layer, without the need for an external power supply outside the fuel cell, and correspondingly without the need to remove components in the fuel cell system, which simplifies the method for activating the fuel cell and is conducive to improving the activation efficiency of the fuel cell.

[0033] It should be noted that since the traditional activation method requires an external power supply and the removal of some components in the fuel cell system, online activation cannot be achieved. In addition, the external power supply method has strict operating requirements on the operator, and improper operation will create safety risks. The fuel cell activation method of the present application does not require an external power supply on the outside of the fuel cell, nor does it require the removal of components in the fuel cell system. Therefore, online activation can be achieved and safety risks are reduced.

[0034] In some embodiments, the fuel cell system further includes a control device and a gas supply device, the gas supply device is used to provide hydrogen-containing gas to the anode side of the fuel cell and oxygen-containing gas to the cathode side of the fuel cell, and the function of the control device includes but is not limited to controlling the introduction of hydrogen-containing gas and oxygen-containing gas. In step S10, the shutdown command is received by the control device.

[0035] In an alternative embodiment, see Figure 2 , between step S10 and step S20, that is, after receiving the shutdown instruction and before shutting down the fuel cell system in response to the shutdown instruction, the fuel cell activation method further includes:

[0036] Step S15, select to enter the fuel cell activation mode or the normal shutdown purge mode. Among them, oxygen-containing gas is allowed to remain on the anode side, and the fuel cell system is restarted, hydrogen-containing gas is introduced to the anode side, and the hydrogen-containing gas and the oxygen-containing gas remaining on the anode side react to generate instantaneous current to strip the residues on the surface of the anode catalyst layer and activate the fuel cell, all of which are performed in the fuel cell activation mode. That is, after receiving the shutdown command and before shutting down the fuel cell system in response to the shutdown command, a selection operation is also included to achieve the selection of the subsequent mode. When the subsequent mode is selected as the fuel cell activation mode, oxygen-containing gas remains on the anode side after shutting down the fuel cell system, so as to activate the fuel cell after restarting the fuel cell system; when the subsequent mode is selected as the normal shutdown purge mode, hydrogen-containing gas remains on the anode side after shutting down the fuel cell system.

[0037] In some embodiments, the fuel cell further includes a proton exchange membrane between the anode catalyst layer and the cathode, that is, the type of the fuel cell is a proton exchange membrane fuel cell. The core component of the proton exchange membrane fuel cell is a membrane electrode, which includes a cathode catalyst layer, a proton exchange membrane and an anode catalyst layer stacked in sequence, the cathode is located on the side of the cathode catalyst away from the proton exchange membrane, and the anode is located on the side of the anode catalyst away from the proton exchange membrane. In the proton exchange membrane fuel cell, step S20 shuts down the fuel cell system in response to the shutdown command and leaves oxygen-containing gas on the anode side, including: in the process of shutting down the fuel cell system in response to the shutdown command, continuously providing oxygen-containing gas to the cathode side; after receiving the shutdown command until the voltage of the fuel cell drops to a first threshold, continuously providing hydrogen-containing gas to the anode side; after the voltage of the fuel cell drops to the first threshold, the oxygen-containing gas on the cathode side penetrates through the proton exchange membrane to the anode side, and residual oxygen-containing gas is formed on the anode side; after the voltage of the fuel cell drops to a second threshold, shut down the fuel cell system; wherein the second threshold is less than the first threshold.

[0038] In other words, in step S20, after the control device receives the shutdown instruction, if it is selected to enter the fuel cell activation mode, the control device will control the gas supply device to continuously provide oxygen-containing gas to the cathode side and hydrogen-containing gas to the anode side, and the voltage of the fuel cell gradually decreases during the process; when the voltage of the fuel cell drops to the first threshold, the anode side stops introducing hydrogen-containing gas, while the cathode side continues to introduce oxygen-containing gas, which makes the cathode side and the anode side have a pressure difference. Under the action of the pressure difference, part of the oxygen-containing gas on the cathode side penetrates through the proton exchange membrane to the anode side, so that after the fuel cell system is shut down, oxygen-containing gas remains on the anode side. The above steps can effectively remove moisture inside the fuel cell by continuously providing oxygen-containing gas to the cathode side and hydrogen-containing gas to the anode side, and form residual oxygen-containing gas on the anode side without changing the ventilation type on the anode side, which also makes it unnecessary to adjust the ventilation type on the anode side back to hydrogen-containing gas after the fuel cell system is shut down and before the fuel cell system is restarted, and the operation is simple.

[0039] In step S20, after the control device receives the shutdown command, if it chooses to enter the normal shutdown purge mode, the control device will control the gas supply device to continuously supply oxygen-containing gas to the cathode side and hydrogen-containing gas to the anode side. During this process, the voltage of the fuel cell gradually decreases; when the voltage of the fuel cell drops to a first threshold value, the cathode side stops supplying oxygen-containing gas, while the anode side continues to supply hydrogen-containing gas, until the voltage of the fuel cell drops to a second threshold value, the anode side stops supplying hydrogen-containing gas, and the fuel cell system is shut down. At this time, the type of gas remaining on the anode side is hydrogen-containing gas.

[0040] Furthermore, the type of fuel cell is a proton exchange membrane fuel cell. In the process of shutting down the fuel cell system in response to the shutdown command, the gas pressure range of the oxygen-containing gas provided to the cathode side is 110kPa to 130kPa, such as 110kPa, 115kPa, 120kPa, 125kPa or 130kPa; the gas pressure range of the hydrogen-containing gas provided to the anode side is 120kPa to 140kPa, such as 120kPa, 125kPa, 130kPa, 135kPa or 140kPa. The gas pressure is positively correlated with the gas flow rate. If the gas pressure is too high, it is easy to break through the membrane electrode and destroy the fuel cell structure; if the gas pressure is too low, the moisture inside the fuel cell cannot be effectively removed. The above gas pressure range effectively removes the moisture inside the fuel cell while maintaining the integrity of the fuel cell structure.

[0041] In some embodiments, the first threshold value may be 30V-90V, such as 30V, 40V, 50V, 60V, 70V, 80V or 90V; the second threshold value may be 0V-30V, such as 0V, 5V, 10V, 15V, 20V, 25V or 30V. In other embodiments, the first threshold value and the second threshold value may also be other values. The specific values ​​of the first threshold value and the second threshold value may be selected according to the structure of the fuel cell, the setting of the fuel cell system, etc.

[0042] In some of the embodiments, the activation method of the fuel cell further includes: in step S20, after the voltage of the fuel cell drops to the first threshold, the fuel cell is connected to a pressure relief electrical element so that the voltage of the fuel cell drops to a second threshold. For example, in the fuel cell activation mode, after the voltage of the fuel cell drops to the first threshold, the anode side stops introducing hydrogen-containing gas, and the fuel cell is connected to the pressure relief electrical element; in the normal shutdown purge mode, after the voltage of the fuel cell drops to the first threshold, the cathode side stops introducing oxygen-containing gas, and the fuel cell is connected to the pressure relief electrical element. The pressure relief electrical element can quickly consume the voltage of the fuel cell, so that the voltage of the fuel cell is quickly reduced to the second threshold, thereby improving the efficiency of shutting down the fuel cell system. Specifically, the pressure relief electrical element includes but is not limited to a resistor.

[0043] In some embodiments, the oxygen-containing gas includes air, and the hydrogen-containing gas includes but is not limited to hydrogen. In the process of shutting down the fuel cell system in response to the shutdown command, the oxygen in the air reacts with the hydrogen element to generate water, and the nitrogen in the air does not participate in the reaction. The fuel cell is also connected to a drain valve and a nitrogen exhaust valve, and the switches of the drain valve and the nitrogen exhaust valve are controlled by a control device. The activation method of the fuel cell also includes: in step S20, after receiving the shutdown command and until the voltage of the fuel cell drops to a second threshold, the drain valve and the nitrogen exhaust valve are periodically opened to discharge nitrogen and water. The opening frequency of the drain valve can be 10HZ-50HZ, such as 10HZ, 15HZ, 20HZ, 25HZ, 30HZ, 35HZ, 40HZ, 45HZ or 50HZ; the opening frequency of the nitrogen exhaust valve can be 10HZ-50HZ, such as 10HZ, 15HZ, 20HZ, 25HZ, 30HZ, 35HZ, 40HZ, 45HZ or 50HZ; the specific opening frequencies of the nitrogen exhaust valve and the drain valve can be selected according to actual needs.

[0044] In some of the embodiments, the method for activating a fuel cell further includes: in step S20, in the process of shutting down the fuel cell system in response to a shutdown instruction, cooling the fuel cell so that the temperature of the fuel cell reaches room temperature, such as 20°C to 30°C.

[0045] It should be noted that the fuel cell system operates normally after restarting the fuel cell system and before receiving the shutdown command. During the normal operation of the fuel cell system, hydrogen-containing gas is introduced into the anode side of the fuel cell, oxygen-containing gas is introduced into the cathode side of the fuel cell, the drain valve is opened regularly to discharge the water generated by the reaction, and the cooling device cools the fuel cell to reduce the temperature of the fuel cell. When the oxygen-containing gas is air, the nitrogen exhaust valve is opened regularly to discharge nitrogen during the normal operation of the fuel cell system.

[0046] See also Figure 3 , the embodiment of the present application also provides a fuel cell system, including a fuel cell 1, a gas supply device 2 and a control device 3. The fuel cell 1 includes an anode and a cathode arranged relatively to each other, and an anode catalyst layer arranged on the side of the anode close to the cathode. The gas supply device 2 is configured to: provide hydrogen-containing gas to the anode side and oxygen-containing gas to the cathode side. The control device 3 is connected to the gas supply device 2, and the control device is configured to: in response to a shutdown instruction to shut down the fuel cell system, send a first control instruction to the gas supply device so that oxygen-containing gas remains on the anode side after shutting down the fuel cell system; and, in response to a restart instruction, send a second control instruction to the gas supply device so that hydrogen-containing gas is passed into the anode side, so that the hydrogen-containing gas and the oxygen-containing gas remaining on the anode side react to generate instantaneous current, and strip off the residue on the surface of the anode catalyst layer to activate the fuel cell.

[0047] In the above-mentioned fuel cell system, in response to the shutdown command, when shutting down the fuel cell system, the control device sends a first control command to the gas supply device, so that oxygen-containing gas remains on the anode side after shutting down the fuel cell system; in response to the restart command, the control device sends a second control command to the gas supply device, so that hydrogen-containing gas is passed into the anode side, and the hydrogen-containing gas reacts with the oxygen-containing gas remaining on the anode side to generate instantaneous current, thereby stripping the residue on the surface of the anode catalyst layer, restoring the active sites of the anode catalyst layer, and thus improving the performance of the fuel cell, and realizing the activation of the fuel cell. That is, the above-mentioned fuel cell system can realize the activation of the fuel cell without an external power supply.

[0048] It should be noted that, in order to improve power generation efficiency, a fuel cell system generally includes a plurality of fuel cells 1 , and the plurality of fuel cells 1 form a fuel cell stack.

[0049] In some embodiments, see Figure 4The gas supply device 2 includes a hydrogen source 21, a pressure regulating valve 22, a gas compression device 23, a gas cooling device 24, a humidifying device 25, a back pressure valve 26, a front stop valve 27, a rear stop valve 28, and a bypass valve 29. The hydrogen source 21 is connected to the fuel cell stack 11 to introduce hydrogen to the anode side of the fuel cell. The gas compression device 23, the gas cooling device 24, the humidifying device 25 and the fuel cell stack 11 are connected in sequence. After the gas compression device 23 compresses the air, the compressed air is transmitted to the gas cooling device 24 for cooling. The cooled compressed air is transmitted to the humidifying device 25 for humidification to meet the use requirements of the fuel cell stack 11, and then enters the fuel cell stack 11 through the pipeline where the front stop valve 27 is located for reaction, and the unreacted remaining air in the fuel cell stack 11 enters the humidifying device 25 through the pipeline where the rear stop valve 28 is located, and then is discharged from the humidifying device 25 through the pipeline where the back pressure valve 26 is located. The back pressure valve 26 is used to regulate the flow of compressed gas entering the fuel cell stack 11. The pipeline where the bypass valve 29 is located is connected to the gas cooling device 24, and the bypass valve 29 is used to prevent the air compressor from surging. After the fuel cell system is shut down, the front stop valve 27 and the rear stop valve 28 are closed to make the fuel cell stack 11 in a sealed state. The gas compression device 23 can be an air compressor, the gas cooling device 24 can be an intercooler, and the humidification device can be a humidifier.

[0050] In some embodiments, see Figure 4 , the fuel cell system further includes a circulation device 4, a nitrogen exhaust valve 5 and a drain valve 6. The circulation device 4 has an input end, a first output end, a second output end and a third output end, the fuel cell stack 11 is connected to the input end, the first output end is connected to the pipeline where the pressure regulating valve 22 is located, the second output end is connected to the drain valve 6, and the third output end is connected to the nitrogen exhaust valve 5. The water, unreacted hydrogen and nitrogen that do not participate in the reaction generated by the reaction of the fuel cell stack 11 enter the circulation device 4 through the input end, the unreacted hydrogen is transmitted to the pipeline where the pressure regulating valve 22 is located through the first output end, and then re-enters the fuel cell stack 11 to participate in the reaction, realizing the recycling of hydrogen, the water generated by the reaction is transmitted to the pipeline where the drain valve 6 is located through the second output end to be discharged from the fuel cell system, and the nitrogen that does not participate in the reaction is transmitted to the pipeline where the nitrogen exhaust valve 5 is located through the third output end to be discharged from the fuel cell system. The circulation device 4 can be a circulation pump.

[0051] In some embodiments, see Figure 4 The fuel cell system further includes an exhaust gas emission device 7, which is connected to a pipeline where the drain valve 6 is located, a pipeline where the nitrogen exhaust valve 5 is located, a pipeline where the bypass valve 29 is located, and a pipeline where the front stop valve 27 is located.

[0052] In some embodiments, see Figure 4The fuel cell system further includes a pressure sensor device 8 disposed at the oxygen-containing gas inlet, oxygen-containing gas outlet, hydrogen inlet, and hydrogen outlet of the fuel cell stack 11, for detecting the pressure at the oxygen-containing gas inlet, oxygen-containing gas outlet, hydrogen-containing gas inlet, and hydrogen-containing gas outlet of the fuel cell stack 11. The "gas pressure of the oxygen-containing gas" described in this application refers to the gas pressure at the oxygen-containing gas inlet of the fuel cell stack 11, and the "gas pressure of the hydrogen-containing gas" described in this application refers to the gas pressure at the hydrogen-containing gas inlet of the fuel cell stack 11.

[0053] In the present application, the control device can control the opening and closing of each component in the fuel cell system, the rotation speed of the gas compression device 23, the cooling efficiency of the gas cooling device 24, the humidification efficiency of the humidification device 25, the rotation speed of the circulation device 4, the opening of the pressure regulating valve 22, the opening of the back pressure valve 26, and the opening frequency of the nitrogen exhaust valve 5 and the water drain valve 6. The "fuel cell system shutdown" mentioned in the present application means that all components in the fuel cell system are closed.

[0054] In some embodiments, the fuel cell system further includes a selection device (not shown), which is connected to the control device, and the selection device is configured to: after the control device receives the shutdown command and before shutting down the fuel cell system in response to the shutdown command, send a selection command to the control device to enter the fuel cell activation mode or the normal shutdown purge mode, and the first control command and the second control command are generated in the fuel cell activation mode. In other words, the selection device is used to perform mode selection, and when the fuel cell activation mode is selected, the control device generates the first control command and the second control command.

[0055] Combine the following Figure 4 For the specific structure of the fuel cell system, see Figure 5 , a fuel cell activation method is fully described as an example:

[0056] Before the control device receives the shutdown command, the fuel cell system is in a normal working state: air is introduced into the cathode side, hydrogen is introduced into the anode side, the circulation device 4 operates at a preset speed, and the nitrogen exhaust valve 5 and the water drain valve 6 are opened regularly to discharge nitrogen and water regularly;

[0057] After receiving the shutdown command, the control device adjusts the compression strength of the gas compression device 23, the opening of the back pressure valve 26, the opening of the pressure regulating valve 22, the circulation efficiency of the circulation device 4, and the opening frequency of the nitrogen exhaust valve 5 and the water drain valve 6 to adjust the hydrogen flow and air flow into the fuel cell stack 11, and the fuel cell voltage gradually decreases;

[0058] When the fuel cell voltage drops to the first threshold, the fuel cell stack 11 is connected to the pressure relief resistor to quickly reduce the fuel cell voltage and enter the pressure relief state; at the same time, the hydrogen is stopped from entering the anode side, and the air is continuously introduced into the cathode side. Under the action of the pressure difference, the air on the cathode side diffuses to the anode side;

[0059] When the fuel cell voltage drops to a second threshold value, which is less than the first threshold value, the fuel cell system is shut down, and air remains on the anode side;

[0060] The control device receives the restart command, the fuel cell system restarts, and the fuel cell system resumes normal working state: air is introduced into the cathode side, hydrogen is introduced into the anode side, the circulation device 4 works at a preset speed, and the nitrogen exhaust valve 5 and the water drain valve 6 are opened regularly to regularly discharge nitrogen and water. When the fuel cell system is restarted and hydrogen-containing gas is introduced into the anode side, the hydrogen-containing gas reacts with the residual oxygen-containing gas on the anode side to generate instantaneous current, thereby stripping the residue on the surface of the anode catalyst layer and restoring the active sites of the anode catalyst layer.

[0061] In a specific fuel cell system, the fuel cell stack includes 345 hydrogen-oxygen fuel cells connected in series, and the hydrogen-oxygen fuel cells are proton exchange membrane fuel cells. Before receiving the shutdown command, the above-mentioned fuel cell system has a power generation power of 70kW-72kW at the rated point density of the fuel cell system; after the fuel cell system is shut down and restarted, the power generation power of the fuel cell system at the rated point density is 73kW-75kW. It can be seen that the activation method of the fuel cell provided in the present application can increase the power generation power of the fuel cell system and realize the activation of the fuel cell.

[0062] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0063] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for activating a fuel cell, characterized in that: The fuel cell comprises an anode and a cathode arranged opposite to each other, and an anode catalyst layer arranged on a side of the anode close to the cathode; the activation method of the fuel cell comprises: Receive shutdown command; In response to the shutdown instruction, shutting down the fuel cell system and leaving oxygen-containing gas on the anode side; Restart the fuel cell system, introduce hydrogen-containing gas into the anode side, and make the hydrogen-containing gas react with the oxygen-containing gas remaining on the anode side to generate instantaneous current to strip the residue on the surface of the anode catalyst layer and activate the fuel cell.

2. The method for activating a fuel cell according to claim 1, characterized in that: Also includes: After receiving the shutdown command and before shutting down the fuel cell system in response to the shutdown command, selecting to enter a fuel cell activation mode or a normal shutdown purge mode; Among them, allowing oxygen-containing gas to remain on the anode side and restarting the fuel cell system to pass hydrogen-containing gas to the anode side so that the hydrogen-containing gas and the oxygen-containing gas remaining on the anode side react to generate instantaneous current to strip off the residues on the surface of the anode catalyst layer and activate the fuel cell are all carried out in the fuel cell activation mode.

3. The method for activating a fuel cell according to claim 1 or 2, characterized in that: The fuel cell further includes a proton exchange membrane between the anode catalyst layer and the cathode; shutting down the fuel cell system in response to the shutdown instruction and leaving oxygen-containing gas on one side of the anode, comprising: In the process of shutting down the fuel cell system in response to the shutdown instruction, continuously supplying oxygen-containing gas to the cathode side; After receiving the shutdown instruction, until the voltage of the fuel cell drops to a first threshold, continuously supplying hydrogen-containing gas to the anode side; After the voltage of the fuel cell decreases to the first threshold, the oxygen-containing gas on the cathode side permeates through the proton exchange membrane to the anode side, forming residual oxygen-containing gas on the anode side.

4. The method for activating a fuel cell according to claim 3, characterized in that: Also includes: After the voltage of the fuel cell decreases to a second threshold, the fuel cell system is shut down; wherein the second threshold is smaller than the first threshold.

5. The method for activating a fuel cell according to claim 4, characterized in that: Also includes: After the voltage of the fuel cell is reduced to the first threshold, the fuel cell is connected to a pressure relief element to reduce the voltage of the fuel cell to the second threshold.

6. The method for activating a fuel cell according to claim 4, characterized in that: The oxygen-containing gas includes air; the fuel cell is also connected to a drain valve and a nitrogen exhaust valve; the activation method of the fuel cell also includes: After receiving the shutdown instruction and until the voltage of the fuel cell decreases to the second threshold, the water discharge valve and the nitrogen discharge valve are periodically opened to discharge nitrogen and water.

7. The method for activating a fuel cell according to claim 3, characterized in that: Also includes: In the process of shutting down the fuel cell system in response to the shutdown instruction, the fuel cell is cooled so that the temperature of the fuel cell reaches room temperature.

8. The method for activating a fuel cell according to claim 3, characterized in that: In the process of shutting down the fuel cell system in response to the shutdown instruction, the gas pressure range of the oxygen-containing gas provided to the cathode side is 110kPa-130kPa; the gas pressure range of the hydrogen-containing gas provided to the anode side is 120kPa-140kPa.

9. A fuel cell system, characterized in that: include: A fuel cell comprises an anode and a cathode arranged opposite to each other, and an anode catalyst layer arranged on a side of the anode close to the cathode; A gas supply device is configured to: supply hydrogen-containing gas to the anode side and oxygen-containing gas to the cathode side; A control device is connected to the gas supply device and is configured to: in response to a shutdown command, during the process of shutting down the fuel cell system, send a first control command to the gas supply device so that oxygen-containing gas remains on the anode side after the fuel cell system is shut down; and in response to a restart command, send a second control command to the gas supply device so that hydrogen-containing gas is passed into the anode side, so that the hydrogen-containing gas reacts with the oxygen-containing gas remaining on the anode side to generate instantaneous current, and removes residues on the surface of the anode catalyst layer to activate the fuel cell.

10. The fuel cell system according to claim 9, characterized in that: Also includes: A selection device connected to the control device and configured to: after the control device receives the shutdown instruction and before shutting down the fuel cell system in response to the shutdown instruction, send a selection instruction to the control device to enter a fuel cell activation mode or a normal shutdown purge mode; Wherein, the first control instruction and the second control instruction are generated in the fuel cell activation mode.

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