A fuel cell stack activation method

Abstract

This invention discloses a method for activating a fuel cell stack, relating to the field of fuel cell stack testing. The key points are: first, after loading the fuel cell stack to the highest current density corresponding to the polarization curve; second, reducing the cathode stoichiometry by a first reduction step size, performing multiple reduction steps followed by a first running time, and then restoring to the normal cathode stoichiometry, with each step's running time being a second running time; third, increasing the cathode stoichiometry by a first increase step size, performing multiple increase steps followed by a third running time, and then restoring to the normal cathode stoichiometry, with each step's running time being a fourth running time; repeating the above operations 1-3 times completes the activation of the fuel cell stack. This invention can shorten the fuel cell stack activation time, increase the activation speed, improve the activation efficiency, save hydrogen consumption, reduce the cost of fuel cell stack activation, and prevent damage to the fuel cell stack.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell stack testing, and in particular to a fuel cell stack activation method. Background Art

[0002] After the fuel cell stack is assembled, it is installed on the stack test bench. Since the electrocatalyst has not worked for a long time, an oxidation reaction will occur on the catalyst surface in the atmosphere. The catalytic performance of the formed oxide is low. It is necessary to expose the active sites of the reaction through activation to improve the performance of the stack. Activation can open up the electron transmission channel of the electrochemical reaction. After activation, the performance and consistency of the stack will be greatly improved. At the same time, water is generated through the reaction. The hydrogen ions generated by the anode reaction combine with water to form hydronium ions, which pass through the proton exchange membrane that can only pass hydrogen ions to open up its proton and water transmission channels, thereby restoring the performance of the fuel cell to the normal working performance level. The activation process of the fuel cell mainly adopts the online activation method, using hydrogen and air to operate according to the designed activation conditions, and pulling and loading according to the conditions for many times. Usually after pulling and loading 3 to 5 times, the voltage-current density curve drawn during each pulling and loading is compared. When the performance difference between the two curves is very small, it can be considered that the activation has been completed, that is, the average voltage difference is within 5mV, and the activation can be considered to be completed. The activated fuel cell stack can be used for research and development or for the assembly of fuel cell systems. This method is safe, will not damage the stack, and the activation effect is more intuitive, but this method is time-consuming and consumes a large amount of hydrogen. If the stack is long, the amount of hydrogen consumed is relatively large. The mass production of the stack requires the exploration of a low-cost and fast activation method. In view of the above problems, it is necessary to study and design a new fuel cell stack activation method to overcome the problems existing in existing fuel cells. Summary of the invention

[0003] In order to solve the problems of slow activation speed, low activation efficiency and large hydrogen consumption in the existing fuel cell stack activation method, the present invention provides a fuel cell stack activation method.

[0004] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a fuel cell stack activation method, comprising the following steps:

[0005] S1. Install the fuel cell stack on the stack test bench;

[0006] S2. introducing dry nitrogen into the anode of the fuel cell stack at a first introduction speed, and introducing dry nitrogen into the cathode of the fuel cell stack at a second introduction speed, adjusting the anode pressure and the cathode pressure synchronously to a first pressure value, and stopping the introduction of dry nitrogen into the anode and the cathode at the same time after the dry nitrogen is purged into the anode and the cathode;

[0007] S3. introducing wet nitrogen into the anode of the fuel cell stack at a third introduction speed, and introducing wet nitrogen into the cathode of the fuel cell stack at a fourth introduction speed, adjusting the anode pressure and the cathode pressure to a second pressure value synchronously, and stopping the introduction of wet nitrogen into the anode and the cathode at the same time after the wet nitrogen purges the anode and the cathode;

[0008] S4. Turn on the cooling water pump and the circulating water pump, set the water flow rate of the circulating water pump to the first water flow rate, introduce hydrogen into the anode through the constant pressure-hydrogen reflux pump mode, introduce air into the cathode through the stoichiometric ratio mode, set the anode stack pressure and the cathode stack pressure to the first stack pressure, heat the water temperature of the circulating water pump to the first water temperature, set the hydrogen stack humidity to be consistent with the hydrogen stack humidity at the highest point of the polarization curve, set the air stack humidity to be consistent with the air stack humidity at the highest point of the polarization curve, and set the heating tape insulation at the anode and cathode air inlets to the first temperature;

[0009] S5. Activate the fuel cell stack, the cathode stoichiometric ratio is the stoichiometric ratio corresponding to each current density under the test condition of the polarization curve of the fuel cell stack, load the fuel cell stack in a constant current mode, and before loading the next current density, use the cathode gas volume and anode reflux pump speed corresponding to the next current density to run for 1 to 3 minutes, then adjust the circulating water flow, anode pressure and cathode pressure to the circulating water flow, anode pressure and cathode pressure corresponding to the next current density, until the fuel cell stack is loaded to the highest current density corresponding to the polarization curve;

[0010] S6. The cathode stoichiometric ratio is reduced, the reduction step is the first reduction step, the first operation time is reduced for multiple steps, and then restored to the normal cathode stoichiometric ratio, wherein the operation time of each step is the second operation time;

[0011] S7. Increase the cathode stoichiometry ratio, increase the step length to the first increase step length, increase the number of steps to run the third operation time, and then return to the normal cathode stoichiometry ratio, wherein the operation time of each step is the fourth operation time;

[0012] S8. After repeating step S6 and step S7 1 to 3 times, activation of the fuel cell stack is completed;

[0013] S9. The current density of the fuel cell stack is reduced to 0, and then the hydrogen and air are stopped and the cooling water pump and the circulating water pump are turned off;

[0014] S10. Introduce nitrogen into the hydrogen cavity and air cavity of the fuel cell stack for purging.

[0015] According to a fuel cell stack activation method of some embodiments of the present invention, in step S2, the first introduction rate is 50-100 splm, the second introduction rate is 70-150 slpm, the first pressure value is 0.5-1.0 bar, and dry nitrogen is purged at the anode and cathode for 3-5 minutes.

[0016] According to a fuel cell stack activation method of some embodiments of the present invention, in step S3, the third introduction rate is 50-100 splm, the fourth introduction rate is 70-150 slpm, the second pressure value is 0.5-1.0 bar, the relative humidity of the wet nitrogen is 95%, and the wet nitrogen is purged at the anode and cathode for 3-5 minutes.

[0017] According to a fuel cell stack activation method of some embodiments of the present invention, in step S4, the first water flow rate is 20-80 L / min, the first stack pressure is 0.4-0.6 bar, the first water temperature is 60-80°C, and the first temperature is 60-80°C.

[0018] According to a fuel cell stack activation method of some embodiments of the present invention, in step S6, the first reduction step length is 0.1 to 0.3, the number of reduction steps is 1 to 3 steps, the first operating time is 2 to 5 minutes, and the second operating time is 1 to 3 minutes.

[0019] According to a fuel cell stack activation method of some embodiments of the present invention, in step S6, the first reduction step length is 0.2.

[0020] According to a fuel cell stack activation method of some embodiments of the present invention, in step S7, the first increase step is 0.1 to 0.3, the number of increase steps is 1 to 3 steps, the third operation time is 2 to 5 minutes, and the fourth operation time is 1 to 3 minutes.

[0021] According to a fuel cell stack activation method of some embodiments of the present invention, in step S7, the first increase step size is 0.2.

[0022] According to a fuel cell stack activation method of some embodiments of the present invention, in step S10, wet nitrogen is introduced into the hydrogen chamber and air chamber of the fuel cell stack at 70 to 150 slpm and purged for 150 to 300 s, and then dry nitrogen is introduced into the hydrogen chamber and air chamber of the fuel cell stack at 70 to 150 slpm and purged for 30 to 50 s.

[0023] A fuel cell stack activation method of the present invention shortens the fuel cell stack activation time, increases the activation speed of the fuel cell stack, can improve the activation efficiency of the fuel cell stack, saves hydrogen usage, and reduces the cost of fuel cell stack activation. In addition, the method of the present invention has high safety and will not cause damage to the fuel cell stack. The fuel cell stack activation method of the present invention is conducive to the mass production of fuel cell stacks. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a curve of current density and stoichiometric ratio changing with time at the highest activation current density of the fuel cell stack according to an embodiment of the present invention;

[0025] Figure 2 is a curve of current density and range variation over time at the highest activation current density of a fuel cell stack according to an embodiment of the present invention;

[0026] Figure 3 It is a comparison chart of the fuel cell stack performance after conventional activation and rapid activation in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0028] Example 1

[0029] A fuel cell stack activation method of this embodiment includes the following steps:

[0030] S1. Install the fuel cell stack on the stack test bench;

[0031] S2. introducing dry nitrogen into the anode of the fuel cell stack at a first introduction speed, and introducing dry nitrogen into the cathode of the fuel cell stack at a second introduction speed, adjusting the anode pressure and the cathode pressure synchronously to the first pressure value, and stopping the introduction of dry nitrogen into the anode and the cathode at the same time after the dry nitrogen is purged into the anode and the cathode;

[0032] Specifically, the first introduction speed is 50-100 splm, the second introduction speed is 70-150 slpm, the first pressure value is 0.5-1.0 bar, and the dry nitrogen gas is purged for 3-5 minutes at the anode and cathode. When the dry nitrogen gas is introduced into the cathode and the anode, it should be noted that the cathode and the anode need to be pressurized synchronously to avoid damaging the membrane electrode of the fuel cell stack.

[0033] S3. introducing wet nitrogen into the anode of the fuel cell stack at a third introduction speed, and introducing wet nitrogen into the cathode of the fuel cell stack at a fourth introduction speed, adjusting the anode pressure and the cathode pressure to the second pressure value synchronously, and stopping the introduction of wet nitrogen into the anode and the cathode at the same time after the wet nitrogen purges the anode and the cathode;

[0034] Specifically, the third introduction speed is 50-100 splm, the fourth introduction speed is 70-150 slpm, the second pressure value is 0.5-1.0 bar, the relative humidity of the wet nitrogen is 95%, and the wet nitrogen purges the anode and the cathode for 3-5 minutes. When the wet nitrogen is introduced into the cathode and the anode, it should be noted that the cathode and the anode need to be boosted synchronously to avoid damaging the membrane electrode of the fuel cell stack;

[0035] S4. Turn on the cooling water pump and the circulating water pump, set the water flow rate of the circulating water pump to the first water flow rate, introduce hydrogen into the anode through the constant pressure-hydrogen reflux pump mode, introduce air into the cathode through the stoichiometric ratio mode, set the anode stack pressure and the cathode stack pressure to the first stack pressure, heat the water temperature of the circulating water pump to the first water temperature, set the hydrogen stack humidity to be consistent with the hydrogen stack humidity at the highest point of the polarization curve, set the air stack humidity to be consistent with the air stack humidity at the highest point of the polarization curve, and set the heating tape insulation at the anode and cathode air inlets to the first temperature;

[0036] Specifically, the first water flow rate is 20-80 L / min, the first stack pressure is 0.4-0.6 bar, the first water temperature is 60-80° C., the first temperature is 60-80° C., and the polarization curve is measured by other fuel cell stacks of the same specifications produced in the same batch as the activated fuel cell stack in this embodiment;

[0037] S5. Activate the fuel cell stack, load the fuel cell stack in a constant current mode, introduce hydrogen into the anode through a constant pressure-hydrogen reflux pump mode, and introduce air into the cathode in a stoichiometric ratio mode, wherein the cathode stoichiometric ratio is the stoichiometric ratio corresponding to each current density under the test conditions of the polarization curve of the fuel cell stack, and load the fuel cell stack in a constant current mode. Before loading the next current density, use the cathode gas volume and anode reflux pump speed corresponding to the next current density for 1 to 3 minutes, and then adjust the circulating water flow, anode pressure, and cathode pressure to the circulating water flow, anode pressure, and cathode pressure corresponding to the next current density, until the fuel cell stack is loaded to the highest current density corresponding to the polarization curve;

[0038] S6. The cathode stoichiometric ratio is reduced, the reduction step is the first reduction step, the first operation time is reduced for multiple steps, and then restored to the normal cathode stoichiometric ratio, wherein the operation time of each step is the second operation time;

[0039] Specifically, the first reduction step length is 0.1 to 0.3, the number of reduction steps is 1 to 3 steps, the first operation time is 2 to 5 minutes, and the second operation time is 1 to 3 minutes;

[0040] S7. Increase the cathode stoichiometry ratio, increase the step length to the first increase step length, increase the number of steps to run the third operation time, and then return to the normal cathode stoichiometry ratio, wherein the operation time of each step is the fourth operation time;

[0041] Specifically, the first increase step length is 0.1 to 0.3, the increase step number is 1 to 3 steps, the third operation time is 2 to 5 minutes, and the fourth operation time is 1 to 3 minutes;

[0042] S8. After repeating step S6 and step S7 1 to 3 times, the activation of the fuel cell stack is completed; in this embodiment, the activation completion standard can be achieved without the need for multiple rounds of loading similar to the traditional activation method;

[0043] S9. The current density of the fuel cell stack is reduced to 0, and then the hydrogen and air are stopped and the cooling water pump and the circulating water pump are turned off;

[0044] S10. Nitrogen is introduced into the hydrogen chamber and the air chamber of the fuel cell stack for purging;

[0045] Specifically, wet nitrogen is introduced into the hydrogen cavity and air cavity of the fuel cell stack at 70-150 slpm for 150-300 seconds, and then dry nitrogen is introduced into the hydrogen cavity and air cavity of the fuel cell stack at 70-150 slpm for 30-50 seconds.

[0046] Before carrying out the activation method of this embodiment, a sample is taken from a mass-produced fuel cell stack to detect its average voltage performance under normal operating conditions when the activation is completed, which is used as the activation completion standard. Figure 1 is the curve of current density and stoichiometric ratio changing with time at the highest activation current density of the fuel cell stack of this embodiment, Figure 2 The current density and range curves of the fuel cell stack at the highest activation current density of this embodiment are as a function of time. The range represents the voltage difference between the highest voltage battery and the lowest voltage battery in the stack, which reflects the uniformity of the performance of the fuel cell stack. When the method of this embodiment is used for the activation, the time used is 30 minutes to 40 minutes. This embodiment only needs to run one round of activation, and the total time is 30 to 40 minutes. The traditional activation time is 1.5 hours per activation, and three rounds of activation are required, with a total time of 4.5 hours. The activation method of this embodiment can greatly shorten the total activation time of the fuel cell stack, increase the activation speed of the fuel cell stack, and reduce the consumption of hydrogen. Figure 3It is a comparison chart of the fuel cell stack performance after conventional activation and rapid activation in an embodiment of the present invention. It can be seen that after the fuel cell stack is activated using the method of the present invention, the performance of the fuel cell stack is slightly different from that of the fuel cell stack after using the conventional activation method.

[0047] As a preference of this embodiment, when activating the fuel cell stack, this embodiment uses a hydrogen source as a hydrogen supply source, an air compressor as an air supply source, a nitrogen bottle group to provide nitrogen for boosting, maintaining pressure and purging, and deionized water to provide moisture during activation to moisten the gas that needs to be introduced into the fuel cell stack, a stack test bench and its ancillary equipment.

[0048] When the fuel cell stack is loaded, when it is running at each current density, various parameters inside the fuel cell stack, such as gas flow, gas pressure, inlet temperature and outlet temperature, are kept constant, which can also ensure that the power generation process of the fuel cell stack is relatively stable. It is usually hoped that the fuel cell stack can have a stable performance output during operation. However, if the fuel cell stack is activated according to the parameters unchanged at a certain current density, then at the same current density, the possibility of activating the active sites on the surface of the catalyst inside the membrane electrode that has not been activated will be reduced, resulting in a lower probability of activation inside the stack. Therefore, the efficiency of the fuel cell stack reaction is improved by using the "hunger-satiation state". Since the overpotential of the electro-oxidation reaction of hydrogen on the membrane electrode in the fuel cell stack is small, the amount of catalyst on the membrane electrode is also small, while the overpotential of the redox reaction on the cathode side is large, and the amount of catalyst is large, the cathode catalyst needs to be fully activated. Therefore, the activation of the fuel cell is mainly the activation of the cathode electrocatalyst. Fuel cell stack activation is divided into constant current natural activation, constant current forced activation, variable current forced activation and constant voltage activation. Constant voltage activation can effectively reduce the agglomeration of catalysts during activation, and can avoid slow carbon corrosion caused by high potential by setting a lower voltage.

[0049] The traditional activation method is to load the fuel cell stack to the highest current density that can be achieved at the set safety value, and then continue to operate for 20 to 40 minutes. When operating at a high current density, a large amount of liquid water will be generated. The liquid water will increase the mass transfer resistance between the gas-solid phases inside the membrane electrode, affecting the uniformity of contact between the reaction substrate and the active center of the catalyst. In the traditional activation method, since all parameters are fixed, the physical and electrochemical reaction states of the reaction interface are in a steady state or a quasi-steady state that changes slowly, and the active points of all catalysts cannot be quickly and effectively exposed. However, this embodiment reduces and increases the stoichiometric ratio. When the stoichiometric ratio of the reaction gas is changed, the gas volume also changes, and the gas-liquid state of different flow channels inside the stack changes accordingly. Reducing the gas volume helps to change the steady state of the catalyst, and increasing the stoichiometric ratio helps to discharge liquid water and reduce the mass transfer resistance of the gas. These changes can break the steady state and redistribute the active center sites where the reaction occurs, thereby accelerating the activation process of the stack as a whole.

[0050] Example 2

[0051] A fuel cell stack activation method of this embodiment includes the following steps:

[0052] S1. Install the fuel cell stack on the stack test bench;

[0053] S2. Dry nitrogen is introduced into the anode of the fuel cell stack at 50-100 splm, and dry nitrogen is introduced into the cathode of the fuel cell stack at 70-150 slpm, and the anode pressure and cathode pressure are adjusted to 0.5-1.0 bar simultaneously. After the anode and cathode are purged with dry nitrogen for 3-5 minutes, the introduction of dry nitrogen at the anode and cathode is stopped at the same time; note that when dry nitrogen is introduced into the cathode and anode, the cathode and anode need to be pressurized synchronously to avoid damaging the membrane electrode of the fuel cell stack;

[0054] S3. Wet nitrogen is introduced into the anode of the fuel cell stack at 50-100 splm, and wet nitrogen is introduced into the cathode of the fuel cell stack at 70-150 slpm, and the anode pressure and cathode pressure are adjusted to 0.5-1.0 bar simultaneously. After the wet nitrogen is purged into the anode and cathode for 3-5 minutes, the introduction of wet nitrogen into the anode and cathode is stopped at the same time; it is noted that when wet nitrogen is introduced into the cathode and anode, the cathode and anode need to be pressurized synchronously to avoid damaging the membrane electrode of the fuel cell stack;

[0055] S4. Turn on the cooling water pump and the circulating water pump, set the water flow rate of the circulating water pump to 20-80 L / min, introduce hydrogen into the anode through the constant pressure-hydrogen reflux pump mode, and introduce air into the cathode in the stoichiometric ratio mode. The anode inlet pressure and the cathode inlet pressure are both set to 0.4-0.6 bar, and the water temperature of the circulating water pump is heated to 60-80°C. The hydrogen inlet humidity is set to be consistent with the hydrogen inlet humidity at the highest point of the polarization curve, and the air inlet humidity is set to be consistent with the air inlet humidity at the highest point of the polarization curve. The heating belt insulation at the anode and cathode air inlets is set to 60-80°C, wherein the polarization curve is measured by other fuel cell stacks of the same specification produced in the same batch as the activated fuel cell stack in this embodiment;

[0056] S5. Activate the fuel cell stack, load the fuel cell stack in a constant current mode, introduce hydrogen into the anode through a constant pressure-hydrogen reflux pump mode, and introduce air into the cathode in a stoichiometric ratio mode, wherein the cathode stoichiometric ratio is the stoichiometric ratio corresponding to each current density under the test conditions of the polarization curve of the fuel cell stack, and load the fuel cell stack in a constant current mode. Before loading the next current density, use the cathode gas volume and anode reflux pump speed corresponding to the next current density for 1 to 3 minutes, and then adjust the circulating water flow, anode pressure, and cathode pressure to the circulating water flow, anode pressure, and cathode pressure corresponding to the next current density, until the fuel cell stack is loaded to the highest current density corresponding to the polarization curve;

[0057] S6. Reduce the cathode stoichiometric ratio, set the reduction step to 0.1, run for 2 to 5 minutes after reducing by 3 steps, and then restore to the normal cathode stoichiometric ratio, wherein the running time of each step is 1 to 3 minutes;

[0058] S7. Increase the cathode stoichiometric ratio, set the increase step to 0.1, increase by 3 steps, run for 2 to 5 minutes, and then return to the normal cathode stoichiometric ratio, wherein the running time of each step is 1 to 3 minutes;

[0059] S8. After repeating step S6 and step S7 1 to 3 times, the activation of the fuel cell stack is completed; the time used for the activation in the method of this embodiment is 30min to 40min, and the activation completion standard can be reached;

[0060] S9. The current density of the fuel cell stack is reduced to 0, and then the hydrogen and air are stopped and the cooling water pump and the circulating water pump are turned off;

[0061] S10. Introduce nitrogen into the hydrogen cavity and air cavity of the fuel cell stack for purge. After passing wet nitrogen at 70 to 150 slpm for 150 to 300 seconds, pass dry nitrogen at 70 to 150 slpm for 30 to 50 seconds.

[0062] Example 3

[0063] A fuel cell stack activation method of this embodiment includes the following steps:

[0064] S1. Install the fuel cell stack on the stack test bench;

[0065] S2. Dry nitrogen is introduced into the anode of the fuel cell stack at 50-100 splm, and dry nitrogen is introduced into the cathode of the fuel cell stack at 70-150 slpm, and the anode pressure and cathode pressure are adjusted to 0.5-1.0 bar simultaneously. After the anode and cathode are purged with dry nitrogen for 3-5 minutes, the introduction of dry nitrogen at the anode and cathode is stopped at the same time; note that when dry nitrogen is introduced into the cathode and anode, the cathode and anode need to be pressurized synchronously to avoid damaging the membrane electrode of the fuel cell stack;

[0066] S3. Wet nitrogen is introduced into the anode of the fuel cell stack at 50-100 splm, and wet nitrogen is introduced into the cathode of the fuel cell stack at 70-150 slpm, and the anode pressure and cathode pressure are adjusted to 0.5-1.0 bar simultaneously. After the wet nitrogen is purged into the anode and cathode for 3-5 minutes, the introduction of wet nitrogen into the anode and cathode is stopped at the same time; it is noted that when wet nitrogen is introduced into the cathode and anode, the cathode and anode need to be pressurized synchronously to avoid damaging the membrane electrode of the fuel cell stack;

[0067] S4. Turn on the cooling water pump and the circulating water pump, set the water flow rate of the circulating water pump to 20-80 L / min, introduce hydrogen into the anode through the constant pressure-hydrogen reflux pump mode, and introduce air into the cathode in the stoichiometric ratio mode. The anode inlet pressure and the cathode inlet pressure are both set to 0.4-0.6 bar, and the water temperature of the circulating water pump is heated to 60-80°C. The hydrogen inlet humidity is set to be consistent with the hydrogen inlet humidity at the highest point of the polarization curve, and the air inlet humidity is set to be consistent with the air inlet humidity at the highest point of the polarization curve. The heating belt insulation at the anode and cathode air inlets is set to 60-80°C, wherein the polarization curve is measured by other fuel cell stacks of the same specification produced in the same batch as the activated fuel cell stack in this embodiment;

[0068] S5. Activate the fuel cell stack, load the fuel cell stack in a constant current mode, introduce hydrogen into the anode through a constant pressure-hydrogen reflux pump mode, and introduce air into the cathode in a stoichiometric ratio mode, wherein the cathode stoichiometric ratio is the stoichiometric ratio corresponding to each current density under the test conditions of the polarization curve of the fuel cell stack, and load the fuel cell stack in a constant current mode. Before loading the next current density, use the cathode gas volume and anode reflux pump speed corresponding to the next current density for 1 to 3 minutes, and then adjust the circulating water flow, anode pressure, and cathode pressure to the circulating water flow, anode pressure, and cathode pressure corresponding to the next current density, until the fuel cell stack is loaded to the highest current density corresponding to the polarization curve;

[0069] S6. Reduce the cathode stoichiometric ratio, set the reduction step to 0.2, reduce 1 to 3 steps, run for 2 to 5 minutes, and then restore to the normal cathode stoichiometric ratio, wherein the running time of each step is 1 to 3 minutes;

[0070] S7. Increase the cathode stoichiometric ratio, set the increase step to 0.2, increase 1 to 3 steps, run for 2 to 5 minutes, and then return to the normal cathode stoichiometric ratio, wherein the running time of each step is 1 to 3 minutes;

[0071] S8. After repeating step S6 and step S7 1 to 3 times, the activation of the fuel cell stack is completed; the time used for the activation in the method of this embodiment is 30min to 40min, and the activation completion standard can be reached;

[0072] S9. The current density of the fuel cell stack is reduced to 0, and then the hydrogen and air are stopped and the cooling water pump and the circulating water pump are turned off;

[0073] S10. Introduce nitrogen into the hydrogen cavity and air cavity of the fuel cell stack for purge. After passing wet nitrogen at 70 to 150 slpm for 150 to 300 seconds, pass dry nitrogen at 70 to 150 slpm for 30 to 50 seconds.

[0074] Example 4

[0075] A fuel cell stack activation method of this embodiment includes the following steps:

[0076] S1. Install the fuel cell stack on the stack test bench;

[0077] S2. Dry nitrogen is introduced into the anode of the fuel cell stack at 50-100 splm, and dry nitrogen is introduced into the cathode of the fuel cell stack at 70-150 slpm, and the anode pressure and cathode pressure are adjusted to 0.5-1.0 bar simultaneously. After the anode and cathode are purged with dry nitrogen for 3-5 minutes, the introduction of dry nitrogen at the anode and cathode is stopped at the same time; note that when dry nitrogen is introduced into the cathode and anode, the cathode and anode need to be pressurized synchronously to avoid damaging the membrane electrode of the fuel cell stack;

[0078] S3. Wet nitrogen is introduced into the anode of the fuel cell stack at 50-100 splm, and wet nitrogen is introduced into the cathode of the fuel cell stack at 70-150 slpm, and the anode pressure and cathode pressure are adjusted to 0.5-1.0 bar simultaneously. After the wet nitrogen is purged into the anode and cathode for 3-5 minutes, the introduction of wet nitrogen into the anode and cathode is stopped at the same time; it is noted that when wet nitrogen is introduced into the cathode and anode, the cathode and anode need to be pressurized synchronously to avoid damaging the membrane electrode of the fuel cell stack;

[0079] S4. Turn on the cooling water pump and the circulating water pump, set the water flow rate of the circulating water pump to 20-80 L / min, introduce hydrogen into the anode through the constant pressure-hydrogen reflux pump mode, and introduce air into the cathode in the stoichiometric ratio mode. The anode inlet pressure and the cathode inlet pressure are both set to 0.4-0.6 bar, and the water temperature of the circulating water pump is heated to 60-80°C. The hydrogen inlet humidity is set to be consistent with the hydrogen inlet humidity at the highest point of the polarization curve, and the air inlet humidity is set to be consistent with the air inlet humidity at the highest point of the polarization curve. The heating belt insulation at the anode and cathode air inlets is set to 60-80°C, wherein the polarization curve is measured by other fuel cell stacks of the same specification produced in the same batch as the activated fuel cell stack in this embodiment;

[0080] S5. Activate the fuel cell stack, load the fuel cell stack in a constant current mode, introduce hydrogen into the anode through a constant pressure-hydrogen reflux pump mode, and introduce air into the cathode in a stoichiometric ratio mode, wherein the cathode stoichiometric ratio is the stoichiometric ratio corresponding to each current density under the test conditions of the polarization curve of the fuel cell stack, and load the fuel cell stack in a constant current mode. Before loading the next current density, use the cathode gas volume and anode reflux pump speed corresponding to the next current density for 1 to 3 minutes, and then adjust the circulating water flow, anode pressure, and cathode pressure to the circulating water flow, anode pressure, and cathode pressure corresponding to the next current density, until the fuel cell stack is loaded to the highest current density corresponding to the polarization curve;

[0081] S6. Reduce the cathode stoichiometric ratio, set the reduction step to 0.3, run for 2 to 5 minutes after reducing 1 to 3 steps, and then restore to the normal cathode stoichiometric ratio, wherein the running time of each step is 1 to 3 minutes;

[0082] S7. Increase the cathode stoichiometric ratio, set the increase step to 0.3, increase 1 to 3 steps, run for 2 to 5 minutes, and then return to the normal cathode stoichiometric ratio, wherein the running time of each step is 1 to 3 minutes;

[0083] S8. After repeating step S6 and step S7 1 to 3 times, the activation of the fuel cell stack is completed; the time used for the activation in the method of this embodiment is 30min to 40min, and the activation completion standard can be reached;

[0084] S9. The current density of the fuel cell stack is reduced to 0, and then the hydrogen and air are stopped and the cooling water pump and the circulating water pump are turned off;

[0085] S10. Introduce nitrogen into the hydrogen cavity and air cavity of the fuel cell stack for purge. After passing wet nitrogen at 70 to 150 slpm for 150 to 300 seconds, pass dry nitrogen at 70 to 150 slpm for 30 to 50 seconds.

[0086] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A fuel cell stack activation method, characterized in that: The steps include: S1. Install the fuel cell stack on the stack test bench; S2. introducing dry nitrogen into the anode of the fuel cell stack at a first introduction rate, and introducing dry nitrogen into the cathode of the fuel cell stack at a second introduction rate, adjusting the anode pressure and the cathode pressure to a first pressure value synchronously, and stopping the introduction of dry nitrogen into the anode and the cathode at the same time after the dry nitrogen is purged into the anode and the cathode; S3. introducing wet nitrogen into the anode of the fuel cell stack at a third introduction speed, and introducing wet nitrogen into the cathode of the fuel cell stack at a fourth introduction speed, adjusting the anode pressure and the cathode pressure to a second pressure value synchronously, and stopping the introduction of wet nitrogen into the anode and the cathode at the same time after the wet nitrogen purges the anode and the cathode; S4. Turn on the cooling water pump and the circulating water pump, set the water flow rate of the circulating water pump to the first water flow rate, introduce hydrogen into the anode through the constant pressure-hydrogen reflux pump mode, introduce air into the cathode through the stoichiometric ratio mode, set the anode stack pressure and the cathode stack pressure to the first stack pressure, heat the water temperature of the circulating water pump to the first water temperature, set the hydrogen stack humidity to be consistent with the hydrogen stack humidity at the highest point of the polarization curve, set the air stack humidity to be consistent with the air stack humidity at the highest point of the polarization curve, and set the heating tape insulation at the anode and cathode air inlets to the first temperature; S5. Activate the fuel cell stack, the cathode stoichiometric ratio is the stoichiometric ratio corresponding to each current density under the test condition of the polarization curve of the fuel cell stack, and load the fuel cell stack in a constant current mode. Before loading the next current density, run the cathode gas volume and anode reflux pump speed corresponding to the next current density for 1 to 3 minutes, and then adjust the circulating water flow, anode pressure and cathode pressure to the circulating water flow, anode pressure and cathode pressure corresponding to the next current density, until the fuel cell stack is loaded to the highest current density corresponding to the polarization curve; S6. The cathode stoichiometric ratio is reduced, the reduction step is the first reduction step, the first operation time is reduced after multiple steps, and then restored to the normal cathode stoichiometric ratio, wherein the operation time of each step is the second operation time; S7. The cathode stoichiometric ratio is increased by increasing the step size to the first increasing step size, increasing the number of steps to run the third running time, and then returning to the normal cathode stoichiometric ratio, wherein the running time of each step is the fourth running time; S8. After repeating steps S6 and S7 1 to 3 times, activation of the fuel cell stack is completed; S9. The current density of the fuel cell stack is reduced. After the current density of the fuel cell stack is reduced to 0, the introduction of hydrogen and air is stopped and the cooling water pump and the circulating water pump are turned off; S10. Nitrogen is introduced into the hydrogen chamber and the air chamber of the fuel cell stack for purging; Wherein, in the step S2, the first introduction rate is 50-100 splm, the second introduction rate is 70-150 slpm, the first pressure value is 0.5-1.0 bar, and dry nitrogen is purged at the anode and cathode for 3-5 min; In step S3, the third introduction rate is 50-100 splm, the fourth introduction rate is 70-150 slpm, the second pressure value is 0.5-1.0 bar, the relative humidity of the wet nitrogen is 95%, and the wet nitrogen is purged at the anode and cathode for 3-5 minutes.

2. A fuel cell stack activation method according to claim 1, characterized in that: In the step S4, the first water flow rate is 20-80 L / min, the first stack pressure is 0.4-0.6 bar, the first water temperature is 60-80°C, and the first temperature is 60-80°C.

3. A fuel cell stack activation method according to claim 1, characterized in that: In step S6, the first reduction step length is 0.1-0.3, the number of reduction steps is 1-3 steps, the first operation time is 2-5 minutes, and the second operation time is 1-3 minutes.

4. A fuel cell stack activation method according to claim 3, characterized in that: In step S6, the first reduction step size is 0.

2.

5. A fuel cell stack activation method according to claim 1, characterized in that: In step S7, the first increase step length is 0.1-0.3, the increase step number is 1-3 steps, the third operation time is 2-5 minutes, and the fourth operation time is 1-3 minutes.

6. A fuel cell stack activation method according to claim 1, characterized in that: In step S7, the first increasing step is 0.

2.

7. A fuel cell stack activation method according to claim 1, characterized in that: In step S10, wet nitrogen is introduced into the hydrogen cavity and the air cavity of the fuel cell stack at 70-150 slpm for 150-300 seconds, and then dry nitrogen is introduced into the hydrogen cavity and the air cavity of the fuel cell stack at 70-150 slpm for 30-50 seconds.

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