Activation method of proton exchange membrane fuel cell

Abstract

The invention provides an activation method of a proton exchange membrane fuel cell. The activation method comprises the following steps of nitrogen purging, air soaking, high and low potential rapid circulation and cathode starvation. Gas in the cathode and anode pipelines and the cavity is exhausted through nitrogen, and irreversible attenuation of a catalyst caused by a hydrogen-air interface of the anode is prevented; toxic gas on the surface of the anode catalyst is removed through air soaking; through variable current loading, potential rapid circulation is realized, external high humidification is combined, a large amount of water is generated by an electric pile at a low potential to rapidly humidify a proton exchange membrane, the proton transfer resistance is reduced, and impurities on the surface of a cathode catalyst can be removed at a high potential; oxides on the catalytic surface of the cathode are reduced through cathode starvation under high current density, so that the performance of the stack is improved, an efficient and stable three-phase interface transmission channel is formed, and the activation of the fuel cell stack is realized.

Description

Technical Field

[0001] The invention relates to the technical field of fuel cells, in particular to an activation method for a proton exchange membrane fuel cell. Background Art

[0002] A fuel cell is a device that converts the chemical energy of fuel and oxidant directly into electrical energy. Proton exchange membrane fuel cells usually have the advantages of high power density and energy efficiency, good low-temperature starting ability, low pollution, and low noise. The proton exchange membrane fuel cell stack is mainly composed of bipolar plates, membrane electrodes, fixed screws, and end plates. The output power of the stack depends greatly on the output performance of the membrane electrode. The main reasons for the poor performance of the newly prepared membrane electrode are: ① The proton exchange membrane is relatively dry, resulting in too much proton conduction resistance; ② Impurities are introduced into the membrane electrode during the manufacturing process; ③ The catalytic layer is oxidized to form an oxide film covering the catalyst surface; ④ No channels for the transmission of reactants, protons, and electrons are established. Therefore, removing the impurities that poison the catalyst, reducing the oxides of the catalyst, and establishing an efficient three-phase interface can quickly activate the performance of the proton exchange membrane fuel cell.

[0003] The prior art hydrogen fuel cell activation methods are mainly divided into the following categories: the first category is constant current or high current activation, the main mechanism is to generate a large amount of water through high electric density, fully wet the proton exchange membrane and catalyst, so as to reduce the proton conduction resistance, but such methods are time-consuming, the hydrogen consumption is large, and the performance activation effect is not good; the second category is high and low potential cycle, the main mechanism is to reduce the oxide on the catalyst surface by low potential, and oxidize the impurities on the catalytic surface by high potential, and the water generated at the same time fully wets the proton exchange membrane and catalyst to reduce the proton conduction resistance, but such methods are also time-consuming, the hydrogen consumption is large, and long-term operation at low potential will cause the catalyst to mature and agglomerate; the third category is the hydrogen pump method, the main mechanism is that hydrogen is introduced into the anode, the inert gas is introduced into the cathode, and then the external power supply is forced to charge the fuel cell, the hydrogen at the anode is oxidized to release hydrogen ions and electrons, and the hydrogen ions pass through the proton exchange membrane to reduce the oxide in the cathode catalyst, but this method has a weaker activation effect on the catalyst, and the circuit is relatively complex, which is not conducive to control and is easy to damage the stack.

[0004] CN113224353A discloses a rapid activation device for a proton exchange membrane hydrogen fuel cell. This method mainly includes the following steps: ① gas tightness detection of the fuel cell stack; ② alternating cyclic humidification of anode nitrogen and hydrogen; ③ variable current charging; ④ high and low potential cyclic operation; ⑤ cathode gas supply interruption-recovery cycle. This activation method activates the performance of the fuel cell by variable current charging and high and low potential cyclic operation, but it is difficult to accurately control the charging time of the external current by introducing an external power supply, which can easily cause damage to the fuel cell stack. In addition, this method is only suitable for air-cooled fuel cells, and does not take into account the characteristics of different fuel cells, so it is not very applicable.

[0005] In order to meet the needs of mass production of fuel cell stacks and reduce production costs, and to obtain fuel cells with good electrochemical properties, there is an urgent need in this technical field to develop a new fuel cell activation method with short activation time, simple process and low hydrogen consumption.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a method for activating a proton exchange membrane fuel cell, which can meet the needs of mass production of fuel cells and provide a fast and efficient method for activating a fuel cell to reduce the cost of hydrogen consumption.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] In a first aspect, the present invention provides a method for activating a proton exchange membrane fuel cell, the activation method comprising the following steps:

[0010] Nitrogen purge: nitrogen is filled into the anode and cathode of the fuel cell to purge the stack;

[0011] Air soaking: Fill the cathode of the fuel cell with air for purge, and stop nitrogen purge at the anode; after the soaking is completed, fill the anode with humidified fuel and the cathode with humidified oxidant to put the stack in an open circuit state until the lowest single-cell open circuit voltage is not less than 0.95V (for example, it can be 0.96V, 0.97V, 0.98V, 0.99V, 1.0V, etc.), and maintain it for a certain period of time;

[0012] High and low potential cycle: select constant current loading mode, first load current at a loading rate of not less than 45A / s (for example, it can be 45.2A / s, 45.4A / s, 45.6A / s, 45.8A / s, 46A / s, 47A / s, 48A / s, 50A / s, etc.), until the average voltage of the battery stack drops to 0.5-0.6V (for example, it can be 0.5V, 0.52V, 0.54V, 0.56V, 0.58V, 0.6V, etc.), and maintain it for a certain time; then increase the battery stack voltage to the open circuit voltage at a load reduction rate of not less than 45A / s (for example, it can be 45.2A / s, 45.4A / s, 45.6A / s, 45.8A / s, 46A / s, 47A / s, 48A / s, 50A / s, etc.), and maintain it for a certain time;

[0013] Cathode starvation: reduce the cathode stoichiometric ratio to below 0.8 (for example, it can be 0.8, 0.78, 0.76, 0.74, 0.72, 0.7, 0.68, 0.66, 0.64, 0.62, 0.6, 0.58, 0.55, etc.), maintain this stoichiometric ratio for a certain period of time, and then restore it to the normal stoichiometric ratio and maintain it for a certain period of time.

[0014] In the present invention, nitrogen is purged to discharge the gases in the anode and cathode pipelines and the cavity to prevent the occurrence of hydrogen-air interface at the anode, which may cause irreversible attenuation of the catalyst. Then, impurities attached to the surface of the anode catalyst are removed by air immersion. Through rapid potential cycling combined with external high humidification, the stack generates a large amount of water at a low potential to quickly humidify the proton exchange membrane, thereby reducing the proton transfer resistance and removing impurities on the surface of the cathode catalyst at a high potential. Finally, the cathode starvation reduction of the oxide on the cathode catalytic surface at a high electric density greatly improves the performance of the stack, quickly forms an efficient and stable three-phase interface transmission channel, and realizes rapid activation of the fuel cell stack.

[0015] Preferably, the nitrogen purge also includes a stack air tightness test: detecting whether the air tightness of the fuel cell meets the air tightness standard; if so, proceeding to the next step of nitrogen purge; if not, re-repairing the stack.

[0016] Preferably, the method for testing the gas tightness of the fuel cell stack is: adopting 5.4 gas leakage test and 5.5 blowby test in "GBT 20042.2-2023 Proton Exchange Membrane Fuel Cell Part 2 General Technical Conditions for Battery Stacks"; wherein, the maximum working pressure in the gas leakage test is 180kPa; the maximum working pressure difference in the blowby test is 50kPa, and the maximum operating pressure is 180kPa.

[0017] Preferably, the airtightness standards are: battery stack blowby rate standard <1mL / min / cell; battery stack leakage rate standard <21mL / min.

[0018] Preferably, in the nitrogen purging step, the flow rates of nitrogen filled into the anode and cathode of the fuel cell for stack purging are each independently 0.8 to 1.2 sccm / cell sccm, for example, 0.8 sccm / cell sccm, 0.9 sccm / cell sccm, 1.0 sccm / cell sccm, 1.1 sccm / cell sccm, 1.2 sccm / cell sccm, etc., and the stack purging time is each independently 15 to 20 s, for example, 15 s, 16 s, 17 s, 18 s, 19 s, 20 s, etc.

[0019] Preferably, the cathode of the fuel cell is purged with air, and the specific steps of purging the anode with maintenance gas are:

[0020] (a) switching the nitrogen at the cathode to air, and making the cathode inlet pressure 20-40 kPa higher than the anode inlet pressure (for example, 20 kPa, 22 kPa, 24 kPa, 26 kPa, 28 kPa, 30 kPa, 32 kPa, 34 kPa, 36 kPa, 38 kPa, 40 kPa, etc.), and maintaining nitrogen purge at the anode for 20-40 s (for example, 20 s, 22 s, 24 s, 26 s, 28 s, 30 s, 32 s, 34 s, 36 s, 38 s, 40 s, etc.);

[0021] (b) turning off the nitrogen purge at the anode and allowing the cathode to be continuously filled with air for 3 to 5 minutes (e.g., 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, etc.);

[0022] (c) Restore the nitrogen purge at the anode and make the anode inlet pressure 10-20 kPa higher than the cathode inlet pressure (for example, it can be 10 kPa, 12 kPa, 14 kPa, 16 kPa, 18 kPa, 20 kPa, etc.), and maintain air purge at the cathode for 10-30 s (for example, it can be 10 s, 15 s, 20 s, 25 s, 30 s, etc.).

[0023] Preferably, in the air immersion step, the minimum single-cell open-circuit voltage is not less than 0.95V, and the maintenance time is more than 10s (for example, it can be 10s, 12s, 14s, 16s, 18s, 20s, 22s, 24s, 26s, 28s, 30s, etc.), preferably 10 to 30s.

[0024] Preferably, the fuel is hydrogen.

[0025] Preferably, the oxidant is air and / or oxygen.

[0026] Preferably, the humidity of the humidified fuel and the humidified oxidant is above 80% (for example, it may be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 100%, etc.).

[0027] Preferably, the filling flow rate of the humidified fuel is 3 to 5 nlpm / cell, for example, it can be 3nlpm / cell, 3.5nlpm / cell, 4nlpm / cell, 4.5nlpm / cell, 5nlpm / cell, etc., and the filling time is 10 to 30s, for example, it can be 10s, 12s, 14s, 16s, 18s, 20s, 22s, 24s, 26s, 28s, 30s, etc.

[0028] Preferably, the charging flow rate of the humidified oxidant is 5 to 10 nlpm / cell, for example, it can be 5 nlpm / cell, 6 nlpm / cell, 7 nlpm / cell, 8 nlpm / cell, 9 nlpm / cell, 10 nlpm / cell, etc., and the charging time is 10 to 30 s, for example, it can be 10s, 12s, 14s, 16s, 18s, 20s, 22s, 24s, 26s, 28s, 30s, etc.

[0029] Preferably, the high and low potential cycle step needs to be repeated for more than 3 times (for example, 3 times, 4 times, 5 times, 6 times, etc.), preferably 3 to 4 times.

[0030] Preferably, the high and low potential cycle step also includes supplying anode and cathode flows to the stack according to a stoichiometric ratio corresponding to the current.

[0031] Preferably, the metering ratio is 1.5-2 (for example, it can be 1.5, 1.6, 1.7, 1.8, 1.9, 2).

[0032] Preferably, the high and low potential cycle step also includes increasing the anode and cathode inlet pressures of the fuel cell stack; wherein the cathode inlet pressure is 250-280 kPa (for example, it may be 250 kPa, 255 kPa, 260 kPa, 265 kPa, 270 kPa, 275 kPa, 280 kPa, etc.), and the anode inlet pressure is maintained 10-20 kPa higher than the cathode inlet pressure (for example, it may be 10 kPa, 12 kPa, 14 kPa, 16 kPa, 18 kPa, 20 kPa, etc.).

[0033] Preferably, in the high-low potential cycle step, after the voltage drops to 0.5-0.6V, it is maintained at this constant current for 120-180s (for example, it can be 120s, 130s, 140s, 150s, 160s, 170s, 180s, etc.).

[0034] Preferably, in the high-low potential cycle step, the voltage is increased to the open circuit voltage and then maintained for 10 to 20 seconds (for example, 10 seconds, 12 seconds, 14 seconds, 16 seconds, 18 seconds, 20 seconds, etc.).

[0035] Preferably, the cathode starvation step needs to be repeated for more than 5 times (for example, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, etc.), preferably 5 to 8 times.

[0036] Preferably, in the cathode starvation step, the current density is 1.0 to 1.2 A / cm 2 (For example, it can be 1.0A / cm 2 , 1.02A / cm 2 , 1.04A / cm2 , 1.06A / cm 2 , 1.08A / cm 2 , 1.1A / cm 2 , 1.12A / cm 2 , 1.14A / cm 2 , 1.16A / cm 2 , 1.18A / cm 2 , 1.2A / cm 2 wait).

[0037] Preferably, the cathode stoichiometry ratio is 0.6 to 0.8 (eg, 0.6, 0.65, 0.7, 0.75, 0.8, etc.).

[0038] Preferably, after the cathode stoichiometric ratio is reduced to 0.6-0.8, it needs to be maintained for 6-10 seconds (for example, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, etc.).

[0039] Preferably, after the cathode stoichiometric ratio is restored to the normal stoichiometric ratio, it needs to be maintained for 6 to 10 seconds (for example, 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, etc.).

[0040] Preferably, the cathode starvation step further comprises determining that activation is complete:

[0041] The activation is completed by cycling the high and low potential cycles and the cathode starvation steps until the average single-chip voltage under constant current no longer increases or the voltage increase value is no greater than the test error value.

[0042] Preferably, the number of cycles is 3 or more, for example, 3, 4, 5, 6, 7, 8, etc., preferably 3 to 5 times.

[0043] In the present invention, the number of cycles here refers to the total number of cycles after high and low potential cycles are completed, cathode starvation cycles are completed, and then large mixed cycles are performed.

[0044] Preferably, the error value is 2mV.

[0045] Preferably, the step of determining that the activation is completed further includes shutting down and purging:

[0046] Supply hydrogen to the anode and nitrogen to the cathode until the average voltage is less than 0.2 V (e.g., 0.19 V, 0.18 V, 0.17 V, 0.16 V, 0.15 V, etc.);

[0047] Cut off the load, switch the anode to nitrogen, and maintain nitrogen purging at the cathode until the HFR value of the battery stack is greater than 0.2mΩ / cell (for example, it can be 0.21mΩ / cell, 0.22mΩ / cell, 0.25mΩ / cell, 0.28mΩ / cell, 0.3mΩ / cell, etc.), and stop purging.

[0048] Preferably, the current density of the shutdown purge is 0.05-0.1 A / cm 2 (For example, it can be 0.05A / cm 2 , 0.06A / cm 2 , 0.08A / cm 2 , 0.09A / cm 2 , 0.1A / cm 2 wait).

[0049] Preferably, the stack purge time is 2 to 3 minutes (for example, 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, 3 minutes, etc.).

[0050] In the present invention, the stack purge time here refers to: the time during which the anode and cathode maintain nitrogen purge, the purpose of which is to reduce the voltage of the stack and remove the accumulated water inside the stack.

[0051] As a preferred technical solution of the present invention, the activation method of the proton exchange membrane fuel cell specifically comprises the following steps (such as Figure 1 shown):

[0052] S1. Stack air tightness test: Check whether the fuel cell air tightness meets the air tightness standard; if so, proceed to the next step of nitrogen purge; if not, repair the stack;

[0053] S2, nitrogen purge: nitrogen is charged into the anode and cathode of the fuel cell to purge the stack;

[0054] S3, air soaking: Fill the cathode of the fuel cell with air for purge, and stop nitrogen purge at the anode; after soaking, fill the anode with humidified fuel and the cathode with humidified oxidant to put the stack in an open circuit state until the lowest single-cell open circuit voltage is not less than 0.95V and maintained for a certain period of time; if it is not less than 0.95V, proceed to the next step of high and low potential cycle; if the low single-cell open circuit voltage is below 0.95V, perform stack repair;

[0055] S4, high and low potential cycle: select constant current loading mode, first load current at a loading rate of not less than 45A / s, until the average voltage of the battery stack drops to 0.5-0.6V, and maintain it for a certain time; then increase the battery stack voltage to the open circuit voltage at a load reduction rate of not less than 45A / s, and maintain it for a certain time;

[0056] S5, cathode starvation: reduce the cathode stoichiometric ratio to below 0.8, maintain this stoichiometric ratio for a certain period of time, then restore to the normal stoichiometric ratio and maintain it for a certain period of time;

[0057] S6, judging that activation is completed: by cycling the steps of high and low potential cycling and cathode starvation, until the average single-chip voltage under constant current no longer increases or the voltage increase value is not greater than the test error value; if so, activation is completed, if not, returning to S4 and re-cycling the high and low potential;

[0058] S7, shutdown and purge: supply hydrogen to the anode and nitrogen to the cathode until the average voltage is less than 0.2V; cut off the load, switch the anode to nitrogen, and maintain nitrogen purge at the cathode until the HFR value of the battery stack is greater than 0.2mΩ / cell, then stop purge.

[0059] The present invention firstly tests the gas tightness of the stack by maintaining pressure on the test bench; then uses nitrogen purge strategy to discharge the gas in the anode and cathode pipelines and the cavity with nitrogen to prevent the irreversible attenuation of the catalyst caused by the hydrogen-air interface at the anode; then adopts air immersion method to remove the toxic gases (CO, NO 2 、SO 2 ) removal; rapid potential cycling is achieved through variable current loading, and combined with external high humidification, the stack generates a large amount of water at low potential to quickly humidify the proton exchange membrane, reducing the proton transmission resistance, and at the same time, impurities on the cathode catalyst surface can be removed at high potential; finally, the cathode starvation reduction of the oxide on the cathode catalytic surface at high current density greatly improves the performance of the stack, quickly forms an efficient and stable three-phase interface transmission channel, and realizes the rapid activation of the fuel cell stack. Therefore, the present invention fully takes into account the different characteristics of the fuel cell membrane electrode catalyst, and the method of the present invention can fully activate the performance of the fuel cell in a very short time, greatly shorten the activation time, and improve the activation efficiency.

[0060] Furthermore, as the most preferred technical solution of the present invention, the activation method of the proton exchange membrane fuel cell specifically comprises the following steps:

[0061] S1. Stack air tightness test: Check whether the fuel cell air tightness meets the air tightness standard; if yes, proceed to the next step; if no, repair the stack;

[0062] S2, nitrogen purge: nitrogen is charged into the anode and cathode of the fuel cell to purge the stack;

[0063] S3, air soaking: switch the nitrogen at the cathode to air, maintain the cathode inlet pressure 20-40 kPa higher than the anode inlet pressure, and continue to purge the anode with nitrogen for 20-40 seconds; then turn off the anode gas purge, and continue to fill the cathode with air for 3-5 minutes; then resume nitrogen purge at the anode, and restore the anode inlet pressure to 10-20 kPa higher than the cathode inlet pressure, and maintain air purge at the cathode for 10-30 seconds; finally, fill the anode with humidified fuel and the cathode with humidified oxidant, so that the stack is in an open circuit state until the lowest single-cell open circuit voltage is not less than 0.95V, and maintain for 10-30 seconds;

[0064] S4, high and low potential cycle: turn on the load, select the constant current loading mode, supply the anode and cathode flow of the stack according to the metering ratio corresponding to the current, and at the same time increase the anode and cathode inlet pressure of the stack. The cathode inlet pressure is 250-280kPa, and the anode inlet pressure is maintained 10-20kPa higher than the cathode inlet pressure. Load the current quickly at a loading rate of not less than 45A / s until the average voltage of the stack reaches 0.5-0.6V, maintain it at this constant current for 120-180s, and then maintain the same load reduction rate to reduce the stack voltage to the open circuit voltage and maintain it for 10-20s. Repeat this step 3-4 times and proceed to the next step;

[0065] S5, cathode starvation: 1.0~1.2A / cm 2 Under the current density, the cathode stoichiometric ratio is reduced from the normal stoichiometric ratio to 0.6-0.8, and this stoichiometric ratio is maintained for 6-10 seconds, and then restored to the normal stoichiometric ratio for 6-10 seconds. This step is repeated 5-8 times before proceeding to the next step;

[0066] S6, judging that activation is completed: by cycling the high and low potential cycles of step S4 and cathode starvation of step S5 for several times, until the average single-chip voltage under constant current no longer increases or the increase value is not greater than the test error value, that is, activation is completed;

[0067] S7, shutdown and purge: set the current density to 0.05~0.1A / cm 2 , hydrogen is supplied to the anode and nitrogen is supplied to the cathode until the average voltage is less than 0.2V, the load is cut off and the anode is switched to nitrogen, and the cathode is purged with nitrogen until the HFR value of the stack is greater than 0.2mΩ / cell, and the purging is stopped.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] (1) The present invention discharges the gas in the anode and cathode pipelines and the cavity by nitrogen purge to prevent the occurrence of hydrogen-air interface at the anode, which causes irreversible attenuation of the catalyst; then, impurities attached to the surface of the anode catalyst are removed by air immersion;

[0070] (2) The present invention uses rapid potential cycling combined with external high humidification to generate a large amount of water at a low potential to quickly humidify the proton exchange membrane, thereby reducing the proton transfer resistance and removing impurities on the cathode catalyst surface at a high potential.

[0071] (3) The present invention finally reduces the oxide on the cathode catalytic surface by cathode starvation under high electric density, thereby greatly improving the performance of the fuel cell stack, quickly forming an efficient and stable three-phase interface transmission channel, and realizing rapid activation of the fuel cell stack;

[0072] (4) The present invention fully considers the characteristics of different catalysts of the membrane electrode of the fuel cell. The method of the present invention can be applied to almost all the membrane electrodes of the fuel cell, and has a very wide range of applications;

[0073] (5) The present invention can fully activate the performance of the fuel cell in a very short time. The entire activation process takes about 45 to 60 minutes to complete, greatly reducing hydrogen consumption and improving activation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0075] Figure 1 The figure is a schematic diagram of the process flow of the activation method of the proton exchange membrane fuel cell of the present invention.

[0076] Figure 2 The performance curve comparison diagram of the unactivated, conventionally activated and rapidly activated fuel cell stacks provided in Example 1 is shown.

[0077] Figure 3 This is a performance curve diagram of Example 2 that performs an air soaking step and Comparative Example 1 that does not perform an air soaking step.

[0078] Figure 4 It is a performance curve diagram of Example 4 performing high and low potential rapid cycling steps and Comparative Example 2 not performing high and low potential rapid cycling steps.

[0079] Figure 5 It is a performance curve diagram of Example 3 performing the cathode starvation step at a high current density and Comparative Example 3 performing the cathode starvation step at a low current density. DETAILED DESCRIPTION

[0080] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0081] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0082] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0083] Example 1

[0084] The embodiment of the present invention provides a general method for rapid activation of a proton exchange membrane fuel cell, the method comprising the following steps:

[0085] S1. Stack air tightness test: Check whether the fuel cell air tightness meets the air tightness standard; if yes, proceed to the next step; if no, repair the stack;

[0086] S2, nitrogen purge: nitrogen is charged into the anode and cathode of the fuel cell to purge the stack;

[0087] S3, air soaking: switch the nitrogen at the cathode to air, maintain the cathode inlet pressure 20kPa higher than the anode inlet pressure, and continue to purge the anode with nitrogen for 20s; then turn off the anode gas purge, and continue to fill the cathode with air for 3min; then resume nitrogen purge at the anode, and restore the anode inlet pressure to 10kPa higher than the cathode inlet pressure, and maintain air purge at the cathode for 10s; finally, fill the anode with fuel with 100% humidity, and fill the cathode with oxidant with 100% humidity, so that the stack is in an open circuit state until the lowest single-cell open circuit voltage reaches 0.95V, which is maintained for 10s;

[0088] S4, high and low potential cycle: turn on the load, select the constant current loading mode, supply the anode and cathode flow of the stack according to the metering ratio corresponding to the current, and at the same time increase the anode and cathode inlet pressure of the stack. The cathode inlet pressure is 250kPa, and the anode inlet pressure is maintained 10kPa higher than the cathode inlet pressure. Load the current quickly at a loading rate of 45A / s until the average voltage of the stack reaches 0.5V. Maintain this constant current for 120s, then maintain the same load reduction rate to reduce the stack voltage to the open circuit voltage and maintain it for 10s. Repeat this step 3 times and proceed to the next step;

[0089] S5, cathode starvation: at 1.0A / cm 2 Under the current density, the cathode stoichiometric ratio is reduced from the normal stoichiometric ratio to 0.6, and after maintaining this stoichiometric ratio for 6 seconds, it is restored to the normal stoichiometric ratio and maintained for 6 seconds. This step is repeated 5 times before proceeding to the next step;

[0090] S6, judging that activation is completed: by cycling the high and low potential cycles of step S4 and cathode starvation of step S5 for several times, until the average single-chip voltage under constant current no longer increases or the increase value is no more than 2 mV, the activation is completed;

[0091] S7, shutdown and purge: set the current density to 0.05A / cm 2 , hydrogen is supplied to the anode and nitrogen is supplied to the cathode until the average voltage is equal to 0.2V, the load is cut off and the anode is switched to nitrogen, and the cathode is purged with nitrogen until the HFR value of the stack is equal to 0.2mΩ / cell, and the purging is stopped.

[0092] Example 2

[0093] S1. Stack air tightness test: Check whether the fuel cell air tightness meets the air tightness standard; if yes, proceed to the next step; if no, repair the stack;

[0094] S2, nitrogen purge: nitrogen is charged into the anode and cathode of the fuel cell to purge the stack;

[0095] S3, air soaking: switch the nitrogen at the cathode to air, maintain the cathode inlet pressure 30kPa higher than the anode inlet pressure, and continue to purge the anode with nitrogen for 30s; then turn off the anode gas purge, and continue to fill the cathode with air for 4min; then resume nitrogen purge at the anode, and restore the anode inlet pressure to 20kPa higher than the cathode inlet pressure, and maintain air purge at the cathode for 20s; finally, fill the anode with fuel with a humidity of 90%, and fill the cathode with oxidant with a humidity of 90%, so that the stack is in an open circuit state until the lowest single-cell open circuit voltage reaches 0.96V, which is maintained for 20s;

[0096] S4, high and low potential cycle: turn on the load, select the constant current loading mode, supply the anode and cathode flow of the stack according to the metering ratio corresponding to the current, and at the same time increase the anode and cathode inlet pressure of the stack. The cathode inlet pressure is 260kPaA, and the anode inlet pressure is maintained 20kPa higher than the cathode inlet pressure. Load the current quickly at a loading rate of 50A / s until the average voltage of the stack reaches 0.55V, maintain it at this constant current for 150s, and then maintain the same load reduction rate to reduce the stack voltage to the open circuit voltage for 20s. Repeat this step 4 times and proceed to the next step;

[0097] S5, cathode starvation: at 1.1A / cm 2 Under the current density, the cathode stoichiometric ratio is reduced from the normal stoichiometric ratio to 0.7, maintained at this stoichiometric ratio for 8 seconds, and then restored to the normal stoichiometric ratio for 8 seconds. This step is repeated 6 times before proceeding to the next step;

[0098] S6, judging that activation is completed: by cycling the high and low potential cycles of step S4 and cathode starvation of step S5 for several times, until the average single-chip voltage under constant current no longer increases or the increase value is no more than 2 mV, the activation is completed;

[0099] S7, shutdown and purge: set the current density to 0.08A / cm 2 , hydrogen is supplied to the anode and nitrogen is supplied to the cathode until the average voltage is equal to 0.25V, the load is cut off and the anode is switched to nitrogen, and the cathode is purged with nitrogen until the HFR value of the stack is equal to 0.2mΩ / cell, and the purging is stopped.

[0100] Example 3

[0101] S1. Stack air tightness test: Check whether the fuel cell air tightness meets the air tightness standard; if yes, proceed to the next step; if no, repair the stack;

[0102] S2, nitrogen purge: nitrogen is charged into the anode and cathode of the fuel cell to purge the stack;

[0103] S3, air soaking: switch the nitrogen at the cathode to air, maintain the cathode inlet pressure 40kPa higher than the anode inlet pressure, and continue to purge the anode with nitrogen for 20s; then turn off the anode gas purge, and continue to fill the cathode with air for 5min; then resume nitrogen purge at the anode, and restore the anode inlet pressure to 10kPa higher than the cathode inlet pressure, and maintain air purge at the cathode for 10s; finally, fill the anode with fuel with a humidity of 80%, and fill the cathode with oxidant with a humidity of 80%, so that the stack is in an open circuit state until the lowest single-cell open circuit voltage reaches 0.95V, which is maintained for 10s;

[0104] S4, high and low potential cycle: turn on the load, select the constant current loading mode, supply the anode and cathode flow of the stack according to the metering ratio corresponding to the current, and at the same time increase the anode and cathode inlet pressure of the stack. The cathode inlet pressure is 270kPa, and the anode inlet pressure is maintained 10kPa higher than the cathode inlet pressure. Load the current quickly at a loading rate of 55A / s until the average voltage of the stack reaches 0.6V. Maintain this constant current for 180s, then maintain the same load reduction rate to reduce the stack voltage to the open circuit voltage and maintain it for 10s. Repeat this step 3 times and proceed to the next step;

[0105] S5, cathode starvation: at 1.2A / cm 2 Under the current density, the cathode stoichiometric ratio is reduced from the normal stoichiometric ratio to 0.8, and then maintained at this stoichiometric ratio for 10 seconds and then restored to the normal stoichiometric ratio for 10 seconds. This step is repeated 8 times before proceeding to the next step;

[0106] S6, judging that activation is completed: by cycling the high and low potential cycles of step S4 and cathode starvation of step S5 for several times, until the average single-chip voltage under constant current no longer increases or the increase value is no more than 2 mV, the activation is completed;

[0107] S7, shutdown and purge: set the current density to 0.1A / cm 2 , hydrogen is supplied to the anode and nitrogen is supplied to the cathode until the average voltage is equal to 0.2V, the load is cut off and the anode is switched to nitrogen, and the cathode is purged with nitrogen until the HFR value of the stack is equal to 0.2mΩ / cell, and the purging is stopped.

[0108] Example 4

[0109] S1. Stack air tightness test: Check whether the fuel cell air tightness meets the air tightness standard; if yes, proceed to the next step; if no, repair the stack;

[0110] S2, nitrogen purge: nitrogen is charged into the anode and cathode of the fuel cell to purge the stack;

[0111] S3, air soaking: switch the nitrogen at the cathode to air, maintain the cathode inlet pressure 20kPa higher than the anode inlet pressure, and continue to purge the anode with nitrogen for 10s; then turn off the anode gas purge, and continue to fill the cathode with air for 3min; then resume nitrogen purge at the anode, and restore the anode inlet pressure to 20kPa higher than the cathode inlet pressure, and maintain air purge at the cathode for 20s; finally, fill the anode with fuel with a humidity of 80%, and fill the cathode with oxidant with a humidity of 100%, so that the stack is in an open circuit state until the lowest single-cell open circuit voltage reaches 0.95V, which is maintained for 20s;

[0112] S4, high and low potential cycle: turn on the load, select the constant current loading mode, supply the anode and cathode flow of the stack according to the metering ratio corresponding to the current, and at the same time increase the anode and cathode inlet pressure of the stack. The cathode inlet pressure is 280kPa, and the anode inlet pressure is maintained 20kPa higher than the cathode inlet pressure. Load the current quickly at a loading rate of 60A / s until the average voltage of the stack reaches 0.56V. Maintain this constant current for 120s, then maintain the same load reduction rate to reduce the stack voltage to the open circuit voltage and maintain it for 20s. Repeat this step 4 times and proceed to the next step;

[0113] S5, cathode starvation: at 1.05A / cm 2 Under the current density, the cathode stoichiometric ratio is reduced from the normal stoichiometric ratio to 0.8, maintained at this stoichiometric ratio for 6 seconds, and then restored to the normal stoichiometric ratio for 8 seconds. This step is repeated 6 times before proceeding to the next step;

[0114] S6, judging that activation is completed: by cycling the high and low potential cycles of step S4 and cathode starvation of step S5 for several times, until the average single-chip voltage under constant current no longer increases or the increase value is no more than 2 mV, the activation is completed;

[0115] S7, shutdown and purge: set the current density to 0.05A / cm 2 , hydrogen is supplied to the anode and nitrogen is supplied to the cathode until the average voltage is equal to 0.2V, the load is cut off and the anode is switched to nitrogen, and the cathode is purged with nitrogen until the HFR value of the stack is equal to 0.2mΩ / cell, and the purging is stopped.

[0116] Example 5

[0117] S1. Stack air tightness test: Check whether the fuel cell air tightness meets the air tightness standard; if yes, proceed to the next step; if no, repair the stack;

[0118] S2, nitrogen purge: nitrogen is charged into the anode and cathode of the fuel cell to purge the stack;

[0119] S3, air soaking: switch the nitrogen at the cathode to air, maintain the cathode inlet pressure 40kPa higher than the anode inlet pressure, and continue to purge the anode with nitrogen for 20s; then turn off the anode gas purge, and continue to fill the cathode with air for 5min; then resume nitrogen purge at the anode, and restore the anode inlet pressure to 10kPa higher than the cathode inlet pressure, and maintain air purge at the cathode for 10s; finally, fill the anode with fuel with a humidity of 90%, and fill the cathode with oxidant with a humidity of 100%, so that the stack is in an open circuit state until the lowest single-cell open circuit voltage reaches 0.97V, which is maintained for 10s;

[0120] S4, high and low potential cycle: turn on the load, select the constant current loading mode, supply the anode and cathode flow of the stack according to the metering ratio corresponding to the current, and at the same time increase the anode and cathode inlet pressure of the stack. The cathode inlet pressure is 255kPa, and the anode inlet pressure is maintained 10kPa higher than the cathode inlet pressure. Load the current quickly at a loading rate of 54A / s until the average voltage of the stack reaches 0.52V. Maintain this constant current for 130s, then maintain the same load reduction rate to reduce the stack voltage to the open circuit voltage and maintain it for 10s. Repeat this step 3 times and proceed to the next step;

[0121] S5, cathode starvation: at 1.0A / cm 2 Under the current density, the cathode stoichiometric ratio is reduced from the normal stoichiometric ratio to 0.75, maintained at this stoichiometric ratio for 8 seconds, and then restored to the normal stoichiometric ratio for 6 seconds. This step is repeated 7 times before proceeding to the next step;

[0122] S6, judging that activation is completed: by cycling the high and low potential cycles of step S4 and cathode starvation of step S5 for several times, until the average single-chip voltage under constant current no longer increases or the increase value is no more than 2 mV, the activation is completed;

[0123] S7, shutdown and purge: set the current density to 0.06A / cm 2 , hydrogen is supplied to the anode and nitrogen is supplied to the cathode until the average voltage is equal to 0.25V, the load is cut off and the anode is switched to nitrogen, and the cathode is purged with nitrogen until the HFR value of the stack is equal to 0.2mΩ / cell, and the purging is stopped.

[0124] like Figure 2 As shown, from the comparison of the unactivated battery stack, conventional activation and the rapid activation provided by the present invention, it can be seen that the method of the present invention greatly improves the performance of the battery stack, quickly forms an efficient and stable three-phase interface transmission channel, and realizes the rapid activation of the fuel cell stack.

[0125] Comparative Example 1

[0126] This comparative example provides a proton exchange membrane fuel cell activation method, which differs from Example 2 only in that the cathode in S3 is still purged with nitrogen instead of being switched to air.

[0127] like Figure 3 As shown, the present invention discharges the gas in the anode and cathode pipelines and the cavity by nitrogen purge to prevent the occurrence of hydrogen-air interface at the anode and cause irreversible attenuation of the catalyst; then the impurities attached to the surface of the anode catalyst are removed by air immersion, which is beneficial to the subsequent rapid potential cycle; if air immersion is not performed and nitrogen purging is continued, impurities are still attached to the surface of the anode catalyst, and the activation efficiency is low.

[0128] Comparative Example 2

[0129] This comparative example provides a proton exchange membrane fuel cell activation method, which differs from Example 4 only in that only high potential cycles are performed instead of high and low potential rapid cycles.

[0130] like Figure 4 As shown, through rapid potential cycling combined with external high humidification, the fuel cell stack generates a large amount of water at low potential to quickly humidify the proton exchange membrane, reducing the proton transfer resistance, while impurities on the cathode catalyst surface can be removed at high potential.

[0131] Comparative Example 3

[0132] This comparative example provides a proton exchange membrane fuel cell activation method. The method is different from Example 3 only in that cathode starvation is performed at a low electrical density, and the low electrical density is 0.2 A / cm 2 .

[0133] like Figure 5 As shown, by reducing the oxides on the cathode catalytic surface by cathode starvation at high current density, the performance of the fuel cell stack is greatly improved, an efficient and stable three-phase interface transmission channel is quickly formed, and rapid activation of the fuel cell stack is achieved.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for activating a proton exchange membrane fuel cell, characterized in that: The activation method comprises the following steps: Nitrogen purge: nitrogen is filled into the anode and cathode of the fuel cell to purge the stack; Air soaking: Fill air into the cathode of the fuel cell for purge, and stop nitrogen purge at the anode; after the soaking is completed, fill the anode with humidified fuel and the cathode with humidified oxidant to put the stack in an open circuit state until the lowest single-cell open circuit voltage is not less than 0.95V and is maintained for a certain period of time; High and low potential cycle: Select the constant current loading mode, first load the current at a loading rate of not less than 45A / s until the average voltage of the battery stack drops to 0.5-0.6V and maintain it for a certain period of time; then increase the battery stack voltage to the open circuit voltage at a load reduction rate of not less than 45A / s and maintain it for a certain period of time; Cathode starvation: Reduce the cathode stoichiometric ratio to below 0.8, maintain this stoichiometric ratio for a certain period of time, then restore it to the normal stoichiometric ratio and maintain it for a certain period of time.

2. The method for activating a proton exchange membrane fuel cell according to claim 1, characterized in that: Before the nitrogen purge, the stack air tightness test is also included: check whether the air tightness of the fuel cell meets the air tightness standard; if so, proceed to the next step of nitrogen purge; if not, rework the stack; Preferably, the method for testing the gas tightness of the fuel cell stack is: adopting 5.4 gas leakage test and 5.5 blowby test in "GBT 20042.2-2023 Proton Exchange Membrane Fuel Cell Part 2 General Technical Conditions for Fuel Cell Stacks"; wherein, the maximum working pressure in the gas leakage test is 180kPa; the maximum working pressure difference in the blowby test is 50kPa, and the maximum operating pressure is 180kPa; Preferably, the airtightness standards are: battery stack blowby rate standard <1mL / min / cell; battery stack leakage rate standard <21mL / min.

3. The method for activating a proton exchange membrane fuel cell according to claim 1, characterized in that: In the nitrogen purging step, the flow rates of nitrogen injected into the anode and cathode of the fuel cell for stack purging are independently 0.8 to 1.2 sccm / cellsccm, and the stack purging time is independently 15 to 20 seconds.

4. The method for activating a proton exchange membrane fuel cell according to claim 1, characterized in that: The specific steps of the air soaking are: (a) Switch the nitrogen gas at the cathode to air, and make the cathode inlet pressure 20-40 kPa higher than the anode inlet pressure. Maintain nitrogen purge at the anode for 20-40 seconds. (b) Turn off the nitrogen purge at the anode and allow the cathode to continue to be filled with air for 3 to 5 minutes; (c) Restore the nitrogen purge at the anode and make the anode inlet pressure 10 to 20 kPa higher than the cathode inlet pressure. Maintain air purge at the cathode for 10 to 30 seconds.

5. The method for activating a proton exchange membrane fuel cell according to claim 1, characterized in that: In the air soaking step, the lowest single-cell open circuit voltage is not less than 0.95V, and the maintenance time is more than 10 seconds, preferably 10 to 30 seconds; Preferably, the fuel is hydrogen; Preferably, the oxidant is air and / or oxygen; Preferably, the humidity of the humidified fuel and the humidified oxidant is above 80%; Preferably, the humidified fuel has a charging flow rate of 3 to 5 nlpm / cell and a charging time of 10 to 30 s; Preferably, the charging flow rate of the humidified oxidant is 5 to 10 nlpm / cell, and the charging time is 10 to 30 s.

6. The method for activating a proton exchange membrane fuel cell according to claim 1, characterized in that: The high and low potential cycle step needs to be repeated more than 3 times, preferably 3 to 4 times; Preferably, the high and low potential cycle step further includes supplying anode and cathode flows of the stack according to a stoichiometric ratio corresponding to the current; Preferably, the metering ratio is 1.5 to 2; Preferably, the high and low potential cycle step further includes increasing the anode and cathode inlet pressures of the stack; wherein the cathode inlet pressure is 250-280 kPa, and the anode inlet pressure is maintained 10-20 kPa higher than the cathode inlet pressure; Preferably, in the high-low potential cycle step, after the voltage drops to 0.5-0.6V, it is maintained at this constant current for 120-180s; Preferably, in the high-low potential cycle step, the open circuit voltage is increased and then maintained for 10 to 20 seconds.

7. The method for activating a proton exchange membrane fuel cell according to claim 1, characterized in that: The cathode starvation step needs to be repeated for more than 5 times, preferably 5 to 8 times; Preferably, in the cathode starvation step, the current density is 1.0 to 1.2 A / cm 2 ; Preferably, the cathode stoichiometry is 0.6 to 0.8; Preferably, after the cathode stoichiometric ratio is reduced to 0.6 to 0.8, it needs to be maintained for 6 to 10 seconds; Preferably, the cathode stoichiometric ratio needs to be maintained for 6 to 10 seconds after it returns to the normal stoichiometric ratio.

8. The method for activating a proton exchange membrane fuel cell according to claim 1, characterized in that: The cathode starvation step further includes determining that activation is complete: The activation is completed by cycling the high and low potential cycles and the cathode starvation step until the average single-chip voltage under constant current no longer increases or the voltage increase value is not greater than the test error value; Preferably, the number of cycles is 3 or more, preferably 3 to 5 times; Preferably, the error value is 2mV.

9. The method for activating a proton exchange membrane fuel cell according to claim 8, characterized in that: The step of determining that the activation is completed also includes shutting down for purging: Supply hydrogen to the anode and nitrogen to the cathode until the average voltage is less than 0.2V; Cut off the load, switch the anode to nitrogen, and maintain nitrogen purging at the cathode until the HFR value of the battery stack is greater than 0.2mΩ / cell, then stop purging.

10. The method for activating a proton exchange membrane fuel cell according to claim 9, characterized in that: The current density of the shutdown purge is 0.05-0.1A / cm 2 ; Preferably, the stack purge time is 2 to 3 minutes.

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