A method of activating a proton exchange membrane fuel cell

Abstract

The application provides an activation method of a proton exchange membrane fuel cell. The activation method comprises the following steps: nitrogen purging, air soaking, high-low potential rapid circulation, cathode starvation. The application discharges the gas in the anode and cathode pipelines and cavities through nitrogen, prevents the hydrogen-air interface of the anode from causing irreversible attenuation of the catalyst, removes the toxic gas on the surface of the anode catalyst through air soaking, realizes potential rapid circulation through variable current loading, combines external high humidification, generates a large amount of water at low potential to rapidly humidify the proton exchange membrane, reduces the proton transmission resistance, and removes the impurities on the surface of the cathode catalyst at high potential, reduces the proton transmission resistance, and removes the impurities on the surface of the cathode catalyst at high potential. Through cathode starvation at high current density, the oxide on the surface of the cathode catalyst is reduced, the performance of the stack is improved, a high-efficiency stable three-phase interface transmission channel is formed, and the activation of the fuel cell stack is realized.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to an activation method for a proton exchange membrane fuel cell. Background Technology

[0002] A fuel cell is a device that directly converts the chemical energy of fuel and oxidant into electrical energy. Proton exchange membrane fuel cells (PEMFCs) typically possess advantages such as high power density and energy efficiency, good low-temperature start-up capability, and low pollution and noise. A PEMFC stack mainly consists of bipolar plates, membrane electrode assemblies (MEAs), and fixed screws and end plates. The stack's output power largely depends on the performance of the MEAs. The main reasons for poor performance of newly fabricated MEAs are: ① the proton exchange membrane is too dry, resulting in excessive proton conduction resistance; ② impurities are introduced into the MEAs during manufacturing; ③ the catalyst layer is oxidized, forming an oxide film covering the catalyst surface; ④ no channels are established for the transport of reactants, protons, and electrons. Therefore, removing poisoned impurities from the catalyst, reducing catalyst oxides, and establishing an efficient three-phase interface can quickly activate the performance of PEMFCs.

[0003] Existing hydrogen fuel cell activation methods can be broadly categorized into three types: The first type involves constant current or high current activation. The main mechanism is the generation of a large amount of water through high current density, which thoroughly wets the proton exchange membrane and catalyst to reduce proton conduction resistance. However, this method is time-consuming, consumes a large amount of hydrogen, and has poor activation performance. The second type involves high-low potential cycling. The main mechanism is the reduction of oxides on the catalyst surface at low potential and the oxidation of impurities on the catalyst surface at high potential. Simultaneously, the generated water thoroughly wets the proton exchange membrane and catalyst to reduce proton conduction resistance. However, this method is also time-consuming, consumes a large amount of hydrogen, and prolonged operation at low potential can cause catalyst maturation and agglomeration. The third type is the hydrogen pump method. The main mechanism involves introducing hydrogen gas into the anode and an inert gas into the cathode, then forcibly charging the fuel cell with an external power source. The hydrogen gas at the anode is oxidized, releasing hydrogen ions and electrons. The hydrogen ions pass through the proton exchange membrane to reduce oxides in the cathode catalyst. However, this method has a weak activation effect on the catalyst, and the circuitry is complex, difficult to control, and prone to damaging the fuel cell stack.

[0004] CN113224353A discloses a rapid activation device for a proton exchange membrane hydrogen fuel cell. This method mainly includes the following steps: ① stack airtightness testing; ② alternating nitrogen and hydrogen humidification of the anode; ③ variable current charging; ④ high and low potential cycling operation; ⑤ cathode gas supply interruption-recovery cycle. This activation method activates the fuel cell performance through variable current charging and high and low potential cycling operation. However, introducing an external power source makes it difficult to accurately control the charging time of the external current, which can easily damage the stack. Furthermore, this method is only suitable for air-cooled fuel cells and does not consider the characteristics of different fuel cells, thus its applicability is limited.

[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 performance, there is an urgent need in this 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 hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide an activation method for a proton exchange membrane fuel cell. This activation method meets the needs of mass production of fuel cell stacks, thereby reducing hydrogen consumption costs and providing a fast and efficient activation method for fuel cells.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is 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 purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0011] Air immersion: Air is introduced into the cathode of the fuel cell for purging, while nitrogen purging of the anode is stopped; after immersion, humidified fuel is introduced into the anode and humidified oxidant is introduced into the cathode, so that the stack is in an open circuit state until the minimum single-cell open circuit voltage is not lower than 0.95V (e.g., it can be 0.96V, 0.97V, 0.98V, 0.99V, 1.0V, etc.), and maintained for a certain period of time;

[0012] High and low potential cycling: Select constant current loading mode, first load the current at a loading rate of not less than 45A / s (e.g., 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 fuel cell stack drops to 0.5-0.6V (e.g., 0.5V, 0.52V, 0.54V, 0.56V, 0.58V, 0.6V, etc.), and maintain it for a certain period of time; then increase the fuel cell stack voltage to the open circuit voltage at a de-loading rate of not less than 45A / s (e.g., 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 period of time;

[0013] Cathode starvation: Reduce the cathode metering ratio to below 0.8 (e.g., 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 metering ratio for a certain period of time, then restore it to the normal metering ratio and maintain it for a certain period of time.

[0014] In this invention, nitrogen purging removes gas from the anode and cathode pipelines and chambers to prevent irreversible catalyst degradation caused by a hydrogen-air interface at the anode. Then, air immersion removes impurities adhering to the anode catalyst surface. Through rapid potential cycling combined with external high humidification, the stack generates a large amount of water at low potential to rapidly humidify the proton exchange membrane, reducing proton transport resistance. Simultaneously, at high potential, impurities on the cathode catalyst surface are removed. Finally, by starving the cathode at high potential, oxides on the cathode catalyst surface are reduced, significantly improving the stack's performance and rapidly forming a highly efficient and stable three-phase interface transport channel, thus achieving rapid activation of the fuel cell stack.

[0015] Preferably, the nitrogen purging process includes a fuel cell stack airtightness test: checking whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step of nitrogen purging; if no, perform fuel cell stack repair.

[0016] Preferably, the method for testing the gas tightness of the fuel cell stack is as follows: 5.4 gas leakage test and 5.5 gas leakage test in GB / T 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 180 kPa; the maximum working pressure difference in the gas leakage test is 50 kPa, and the maximum operating pressure is 180 kPa.

[0017] Preferably, the airtightness standard is: fuel cell stack leakage rate standard <1mL / min / cell; fuel cell stack external leakage rate standard <21mL / min.

[0018] Preferably, in the nitrogen purging step, the flow rate of nitrogen gas introduced into the anode and cathode of the fuel cell for stack purging is 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 independently 15 to 20 s, for example, 15 s, 16 s, 17 s, 18 s, 19 s, 20 s, etc.

[0019] Preferably, the specific steps for purging the cathode of the fuel cell with air and maintaining gas at the anode are as follows:

[0020] (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 (e.g., 20 kPa, 22 kPa, 24 kPa, 26 kPa, 28 kPa, 30 kPa, 32 kPa, 34 kPa, 36 kPa, 38 kPa, 40 kPa, etc.), and continue to purge the anode with nitrogen gas for 20-40 s (e.g., 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) Turn off the nitrogen purging of the anode and continuously fill the cathode with air for 3 to 5 minutes (e.g., 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, etc.);

[0022] (c) Purge the anode with nitrogen and restore it, and make the anode inlet pressure 10-20 kPa higher than the cathode inlet pressure (e.g., 10 kPa, 12 kPa, 14 kPa, 16 kPa, 18 kPa, 20 kPa, etc.), and maintain the cathode with air purging for 10-30 s (e.g., 10 s, 15 s, 20 s, 25 s, 30 s, etc.).

[0023] Preferably, in the air immersion step, the time maintained until the lowest single-section open-circuit voltage is not lower than 0.95V is more than 10s (e.g., 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 80% or higher (e.g., it can be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 100%, etc.).

[0027] Preferably, the humidifying fuel charging flow rate is 3-5 nlpm / cell, for example, 3 nlpm / cell, 3.5 nlpm / cell, 4 nlpm / cell, 4.5 nlpm / cell, 5 nlpm / cell, etc., and the charging time is 10-30s, for example, 10s, 12s, 14s, 16s, 18s, 20s, 22s, 24s, 26s, 28s, 30s, etc.

[0028] Preferably, the humidifying oxidant has a flow rate of 5-10 nlpm / cell, such as 5 nlpm / cell, 6 nlpm / cell, 7 nlpm / cell, 8 nlpm / cell, 9 nlpm / cell, 10 nlpm / cell, etc., and a charging time of 10-30 s, such as 10 s, 12 s, 14 s, 16 s, 18 s, 20 s, 22 s, 24 s, 26 s, 28 s, 30 s, etc.

[0029] Preferably, the high and low potential cycling step needs to be repeated 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 cycling step further includes supplying the anode and cathode flow rates of the fuel cell stack according to the metering ratio corresponding to the current.

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

[0032] Preferably, the high and low potential cycling step further includes increasing the anode and cathode inlet pressures of the fuel cell stack; wherein the cathode inlet pressure is 250-280 kPa (e.g., 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 (e.g., 10 kPa, 12 kPa, 14 kPa, 16 kPa, 18 kPa, 20 kPa, etc.).

[0033] Preferably, in the high and low potential cycling step, after the voltage drops to 0.5 to 0.6V, it is maintained at this constant current for 120 to 180 seconds (e.g., 120s, 130s, 140s, 150s, 160s, 170s, 180s, etc.).

[0034] Preferably, in the high and low potential cycling 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 more than 5 times (for example, 5, 6, 7, 8, 9, 10 times, etc.), preferably 5 to 8 times.

[0036] Preferably, in the cathode starvation step, the current density is 1.0–1.2 A / cm². 2 (For example, it could be 1.0 A / 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 stoichiometric ratio of the cathode is 0.6 to 0.8 (e.g., 0.6, 0.65, 0.7, 0.75, 0.8, etc.).

[0038] Preferably, after the cathode metering ratio decreases to 0.6-0.8, it needs to be maintained for 6-10 seconds (e.g., 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, etc.).

[0039] Preferably, the cathode metering ratio needs to be maintained for 6 to 10 seconds after it returns to the normal metering ratio (e.g., 6 seconds, 7 seconds, 8 seconds, 9 seconds, 10 seconds, etc.).

[0040] Preferably, the step of cathode starvation is followed by determining that activation is complete:

[0041] Activation is completed by cycling through high and low potentials and performing cathode starvation until the average single-cell 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 this invention, the number of cycles refers to the total number of cycles performed: first, a high-low potential cycle is completed, then a cathode starvation cycle is completed, and then a large mixing cycle is performed.

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

[0045] Preferably, the step of determining that activation is complete further includes stopping and purging:

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

[0047] Disconnect the load, switch the anode to nitrogen gas, and maintain nitrogen purging at the cathode until the HFR value of the fuel cell stack is greater than 0.2 mΩ / cell (e.g., 0.21 mΩ / cell, 0.22 mΩ / cell, 0.25 mΩ / cell, 0.28 mΩ / cell, 0.3 mΩ / cell, etc.), then stop purging.

[0048] Preferably, the current density of the shutdown purging is 0.05–0.1 A / cm². 2 (For example, it could 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 purge time of the fuel cell stack is 2 to 3 minutes (e.g., 2 minutes, 2.2 minutes, 2.4 minutes, 2.6 minutes, 2.8 minutes, 3 minutes, etc.).

[0050] In this invention, the fuel cell purging time refers to the time during which nitrogen gas is maintained at the anode and cathode to reduce the voltage of the fuel cell and remove water accumulation inside the fuel cell.

[0051] As a preferred embodiment of the present invention, the activation method of the proton exchange membrane fuel cell specifically includes the following steps (e.g. Figure 1 As shown):

[0052] S1. Stack airtightness test: Check whether the airtightness of the fuel cell meets the airtightness standard; if yes, proceed to the next step of nitrogen purging; if not, the stack needs to be repaired.

[0053] S2, Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0054] S3. Air Immersion: Purge the cathode of the fuel cell with air, and stop nitrogen purging at the anode; after immersion, charge the anode with humidified fuel and the cathode with humidified oxidant to keep the stack in an open-circuit state until the minimum single-cell open-circuit voltage is not lower than 0.95V and maintain it for a certain period of time; if it is not lower than 0.95V, proceed to the next high and low potential cycle; if the minimum single-cell open-circuit voltage is below 0.95V, perform stack repair.

[0055] S4. High and low potential cycling: Select constant current loading mode, first load the current at a loading rate of not less than 45A / s until the average voltage of the fuel cell stack drops to 0.5~0.6V and maintain it for a certain period of time; then increase the fuel cell stack voltage to the open circuit voltage at a deloading rate of not less than 45A / s and maintain it for a certain period of time.

[0056] S5. Cathode starvation: Reduce the cathode metering ratio to below 0.8, maintain this metering ratio for a certain period of time, then restore it to the normal metering ratio and maintain it for a certain period of time.

[0057] S6. Determine if activation is complete: By cycling through high and low potentials and cathode starvation, continue until the average single-cell voltage under constant current no longer increases or the voltage increase value is not greater than the test error value; if so, activation is complete; otherwise, return to S4 and repeat the high and low potential cycle.

[0058] S7. Shutdown and purging: Supply hydrogen to the anode and nitrogen to the cathode until the average voltage is less than 0.2V; disconnect the load, switch the anode to nitrogen, and maintain nitrogen purging at the cathode until the HFR value of the fuel cell stack is greater than 0.2mΩ / cell, then stop purging.

[0059] This invention first tests the gas tightness of the fuel cell stack using a pressure test bench. Then, a nitrogen purging strategy is employed to purge gases from the anode and cathode pipelines and chambers, preventing irreversible catalyst degradation caused by a hydrogen-air interface at the anode. Subsequently, air immersion is used to remove toxic gases (CO, NO2, SO2) adhering to the anode catalyst surface. Rapid potential cycling is achieved through variable current loading, combined with external high humidification. At low potentials, the stack generates a large amount of water to rapidly humidify the proton exchange membrane, reducing proton transport resistance. Simultaneously, at high potentials, impurities on the cathode catalyst surface are removed. Finally, by starving the cathode at high current density, oxides on the cathode catalyst surface are reduced, significantly improving stack performance and rapidly forming a highly efficient and stable three-phase interface transport channel, achieving rapid activation of the fuel cell stack. Therefore, this invention fully considers the different characteristics of fuel cell membrane electrode catalysts. Using this method, the performance of the fuel cell can be fully activated in a very short time, greatly shortening the activation time and improving 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 includes the following steps:

[0061] S1. Stack airtightness test: Check whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step; if no, the stack needs to be repaired.

[0062] S2, Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0063] S3, Air Immersion: Switch the nitrogen gas to air at the cathode, maintain the cathode inlet pressure 20-40 kPa higher than the anode inlet pressure, and continue purging the anode with nitrogen for 20-40 seconds; then turn off the anode gas purging, and continuously charge the cathode with air for 3-5 minutes; then restore the anode to nitrogen purging, and simultaneously restore the anode inlet pressure to 10-20 kPa higher than the cathode inlet pressure, and maintain the cathode with air purging for 10-30 seconds; finally, charge the anode with humidified fuel and the cathode with humidified oxidant, so that the stack is in an open circuit state until the minimum single-cell open circuit voltage is not lower than 0.95V, and maintain it for 10-30 seconds;

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

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

[0066] S6. Determine if activation is complete: Repeat step S4 (high and low potential cycle) and step S5 (cathode starvation) several times until the average single-cell voltage under constant current no longer increases or the increase value is not greater than the test error value, then activation is complete.

[0067] S7. Shutdown and purging: Set the current density to 0.05–0.1 A / cm². 2 Hydrogen is supplied to the anode and nitrogen to the cathode until the average voltage is less than 0.2V. Then the load is disconnected and the anode is switched to nitrogen. The cathode is purged with nitrogen until the HFR value of the stack is greater than 0.2mΩ / cell, and then the purging is stopped.

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

[0069] (1) The present invention removes the gas in the anode and cathode pipelines and chamber by purging with nitrogen to prevent the anode from having a hydrogen-air interface that causes irreversible degradation of the catalyst; then the impurities attached to the surface of the anode catalyst are removed by air immersion.

[0070] (2) This invention uses rapid potential cycling combined with external high humidification. The stack generates a large amount of water at low potential to rapidly humidify the proton exchange membrane, reducing proton transport resistance. At the same time, at high potential, impurities on the surface of the cathode catalyst can be removed.

[0071] (3) Finally, this invention greatly improves the performance of the fuel cell stack by starving the oxides on the cathode catalyst surface under high electrical density, rapidly forming an efficient and stable three-phase interface transport channel, and realizing the rapid activation of the fuel cell stack.

[0072] (4) The present invention fully considers the characteristics of different catalysts in the membrane electrode of fuel cell. The method of the present invention can be applied to almost all membrane electrodes of fuel cells, and its applicability is extremely wide.

[0073] (5) The present invention can fully activate the performance of fuel cells in a very short time. The entire activation process takes about 45 to 60 minutes, which greatly reduces hydrogen consumption and improves activation efficiency. Attached Figure Description

[0074] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0075] Figure 1 This is a schematic diagram of the process flow for the activation method of the proton exchange membrane fuel cell described in this invention.

[0076] Figure 2 A comparison of performance curves for unactivated, conventionally activated, and rapidly activated fuel cell stacks as provided in Example 1.

[0077] Figure 3 Performance curves for Example 2 with the air immersion step and Comparative Example 1 without the air immersion step.

[0078] Figure 4 The graphs show the performance of Example 4 with the high-low potential fast cycling step and Comparative Example 2 without the high-low potential fast cycling step.

[0079] Figure 5 The graphs show the performance of Example 3 under high electrical density cathode starvation step and Comparative Example 3 under low electrical density cathode starvation step. Detailed Implementation

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

[0081] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0083] Example 1

[0084] This invention provides a general method for rapid activation of proton exchange membrane fuel cells, the method comprising the following steps:

[0085] S1. Stack airtightness test: Check whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step; if no, the stack needs to be repaired.

[0086] S2, Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0087] S3, Air Immersion: Switch the nitrogen gas to air at the cathode, maintain the cathode inlet pressure 20 kPa higher than the anode inlet pressure, and continue purging the anode with nitrogen for 20 seconds; then turn off the anode gas purging, and continuously charge the cathode with air for 3 minutes; then restore the anode to nitrogen purging, and simultaneously restore the anode inlet pressure to 10 kPa higher than the cathode inlet pressure, and maintain the cathode with air purging for 10 seconds; finally, charge the anode with fuel with 100% humidity, and charge the cathode with oxidant with 100% humidity, so that the stack is in an open circuit state until the minimum single-cell open circuit voltage reaches 0.95V, and maintain it for 10 seconds;

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

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

[0090] S6. Determine if activation is complete: Repeat step S4 (high and low potential cycle) and step S5 (cathode starvation) several times until the average single-cell voltage under constant current no longer increases or the increase value is no greater than 2mV, then activation is complete.

[0091] S7. Shutdown and purging: Set the current density to 0.05 A / cm². 2 Hydrogen is supplied to the anode and nitrogen to the cathode until the average voltage is 0.2V. The load is then disconnected and the anode is switched to nitrogen. The cathode is purged with nitrogen until the HFR value of the stack is 0.2mΩ / cell, at which point purging is stopped.

[0092] Example 2

[0093] S1. Stack airtightness test: Check whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step; if no, the stack needs to be repaired.

[0094] S2, Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0095] S3, Air Immersion: Switch the nitrogen gas to air at the cathode, maintain the cathode inlet pressure 30 kPa higher than the anode inlet pressure, and continue purging the anode with nitrogen for 30 seconds; then turn off the anode gas purging and continue to purge the cathode with air for 4 minutes; then restore the anode to nitrogen purging, and simultaneously restore the anode inlet pressure to 20 kPa higher than the cathode inlet pressure, and maintain the cathode with air purging for 20 seconds; finally, purge the anode with fuel with 90% moisture content and purge the cathode with oxidant with 90% moisture content, so that the stack is in an open circuit state until the minimum single-cell open circuit voltage reaches 0.96V, and maintain it for 20 seconds;

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

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

[0098] S6. Determine if activation is complete: Repeat step S4 (high and low potential cycle) and step S5 (cathode starvation) several times until the average single-cell voltage under constant current no longer increases or the increase value is no greater than 2mV, then activation is complete.

[0099] S7. Shutdown and purging: Set the current density to 0.08 A / cm². 2 Hydrogen is supplied to the anode and nitrogen to the cathode until the average voltage equals 0.25V. The load is then disconnected and the anode is switched to nitrogen. The cathode is purged with nitrogen until the HFR value of the stack equals 0.2mΩ / cell, at which point purging is stopped.

[0100] Example 3

[0101] S1. Stack airtightness test: Check whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step; if no, the stack needs to be repaired.

[0102] S2, Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0103] S3, Air Immersion: Switch the nitrogen gas to air at the cathode, maintain the cathode inlet pressure 40 kPa higher than the anode inlet pressure, and continue purging the anode with nitrogen for 20 seconds; then turn off the anode gas purging and continue to purge the cathode with air for 5 minutes; then restore the anode to nitrogen purging, and simultaneously restore the anode inlet pressure to 10 kPa higher than the cathode inlet pressure, and maintain the cathode with air purging for 10 seconds; finally, purge the anode with fuel with 80% moisture content and purge the cathode with oxidant with 80% moisture content, so that the stack is in an open circuit state until the minimum single-cell open circuit voltage reaches 0.95V, and maintain it for 10 seconds;

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

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

[0106] S6. Determine if activation is complete: Repeat step S4 (high and low potential cycle) and step S5 (cathode starvation) several times until the average single-cell voltage under constant current no longer increases or the increase value is no greater than 2mV, then activation is complete.

[0107] S7. Shutdown and purging: Set the current density to 0.1 A / cm². 2 Hydrogen is supplied to the anode and nitrogen to the cathode until the average voltage is 0.2V. The load is then disconnected and the anode is switched to nitrogen. The cathode is purged with nitrogen until the HFR value of the stack is 0.2mΩ / cell, at which point purging is stopped.

[0108] Example 4

[0109] S1. Stack airtightness test: Check whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step; if no, the stack needs to be repaired.

[0110] S2, Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0111] S3, Air Immersion: Switch the nitrogen gas to air at the cathode, maintain the cathode inlet pressure 20 kPa higher than the anode inlet pressure, and continue purging the anode with nitrogen for 10 seconds; then turn off the anode gas purging, and continuously charge the cathode with air for 3 minutes; then restore the anode to nitrogen purging, and simultaneously restore the anode inlet pressure to 20 kPa higher than the cathode inlet pressure, and maintain the cathode with air purging for 20 seconds; finally, charge the anode with fuel with 80% humidity and the cathode with oxidant with 100% humidity, so that the stack is in an open circuit state until the minimum single-cell open circuit voltage reaches 0.95V, and maintain it for 20 seconds;

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

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

[0114] S6. Determine if activation is complete: Repeat step S4 (high and low potential cycle) and step S5 (cathode starvation) several times until the average single-cell voltage under constant current no longer increases or the increase value is no greater than 2mV, then activation is complete.

[0115] S7. Shutdown and purging: Set the current density to 0.05 A / cm². 2 Hydrogen is supplied to the anode and nitrogen to the cathode until the average voltage is 0.2V. The load is then disconnected and the anode is switched to nitrogen. The cathode is purged with nitrogen until the HFR value of the stack is 0.2mΩ / cell, at which point purging is stopped.

[0116] Example 5

[0117] S1. Stack airtightness test: Check whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step; if no, the stack needs to be repaired.

[0118] S2, Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack;

[0119] S3, Air Immersion: Switch the nitrogen gas to air at the cathode, maintain the cathode inlet pressure 40 kPa higher than the anode inlet pressure, and continue purging the anode with nitrogen for 20 seconds; then turn off the anode gas purging and continue to purge the cathode with air for 5 minutes; then restore the anode to nitrogen purging, and simultaneously restore the anode inlet pressure to 10 kPa higher than the cathode inlet pressure, and maintain the cathode with air purging for 10 seconds; finally, purge the anode with fuel with 90% humidity and purge the cathode with oxidant with 100% humidity, so that the stack is in an open circuit state until the minimum single-cell open circuit voltage reaches 0.97V, and maintain it for 10 seconds;

[0120] S4. High and low potential cycling: Turn on the load, select the constant current loading mode, supply the anode and cathode flow of the fuel cell stack according to the metering ratio corresponding to the current, and at the same time increase the anode and cathode inlet pressure of the fuel cell stack. The cathode inlet pressure is 255kPa, and the anode inlet pressure is maintained 10kPa higher than the cathode inlet pressure. The current is rapidly loaded at a loading rate of 54A / s until the average voltage of the fuel cell stack reaches 0.52V. Maintain this constant current for 130s, and then maintain the same deload rate to reduce the fuel cell stack voltage to the open circuit voltage and maintain it for 10s. This step is repeated 3 times before proceeding to the next step.

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

[0122] S6. Determine if activation is complete: Repeat step S4 (high and low potential cycle) and step S5 (cathode starvation) several times until the average single-cell voltage under constant current no longer increases or the increase value is no greater than 2mV, then activation is complete.

[0123] S7. Shutdown and purging: Set the current density to 0.06 A / cm². 2 Hydrogen is supplied to the anode and nitrogen to the cathode until the average voltage is 0.25V. The load is then disconnected and the anode is switched to nitrogen. The cathode is purged with nitrogen until the HFR value of the stack is 0.2mΩ / cell, at which point purging is stopped.

[0124] like Figure 2 As shown in the comparison between the unactivated, conventionally activated, and rapidly activated fuel cell stacks provided by this invention, it can be seen that the method described in this invention greatly improves the performance of the fuel cell stack, quickly forms an efficient and stable three-phase interface transmission channel, and realizes rapid activation of the fuel cell stack.

[0125] Comparative Example 1

[0126] This comparative example provides a method for activating a proton exchange membrane fuel cell. The only difference between this method and Example 2 is that the cathode in S3 is still purged with nitrogen gas instead of air.

[0127] like Figure 3 As shown, this invention uses nitrogen purging to remove gas from the anode and cathode pipelines and chamber, preventing irreversible catalyst degradation caused by hydrogen-air interface at the anode; then, air immersion removes impurities adhering to the surface of the anode catalyst, which is beneficial for subsequent rapid potential cycling; if air immersion is not performed and nitrogen purging is continued, impurities will still adhere to the surface of the anode catalyst, resulting in low activation efficiency.

[0128] Comparative Example 2

[0129] This comparative example provides a method for activating a proton exchange membrane fuel cell. The only difference between this method and Example 4 is that it only performs high-potential cycling instead of high-low-potential rapid cycling.

[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 rapidly humidify the proton exchange membrane, reducing proton transport resistance. At the same time, at high potential, impurities on the surface of the cathode catalyst can be removed.

[0131] Comparative Example 3

[0132] This comparative example provides a method for activating a proton exchange membrane fuel cell. The only difference between this method and Example 3 is that cathode starvation is performed at a low electrical density of 0.2 A / cm³. 2 .

[0133] like Figure 5 As shown, by starving the oxides on the cathode catalyst surface under high electrical density, the performance of the fuel cell stack is greatly improved, and a highly efficient and stable three-phase interface transport channel is quickly formed, thereby achieving rapid activation of the fuel cell stack.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 includes the following steps: Nitrogen purging: Nitrogen gas is introduced into the anode and cathode of the fuel cell to purge the fuel cell stack; Air immersion: Air is introduced into the cathode of the fuel cell for purging, while nitrogen purging of the anode is stopped; after immersion, humidified fuel is introduced into the anode and humidified oxidant is introduced into the cathode to keep the stack in an open circuit state until the minimum single-cell open circuit voltage is not lower than 0.95 V and is maintained for a certain period of time. The specific steps of the air purging are as follows: (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, and continue to purge the anode with nitrogen for 20-40 seconds; (b) turn off the nitrogen purging at the anode, and continuously purge the cathode with air for 3-5 minutes; (c) restore the nitrogen purging at the anode, and make the anode inlet pressure 10-20 kPa higher than the cathode inlet pressure, and maintain the cathode with air purging for 10-30 seconds. High and low potential cycling: Select constant current loading mode, first load the current at a loading rate of not less than 45 A / s until the average voltage of the fuel cell stack drops to 0.5~0.6V, and maintain it for a certain period of time; then increase the fuel cell stack voltage to the open circuit voltage at a deloading rate of not less than 45 A / s, and maintain it for a certain period of time. Cathode starvation: Reduce the cathode metering ratio to 0.6~0.8, maintain this metering ratio for 6~10 s, then restore it to the normal metering ratio and maintain it for another 6~10 s; In the cathode starvation step, the current density is 1.0~1.2 A / cm². 2 .

2. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, The nitrogen purging process also includes a fuel cell stack airtightness test: checking whether the fuel cell airtightness meets the airtightness standard; if yes, proceed to the next step of nitrogen purging; if not, perform fuel cell stack repair.

3. The activation method for a proton exchange membrane fuel cell according to claim 2, characterized in that, The method for testing the gas tightness of the fuel cell stack is as follows: the gas leakage test (5.4) and the gas leakage test (5.5) in GB / T 20042.2-2023 Proton Exchange Membrane Fuel Cell Part 2 General Technical Conditions for Fuel Cell Stacks are adopted. The maximum working pressure in the gas leakage test is 180 kPa; the maximum working pressure difference in the gas leakage test is 50 kPa, and the maximum operating pressure is 180 kPa.

4. The activation method for a proton exchange membrane fuel cell according to claim 2, characterized in that, The airtightness standards are: fuel cell stack leakage rate <1 mL / min / cell; fuel cell stack external leakage rate <21 mL / min.

5. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the nitrogen purging step, the flow rate of nitrogen gas introduced into the anode and cathode of the fuel cell for stack purging is independently 0.8~1.2 sccm / cell sccm, and the stack purging time is independently 15~20 s.

6. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, During the air immersion step, the minimum single-section open-circuit voltage is maintained at 0.95 V for at least 10 seconds.

7. The activation method for a proton exchange membrane fuel cell according to claim 6, characterized in that, The duration is 10~30 seconds.

8. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the air immersion step, the fuel is hydrogen.

9. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the air immersion step, the oxidant is air and / or oxygen.

10. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the air soaking step, the humidity of the humidified fuel and the humidified oxidant is above 80%.

11. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the air soaking step, the humidified fuel is introduced at a flow rate of 3-5 nlpm / cell and for a time of 10-30 s.

12. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the air immersion step, the flow rate of the humidifying oxidant is 5~10 nlpm / cell, and the immersion time is 10~30 s.

13. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, The high and low potential cycling steps need to be repeated at least 3 times.

14. The activation method for a proton exchange membrane fuel cell according to claim 13, characterized in that, The cycle is repeated 3 to 4 times.

15. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, The high and low potential cycling step also includes supplying the anode and cathode flow rates of the fuel cell stack according to the metering ratio corresponding to the current.

16. The activation method for a proton exchange membrane fuel cell according to claim 15, characterized in that, The measurement ratio is 1.5 to 2.

17. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, The high and low potential cycling step also includes increasing the anode and cathode inlet pressures of the fuel cell 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.

18. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the high and low potential cycling step, after the voltage drops to 0.5~0.6V, it is maintained at this constant current for 120~180 s.

19. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, In the high and low potential cycling step, the voltage is increased to the open circuit voltage and then maintained for 10~20 seconds.

20. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, The cathode starvation step needs to be repeated more than 5 times.

21. The activation method for a proton exchange membrane fuel cell according to claim 20, characterized in that, The cycle is repeated 5 to 8 times.

22. The activation method for a proton exchange membrane fuel cell according to claim 1, characterized in that, The cathode starvation step is followed by a determination that activation is complete: Activation is completed by cycling through high and low potentials and performing cathode starvation until the average single-cell voltage under constant current no longer increases or the voltage increase value is no greater than the test error value.

23. The activation method for a proton exchange membrane fuel cell according to claim 22, characterized in that, The cycle is repeated at least three times.

24. The activation method for a proton exchange membrane fuel cell according to claim 23, characterized in that, The cycle is repeated 3 to 5 times.

25. The activation method for a proton exchange membrane fuel cell according to claim 22, characterized in that, The error value is 2 mV.

26. The activation method for a proton exchange membrane fuel cell according to claim 22, characterized in that, The step of determining that activation is complete also includes stopping the machine and purging: Hydrogen is supplied to the anode and nitrogen to the cathode until the average voltage is less than 0.2 V; Disconnect the load, switch the anode to nitrogen, and maintain nitrogen purging at the cathode until the HFR value of the fuel cell stack is greater than 0.2 mΩ / cell, then stop purging.

27. The activation method for a proton exchange membrane fuel cell according to claim 26, characterized in that, The current density for the shutdown purging is 0.05~0.1 A / cm². 2 .

28. The activation method for a proton exchange membrane fuel cell according to claim 26, characterized in that, The fuel cell purging time is 2-3 minutes.

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