Method and system for activation of a hydrogen fuel cell stack

Abstract

The application provides an activation method and system of a hydrogen fuel cell stack, and belongs to the technical field of stack activation. The method solves the problem that the activation effect of the prior art is difficult to guarantee and the performance of the whole stack is difficult to improve comprehensively. The method comprises the following steps: performing stack pressing and assembling on a finished product stack, and performing insulation detection and air tightness detection; loading a high-power stack that passes the insulation detection and the air tightness detection to a limit maximum current, continuously performing high-low voltage loading, so as to perform initial state activation and polarization of the stack until the internal water balance of the stack is identified to reach an optimal state, and the initial state activation and polarization are ended; selecting a value in a high current density range of 0.2-2.5 A / cm 2 , and controlling the high-power stack to run at the value as an output for a set time, so as to perform constant-time high-current activation of the stack; closing an air path, performing shutdown purging on the high-power stack in an idle state through a hydrogen path until the output voltage of the high-power stack is 0, and completing one activation cycle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stack activation, and particularly relates to a hydrogen fuel cell stack activation method and system. BACKGROUND

[0002] Vehicle-mounted hydrogen fuel cell engines have a series of advantages such as high energy conversion efficiency, strong environmental friendliness, wide fuel sources, and the ability to provide sufficient electric energy as driving force for vehicles, and are considered as an effective way to replace traditional energy sources. With the continuous development of hydrogen fuel cell technology, the complexity of vehicle working conditions and the severity of heavy truck application scenarios are continuously deepening, which greatly impacts the durability performance of the core component of the engine, i.e., the stack. Performance improvement and performance recovery of the stack are key problems to be solved in the field of hydrogen fuel cell applications.

[0003] In the prior art, different methods are used to deal with different use links of the fuel cell stack, such as stack level membrane electrode pre-moistening activation, frequent variable load high and low load activation, constant voltage and constant current control method activation, electrolysis activation method, and large current impact activation. The verification of the above stack activation methods basically stays at the short stack or single cell level, and the activation process involving the whole stack and the product is less. Some activation methods, such as the constant current mode, occupy a large amount of activation test resources, and the energy consumption is relatively obvious, but the effect is not very significant.

[0004] The patent CN112952149B proposes to use deionized water with a certain temperature or humidified gas such as nitrogen, helium, air or hydrogen to pretreat the membrane electrode. During the operation process, it is difficult to control the uniformity of the wetting of the electrode and the convenience of the operation of the tooling, there are many intermediate conversion links, the process is also relatively complex, and under the condition of incomplete treatment, the membrane electrode may even be damaged.

[0005] The patent CN108232243A passes humidified nitrogen into the cathode and humidified hydrogen into the anode at the initial activation stage, performs pressure maintaining verification, controls the stack temperature through water circulation, maintains pressure for 2-3 hours, performs 5-10 rounds of polarization performance test, and then performs nitrogen humidification pressure maintaining until the polarization performance is stable. However, the number of cycles is too large, a large amount of pressure maintaining and polarization time is consumed, and the commercial batch production demand cannot be met.

[0006] The patent CN110137538A proposes to use an electrical control method to realize the on-off control of the IGBT discharge current between the stack and the load DC-DC, to remove the impurities on the membrane surface by shocking the membrane electrode, and finally to achieve the purpose of improving the electric performance. This scheme only improves the electric performance of the proton exchange membrane, and cannot comprehensively improve the electric performance of the catalyst layer. At the same time, the instantaneous discharge current is large, 500-700 A, and the bearing capacity of the electrical components is greatly impacted and tested.

[0007] The aforementioned patented solutions also involve significant testing resource usage and energy consumption, and some operations fail to meet industrial-grade safety standards, posing numerous safety risks. Currently, the development of a highly efficient, full-process activation method for fuel cell systems is crucial for the industrialization of fuel cell stacks. Summary of the Invention

[0008] In view of the above analysis, the embodiments of the present invention aim to provide a method and system for activating a hydrogen fuel cell stack, so as to solve the problem that the activation effect of the prior art is difficult to ensure and the performance of the entire stack is difficult to improve.

[0009] In one aspect, an embodiment of the present invention provides a method for activating a hydrogen fuel cell stack, comprising the following steps:

[0010] S1. Stack and press-assemble the finished fuel cell stacks, and perform insulation and airtightness tests on the pressed high-power fuel cell stacks;

[0011] S2. Load the high-power fuel cell stack that has passed the insulation and airtightness tests to its maximum current limit, continuously applying high and low voltage loads to perform initial activation and polarization of the stack until the stack's internal water balance reaches an optimal state, completing initial activation and polarization.

[0012] S3. According to the operating conditions, between 0.2 and 2.5A / cm 2 A value is selected within the high current density range, and the high-power fuel cell stack is controlled to set the activation load time for output operation at this value to perform constant-time high-current activation of the fuel cell stack;

[0013] S4. Close the air path, maintain the hydrogen supply, and perform a no-load shutdown purge on the high-power fuel cell stack until its output voltage drops to 0, completing an activation cycle.

[0014] The beneficial effects of the above technical solution are as follows: a highly efficient full-process stack and system activation method is proposed for stack performance recovery, ultimately meeting the needs of mass technology research and development, production testing, and on-vehicle performance recovery. This method reduces costs at each stage, improves stack activation efficiency, and saves time at each stage. Using finished high-power stacks, the stack test bench is combined with an external load to achieve different operating conditions and load control, enabling stack performance activation and reversible attenuation recovery under different operating conditions.

[0015] Based on the further improvement of the above method, the method is applied to newly developed finished fuel cell stacks, finished fuel cell stacks in the process of research and development, or finished fuel cell stacks that have been stored for a long time after leaving the factory; and,

[0016] The activation cycle is performed more than once, and the output voltage of the high-power fuel cell stack is obtained after each activation cycle, and the activation cycle is terminated until the output voltage of the high-power fuel cell stack reaches the target voltage value.

[0017] Furthermore, for the finished fuel cell stack that has been stored for a long time after leaving the factory, steps S2 to S4 are repeated for 6 to 8 activation cycles to overcome the fuel cell stack performance degradation caused by the long storage of the fuel cell stack.

[0018] Furthermore, step S1 further includes:

[0019] S11. The finished fuel cell stack is assembled by a press-fit process to obtain a high-power fuel cell stack after press-fitting;

[0020] S12. Collect basic data before activation of the high-power stack after pressing, and record the basic data before activation;

[0021] S13. Perform insulation testing on the press-assembled stack, and filter out high-power stacks whose insulation test results do not meet the standards based on the insulation parameters in the basic data before activation;

[0022] S 14. The high-power fuel cell stacks that meet the insulation test standards are further subjected to air tightness testing. Combined with the air tightness parameters in the basic data before activation, the high-power fuel cell stacks that do not meet the air tightness test standards are screened out to obtain high-power fuel cell stacks that pass the insulation test and the air tightness test.

[0023] Furthermore, the basic data before activation include size, volume, mass, tooling flatness data information, press force accuracy information, press stroke information, stack free state height, height after press assembly, average shrinkage per single section, stack size, stack weight, equivalent core mass power density, equivalent core volume power density, stack dry and wet insulation parameters, stack single cavity air tightness, three cavity pressure maintaining air tightness, and leakage data information; among them,

[0024] The insulation parameters in the basic data before activation include the dry and wet insulation parameters of the stack;

[0025] The airtightness parameters in the basic data before activation include the stack single-cavity airtightness, three-cavity pressure-maintaining airtightness, and leakage data information;

[0026] The insulation test includes: testing the insulation resistance between the positive electrode of the battery stack and the metal part of the battery stack PACK shell, and the insulation resistance between the negative electrode of the battery stack and the metal part of the battery stack PACK shell, as the actual insulation measurement data, to verify whether the actual insulation measurement data is within the insulation parameter range of the basic data before activation; and,

[0027] The air tightness test includes: testing the single-cavity air tightness of the fuel cell stack, the three-cavity pressure-maintaining air tightness, and the leakage data respectively, and verifying whether the actual measured data of the single-cavity air tightness of the fuel cell stack, the three-cavity pressure-maintaining air tightness, and the leakage are all within the respective air tightness parameter ranges in the basic data before activation.

[0028] Furthermore, step S2 further includes:

[0029] S21. Determine the limiting current conditions and maximum current of the high-power stack based on the actual stack load requirements;

[0030] S22. Load the high-power fuel cell stack that has passed the insulation and airtightness tests to the maximum current limit according to the above-mentioned limiting current conditions to open the mass transfer channels within the fuel cell stack, establish the gas, liquid, and fixed three-phase interface within the fuel cell stack, promote electrochemical reactions, and improve the performance of the high-power fuel cell stack;

[0031] S23. Continuously applying high and low voltage loading to the high-power stack at the maximum current limit to perform initial activation and polarization of the stack and adjust the water balance within the stack;

[0032] S24. During the loading process, monitor whether the internal water balance of the fuel cell stack has reached the optimal state, until it is identified that the internal water balance of the fuel cell stack has reached the optimal state, and end the initial state activation and polarization of the fuel cell stack.

[0033] Furthermore, step S3 further includes:

[0034] S31. According to the operating conditions, 0.2~2.5A / cm 2 A value is selected within the high current density range;

[0035] S32. Based on the high current density selected above, a low air stoichiometric ratio is selected for air in the low stoichiometric ratio of 1 to 1.5, and a low hydrogen stoichiometric ratio is selected for hydrogen in the stoichiometric ratio of 1 to 1.5;

[0036] S33. Control the high-power fuel cell stack to operate with the selected high current density as output and the selected low air stoichiometric ratio and hydrogen stoichiometric ratio as input, and set the activation load time to perform constant-time high-current activation of the fuel cell stack; during operation, the temperature of hydrogen is equal to the temperature of air, and the dew point temperature of hydrogen is equal to the dew point temperature of air.

[0037] Furthermore, step S4 further includes:

[0038] Disconnect all loads on the high-power stack;

[0039] Close the air path, maintain the hydrogen supply, and perform a no-load shutdown purge on the high-power fuel cell stack;

[0040] During the purging process, the output voltage of the high-power stack is monitored until the output voltage thereof is reduced to 0, the hydrogen path is closed, the shutdown of the high-power stack is performed, and one activation cycle is completed.

[0041] Further, the shutdown time of the high-power stack is 10-25 min; and,

[0042] During each activation cycle, the stack is pulled by an external load, and the external load is a variable load.

[0043] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0044] 1. The present application can be used for improving and enhancing the electrical performance of newly developed stacks to reach the preset target voltage value; can be used for activating and polarizing the performance of stacks during the research and development process to enhance the performance of the fuel cell system and reach the preset system voltage target value; can be used for activating the long-stored stacks and engines after delivery to restore their electrical performance and enhance their reliability. The application range of the activation condition is expanded.

[0045] 2. During the design and use of the activation condition, the technical problem that different state conditions cannot be universally used is solved, the use scene of the condition is changed by controlling the external carrier, the performance activation and performance regeneration process after the attenuation of the test stack, the engine and the vehicle scene during the research and development process can be operated under unified conditions, the technical problem that different conditions cannot be universally used is solved, and the operation time is saved. The activation condition operation is convenient, and the universality is improved.

[0046] 3. According to the performance of the engine in different states, the activation pull time and the start-stop time of the activation pull are evaluated, the overall activation time is controlled by designing the shutdown strategy, the activation time is reduced by a certain proportion according to the dry and wet degree of the stack in different states, and the problem of long-time activation in the past is finally solved. The cycle condition and the reduction amplitude of the activation time under different performance conditions.

[0047] 4. The electrical performance of the engine on the market is reversibly attenuated, the electrical performance regeneration of the stack restores the operation performance, and benefits from the initial state high-low variable load activation polarization and the constant current discharge process control strategy.

[0048] 5. The stack activation method is simplified, the operation convenience of the activation process is improved, the activation time is reduced, and the work efficiency is improved.

[0049] On the other hand, the embodiment of the present application provides an activation device for a hydrogen fuel cell stack, which comprises a stack test bench, and a stack pressing and detecting device, an initial activation device and a large-current activation device arranged on the test bench.

[0050] Stacking, pressing, and testing equipment, used to stack and press-assemble finished fuel cell stacks, and perform insulation and airtightness tests on the pressed high-power fuel cell stacks; and to output the high-power fuel cell stacks that have undergone insulation and airtightness tests to the initial activation equipment;

[0051] Initial activation equipment is used to load the high-power fuel cell stack that has passed the insulation test and the airtightness test to the maximum current limit, and continuously perform high and low voltage loading to perform initial state activation and polarization of the fuel cell stack until it is identified that the internal water balance of the fuel cell stack has reached the optimal state. The initial state activation and polarization of the fuel cell stack are completed, and the high-power fuel cell stack is output to the high-current activation equipment;

[0052] High current activation equipment, used for 0.2~2.5A / cm 2 A value is selected within the high current density range, and the high-power fuel cell stack is controlled to set the activation load time for output operation at this value to perform constant-time high-current activation of the fuel cell stack; and, after the set activation load time is reached, the air path is closed, the hydrogen path is maintained for supply, and the high-power fuel cell stack is shut down and purged in a no-load state until its output voltage drops to 0, completing an activation cycle; and, the high-power fuel cell stack is output to the initial activation equipment until it is shut down after completing the set number of activation cycles.

[0053] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the invention, nor is it intended to limit the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0055] Figure 1 A schematic diagram of the activation method for a hydrogen fuel cell stack according to Example 1 is shown;

[0056] Figure 2 A schematic diagram of the control flow involved in the activation method of Example 2 is shown;

[0057] Figure 3 A schematic diagram showing the results of the stack load polarization test before and after activation in Example 2 is shown;

[0058] Figure 4 A schematic diagram of the stack load reduction polarization test results before and after activation of Example 2 is shown. DETAILED DESCRIPTION

[0059] Embodiments of the present application will be described below in greater detail with reference to the accompanying drawings. While embodiments of the present application are shown in the drawings, it is understood that the present application can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0060] As used herein, the term "includes" and its variants are meant to be an open-ended term that means "comprises, but not limited to." The term "or" means "and / or" unless otherwise noted. The term "based on" means "based, at least in part, on." The terms "one example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," and the like can refer to different or identical objects. Other explicitly and implicitly recited definitions can also be included below.

[0061] Embodiment 1

[0062] One embodiment of the present application discloses an activation method of a hydrogen fuel cell stack, as shown in the following steps: Figure 1

[0063] S1. Stack and press the finished product stack, and perform insulation detection and air tightness detection on the high-power stack after pressing;

[0064] S2. Load the high-power stack that passes the insulation detection and air tightness detection to the limit maximum current, and continuously perform high-low voltage loading to execute the initial state activation and polarization of the stack until the internal water balance of the stack is identified to reach the optimal state, and the initial state activation and polarization of the stack is ended;

[0065] S3. According to the operating condition, select a value in the high current density range of 0.2-2.5 A / cm 2 , control the high-power stack to run at the value as the output to set the activation loading time, and execute the constant time high current activation of the stack;

[0066] S4. Close the air path, keep the hydrogen path supply, and perform the shutdown purge of the high-power stack in the no-load state until its output voltage drops to 0, and complete one activation cycle.

[0067] ​Compared with the prior art, the activation method of the hydrogen fuel cell stack provided by the embodiment proposes a high-efficiency whole-process stack and system activation method for stack performance recovery, ultimately meeting the needs of batch technology research and development, production testing, and vehicle performance recovery. The method saves the cost of each link, improves the efficiency of stack activation, and saves the operation time of each link. Through the finished high-power stack, the stack test bench and the external load are cooperated to realize different operating conditions and load control, and the stack performance activation and reversible attenuation recovery under different working conditions are realized.

[0068] Embodiment 2

[0069] Based on the improvement of embodiment 1, the method is applied to a newly developed finished stack, a finished stack in the research and development process, or a finished stack after leaving the factory for a long time. Moreover, the activation cycle is not only once, and the output voltage of the high-power stack is obtained after each activation cycle, until the output voltage of the high-power stack reaches the target voltage value, and the activation cycle ends.

[0070] For a newly developed finished stack, the operating condition design and start-stop working condition design can be completed through the stack test bench to achieve the activation purpose of the stack test bench and improve the electrical performance of the stack.

[0071] For a finished stack in the research and development process, the performance improvement and attenuation recovery of the stack in the research and development process are realized by corresponding working condition information and actual control strategy design and optimization, the durability of the engine in the research and development process is improved, the foundation for new product research and development process is laid, the product development week is shortened, and the development personnel work efficiency is improved.

[0072] For a finished stack after leaving the factory for a long time, in the process of using the market operation client, the engine uses the "performance regeneration working condition", and the program can adaptively judge the attenuation rate of each working condition. The recovery working condition can be automatically run, the engine performance can be greatly regenerated, the market operation effect can be ensured, and the client performance can be improved.

[0073] Preferably, for a finished stack after leaving the factory for a long time, steps S2-S4 are repeated for 6-8 activation cycles to overcome the stack performance attenuation caused by the long storage of the stack.

[0074] In summary, in the activation working condition design and use process, the technical problem that different state working conditions cannot be universally used can be solved. By controlling the carrier to change the working condition use scene (changing the high current density in step S3, the set activation load time of running), the performance activation and attenuation performance regeneration process of the trial stack, the engine in the research and development process, and the whole vehicle scene under the unified conditions can be realized. The technical problem that different working conditions cannot be universally used is solved, and the operation time is saved.

[0075] Preferably, step S1 further comprises:

[0076] S11. Assembling the finished stack through a press-fitting process to obtain a press-fitted high-power stack;

[0077] S12. Collecting the pre-activation basic data of the press-fitted high-power stack and recording the pre-activation basic data; preferably, the pre-activation basic data includes size, volume, mass, tool flatness data information, press-fitting force accuracy information, press stroke information, stack free state height, post-press-fitting height, average to single shrinkage, stack size, stack weight, equivalent core mass power density, equivalent core volume power density, dry and wet state insulation parameters of the stack, single cavity airtightness of the stack, three-cavity pressure-maintaining airtightness, and data information of leakage;

[0078] S13. Insulating detection of the press-fitted stack, and screening out the high-power stack with substandard insulating detection results in combination with the insulation parameters in the pre-activation basic data; preferably, the insulation parameters in the pre-activation basic data include dry and wet state insulation parameters of the stack;

[0079] S14. Further airtightness detection of the high-power stack with standard insulating detection results, and screening out the high-power stack with substandard airtightness detection results in combination with the airtightness parameters in the pre-activation basic data to obtain the high-power stack passing the insulating detection and airtightness detection. Preferably, the airtightness parameters in the pre-activation basic data include single cavity airtightness of the stack, three-cavity pressure-maintaining airtightness, and data information of leakage.

[0080] Preferably, the insulating detection includes testing the insulation resistance between the positive electrode of the stack and the metal part of the stack PACK shell and the insulation resistance between the negative electrode of the stack and the metal part of the stack PACK shell respectively as the actual measurement data of the insulation, and verifying whether the actual measurement data of the insulation is within the range of the insulation parameters in the pre-activation basic data.

[0081] Preferably, the airtightness detection includes testing the single cavity airtightness of the stack, the three-cavity pressure-maintaining airtightness, and the leakage data respectively, and verifying whether the actual measurement data of the single cavity airtightness of the stack, the three-cavity pressure-maintaining airtightness, and the leakage respectively are within the range of the respective airtightness parameters in the pre-activation basic data.

[0082] Preferably, step S2 further includes:

[0083] S21. Determining the limit current condition and the limit maximum current of the high-power stack according to the actual stack load demand;

[0084] S22. Load the high-power fuel cell stack that has passed the insulation and airtightness tests to the maximum current limit according to the above-mentioned limiting current conditions to open the mass transfer channels within the fuel cell stack, establish the gas, liquid, and fixed three-phase interface within the fuel cell stack, promote electrochemical reactions, and improve the performance of the high-power fuel cell stack;

[0085] S23. Continuously apply high and low voltage loading to the high-power stack at this maximum current limit (i.e., sequentially apply loading and discharge to the high-power stack at high and low potentials, where high potential is greater than 0.8V and low potential is less than 0.45V) to perform initial activation and polarization of the stack and regulate the water balance within the stack.

[0086] S24. During the loading process, monitor whether the internal water balance of the fuel cell stack has reached the optimal state, until it is identified that the internal water balance of the fuel cell stack has reached the optimal state, and end the initial state activation and polarization of the fuel cell stack.

[0087] Specifically, step S24 may collect the voltage values ​​of the stack at different current density points (different current densities) and determine whether the difference between the voltage values ​​at different current density points and the design values ​​is within the range of (0.65±0.003) V. If so, it is determined that the stack has reached the optimal water balance state; otherwise, it has not reached the optimal water balance state. Optionally, the optimal water balance state can also be monitored using the method disclosed in existing patent CN201711372804.4.

[0088] Preferably, in each activation cycle, in step S22 , the stack is loaded to the above-mentioned maximum current limit by an external load, and the external load is a variable load.

[0089] Through steps S21-S24, the maximum current is continuously applied at varying levels, with the load being pulled to the maximum current according to the actual stack capacity requirements. This is done to open the mass transfer channels within the stack and improve its performance. By varying the load, the water balance within the stack is further adjusted, which facilitates the wetting of the proton membrane and optimizes the internal water balance of the stack.

[0090] Preferably, step S3 further comprises:

[0091] S31. According to the operating conditions, 0.2~2.5A / cm 2 A value is selected within the high current density range;

[0092] S32. Based on the high current density selected above, a low air stoichiometric ratio is selected for air in the low stoichiometric ratio of 1 to 1.5, and a low hydrogen stoichiometric ratio is selected for hydrogen in the stoichiometric ratio of 1 to 1.5;

[0093] S33. Control the high-power fuel cell stack to operate with the selected high current density as output and the selected low air stoichiometric ratio and hydrogen stoichiometric ratio as input, and set the activation load time to perform constant-time high-current activation of the fuel cell stack; during operation, the temperature of hydrogen is equal to the temperature of air, and the dew point temperature of hydrogen is equal to the dew point temperature of air.

[0094] Through steps S31 to S33, as shown in Table 1, constant current discharge activation is performed, the current density is designed according to the voltage conditions, the stable voltage is set to 0.45V, the floating voltage value is ±0.05V, the minimum alarm threshold is 0.3V, the maximum voltage value is set to 0.5V, the air and hydrogen operating inlet pressures are constant, the hydrogen flow rate is normal, the air adopts a low stoichiometric ratio intake scheme, and during the voltage control process, the low stoichiometric ratio scheme is adopted to reduce the voltage of a single cell of the stack. The working condition is stable for 45 minutes.

[0095] Different activation loading times are set for different engine performance conditions. By designing a shutdown strategy to control the overall activation time, the activation time can be reduced by a certain percentage based on the dryness and wetness of the fuel cell stack in different states, which can solve the problem of long activation time in existing technologies. Through the use of finished high-power fuel cell stacks, the fuel cell test bench is combined with external loads to achieve different operating conditions and load control, realizing fuel cell performance activation and reversible attenuation recovery under different operating conditions.

[0096] Preferably, step S4 further comprises:

[0097] S41. Disconnect all loads on the high-power stack;

[0098] S42. Close the air path, maintain the hydrogen path supply, and perform a no-load shutdown purge on the high-power stack;

[0099] S43. During the purge process, monitor the output voltage of the high-power stack until the output voltage drops to 0, close the hydrogen line, and shut down the high-power stack to complete one activation cycle. Preferably, the shutdown time of the high-power stack is 10 to 25 minutes.

[0100] Through steps S41 to S43, the high-power fuel cell stack enters the load dumping shutdown process. The key information in this process refers to the shutdown purge conditions in Table 2. The load is disconnected, the air path is closed, and the hydrogen path is continuously purged with low electrical density. Due to the active discharge of oxygen consumption during the closing of the air path, the voltage slowly decreases to 0V and then the hydrogen is turned off, and finally the cooling cycle is stopped. The entire system is shut down for 15 minutes, thereby completing an activation cycle.

[0101] During implementation, typical test operating conditions in step S3 are shown in Table 1. A higher current density and a lower air-to-hydrogen stoichiometric ratio were selected for stack operation. During the process, the gas temperature and dew point were kept stable under high temperature and high humidity conditions for 45 minutes. The single pressure fluctuation met the design requirements, and the cooling system parameters met the stack operation requirements.

[0102] Table 1 Stack activation constant current discharge operating conditions

[0103]

[0104]

[0105] The corresponding shutdown and activation working condition information is shown in Table 2. Select the no-load shutdown purge, maintain the hydrogen supply, stop the air supply, and run the engine at room temperature until the voltage drops to 0V and shuts down. Finally, stop the hydrogen supply, and the shutdown time is 15 minutes.

[0106] Table 2 Shutdown and activation working condition information

[0107]

[0108]

[0109] The overall implementation process is as follows Figure 2 shown.

[0110] During the activation process of the entire stack, after several cycles of steps S2 to S4 are performed, a performance polarization test is performed to obtain the polarization performance curves of the high-power stack before and after activation. Figure 3 、 Figure 4 As shown in the figure, after cycling this method, the high-power stack achieved performance gains ranging from 14mV to 18mV under the same load conditions, both during load increases and decreases. After 6 to 8 cycles, the high-power stack reached its designed performance parameters, verifying that this method can fully address the performance degradation caused by long-term storage.

[0111] Through comparative analysis and verification of the data, and subsequent verification with the AC impedance function of a single battery, the monitoring of the water balance status within the fuel cell stack can be further improved. During the high-current and frequent load-changing process, the application of AC impedance can further determine the hydration effect of the gas diffusion layer and catalytic layer on the polymer in each link of the fuel cell stack's core components, clarify the effect and benefits of mass transfer, and further clarify the process of improving fuel cell stack performance. During the continuous discharge process at a constant current, a gas and liquid transmission channel is established through a large gas flow, removing impurities in the electrode preparation process and further improving fuel cell stack performance.

[0112] Compared with the prior art, the activation method of the hydrogen fuel cell stack provided in this embodiment has the following beneficial effects:

[0113] 1. The method can be used for improving and upgrading the electrical performance of newly developed stacks to reach the preset target voltage value. It can also be used for activating and polarizing the performance of stacks during the research and development process to improve the performance of fuel cell systems and reach the preset system voltage target value. It can also be used for activating long-stored stacks and engines after delivery to restore their electrical performance and improve reliability. The application range of activation conditions is expanded.

[0114] 2. During the design and use of the activation condition, the technical problem of different state conditions not being universally applicable is solved. By controlling the external carrier to change the working condition of the use scene, the performance activation and performance regeneration process after performance degradation of the trial stack, the engine during the research and development process, and the vehicle scene can be operated under unified conditions. The technical problem of different working conditions not being universally applicable is solved, and the operation time is saved. The activation condition operation is convenient, and the universality is improved.

[0115] 3. According to the performance of the engine in different states, the activation load time and the start-stop time of the activation load are evaluated. By designing a shutdown strategy, the overall activation time is controlled. According to the dry and wet degree of the stack in different states, the activation time is reduced by a certain proportion, and the problem of long activation time in the past is finally solved. The cycle situation under different performance conditions and the reduction amplitude of the activation time.

[0116] 4. The electrical performance of the engine on the market is reversibly degraded. The electrical performance regeneration of the stack restores the operational performance, which benefits from the initial state high-low load activation polarization-constant current discharge process control strategy.

[0117] 5. The stack activation method is simplified, the operation convenience of the activation process is improved, the activation time is reduced, and the work efficiency is improved.

[0118] Embodiment 3

[0119] The application also discloses an activation device of a hydrogen fuel cell stack using the method of Embodiment 1 or 2, which comprises a stack test bench, and a stack pressing and detecting device, an initial activation device, and a high-current activation device arranged on the test bench.

[0120] The stack pressing and detecting device is used for stacking and pressing the finished stack, and detecting the insulation and air tightness of the high-power stack after pressing. The high-power stack after insulation and air tightness detection is output to the initial activation device. The detection components in the stack pressing and detecting device further comprise an air tightness testing device and a performance testing fluid switching device.

[0121] The initial activation device is used to pull the high-power stack passing through the insulation detection and the air tightness detection to the limit maximum current, continuously carries out the high-low voltage pull, so as to perform the initial state activation and polarization of the stack, until the internal water balance of the stack is identified to reach the optimal state, the initial state activation and polarization of the stack is ended, and the high-power stack is output to the high-current activation device.

[0122] The high-current activation device is used to select a value in the high current density range of 0.2-2.5 A / cm 2 , according to the operation condition, control the high-power stack to run with the value as the output to set the activation pull time, so as to perform the constant time high-current activation of the stack; and after the set activation pull time is reached, the air path is closed, the hydrogen path is kept to supply, the idle state shutdown purging of the high-power stack is performed until the output voltage is reduced to 0, and one activation cycle is completed; and the high-power stack is output to the initial activation device until the shutdown is performed after the set number of activation cycles is completed.

[0123] Preferably, the test bench is provided with an external load with adjustable load.

[0124] In the implementation, the stack test bench and the external load are matched to realize different operation conditions and load control through the finished high-power stack, so as to realize the stack performance activation and reversible attenuation recovery under different working conditions.

[0125] The above has described the embodiments of the present application, the above description is exemplary, is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application or improvement of the prior art of the embodiments, or to enable other ordinary skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for activating a hydrogen fuel cell stack, characterized in that: The steps include: S1. Stack and press-assemble the finished fuel cell stacks, and perform insulation and airtightness tests on the pressed high-power fuel cell stacks; S2. Load the high-power fuel cell stack that has passed the insulation and airtightness tests to its maximum current limit, continuously applying high and low voltage loads to perform initial activation and polarization of the stack until the stack's internal water balance reaches an optimal state, completing initial activation and polarization. S3. According to the operating conditions, between 0.2 and 2.5A / cm 2 A value is selected within the high current density range, and the high-power fuel cell stack is controlled to set the activation load time for output operation at this value to perform constant-time high-current activation of the fuel cell stack; S4. Close the air path, maintain the hydrogen path supply, and perform a no-load shutdown purge on the high-power fuel cell stack until its output voltage drops to 0, completing one activation cycle. Step S1 further comprises: S11. The finished fuel cell stack is assembled by a press-fit process to obtain a high-power fuel cell stack after press-fitting; S12. Collect basic data before activation of the high-power stack after pressing, and record the basic data before activation; S13. Perform insulation testing on the press-assembled stack, and filter out high-power stacks whose insulation test results do not meet the standards based on the insulation parameters in the basic data before activation; S14. Further perform airtightness testing on high-power fuel cells that meet the insulation test standards. Combined with the airtightness parameters in the basic data before activation, filter out high-power fuel cells that do not meet the airtightness test standards to obtain high-power fuel cells that pass the insulation test and the airtightness test; Step S2 further comprises: S21. Determine the limiting current conditions and maximum current of the high-power stack based on the actual stack load requirements; S22. Load the high-power fuel cell stack that has passed the insulation and airtightness tests to the maximum current limit according to the above-mentioned limiting current conditions to open the mass transfer channels within the fuel cell stack, establish the gas, liquid, and fixed three-phase interface within the fuel cell stack, promote electrochemical reactions, and improve the performance of the high-power fuel cell stack; S23. Continuously applying high and low voltage loading to the high-power stack at the maximum current limit to perform initial activation and polarization of the stack and adjust the water balance within the stack; S24. During the loading process, the stack is monitored to determine whether the stack has reached an optimal water balance state, and the initial activation and polarization of the stack are terminated. Step S3 further comprises: S31. Select a value within the high current density range of 0.2 to 2.5 A / cm2 according to the operating conditions; S32. Based on the high current density selected above, a low air stoichiometric ratio is selected for air in the low stoichiometric ratio of 1 to 1.5, and a low hydrogen stoichiometric ratio is selected for hydrogen in the stoichiometric ratio of 1 to 1.5; S33. Control the high-power stack to output the selected high current density, the selected low air stoichiometric ratio and the hydrogen stoichiometric ratio as the input operation setting activation load time to perform constant time high current activation of the stack; during operation, the temperature of the hydrogen is equal to the temperature of the air, and the dew point temperature of the hydrogen is equal to the dew point temperature of the air; Step S4 further comprises: S41. Disconnect all loads on the high-power stack; S42. Close the air path, maintain the hydrogen path supply, and perform a no-load shutdown purge on the high-power stack; S43 monitors the output voltage of the high-power stack during the purge process until the output voltage drops to 0, closes the hydrogen path, executes the shutdown of the high-power stack, and completes an activation cycle; The downtime of high-power fuel cell is 10 to 25 minutes; During each activation cycle, the stack is loaded by an external load, which is a variable load.

2. The method for activating a hydrogen fuel cell stack according to claim 1, wherein: This method is applied to newly developed finished fuel cell stacks, finished fuel cell stacks in the process of research and development, or finished fuel cell stacks that have been stored for a long time after leaving the factory; and, The activation cycle is performed more than once, and the output voltage of the high-power fuel cell stack is obtained after each activation cycle, and the activation cycle is terminated until the output voltage of the high-power fuel cell stack reaches the target voltage value.

3. The method for activating a hydrogen fuel cell stack according to claim 1 or 2, wherein: For finished fuel cell stacks that have been stored for a long time after leaving the factory, steps S2 to S4 are repeated for 6 to 8 activation cycles to overcome the degradation of fuel cell performance caused by the long storage of the fuel cell stack.

4. The method for activating a hydrogen fuel cell stack according to claim 1, wherein: The basic data before activation include size, volume, mass, tooling flatness data information, press force accuracy information, press stroke information, stack free state height, height after press assembly, average shrinkage per single section, stack size, stack weight, equivalent core mass power density, equivalent core volume power density, stack dry and wet insulation parameters, stack single cavity air tightness, three cavity pressure maintaining air tightness, and leakage data information; among them, The insulation parameters in the basic data before activation include the dry and wet insulation parameters of the stack; The airtightness parameters in the basic data before activation include the stack single-cavity airtightness, three-cavity pressure-maintaining airtightness, and leakage data information; and, The insulation test includes: testing the insulation resistance between the positive electrode of the battery stack and the metal part of the battery pack shell, and the insulation resistance between the negative electrode of the battery stack and the metal part of the battery pack shell, as the actual insulation measurement data, to verify whether the actual insulation measurement data is within the insulation parameter range of the basic data before activation; The air tightness test includes: testing the single-cavity air tightness of the fuel cell stack, the three-cavity pressure-maintaining air tightness, and the leakage data respectively, and verifying whether the actual measured data of the single-cavity air tightness of the fuel cell stack, the three-cavity pressure-maintaining air tightness, and the leakage are all within the respective air tightness parameter ranges in the basic data before activation.

5. An activation device for a hydrogen fuel cell stack, characterized in that: It includes a battery stack test bench, as well as stacking pressing and testing equipment, initial activation equipment, and high current activation equipment installed on the test bench; among which, Stacking, pressing, and testing equipment, used to stack and press-assemble finished fuel cell stacks, and perform insulation and airtightness tests on the pressed high-power fuel cell stacks; and to output the high-power fuel cell stacks that have undergone insulation and airtightness tests to the initial activation equipment; Initial activation equipment is used to load the high-power fuel cell stack that has passed the insulation test and the airtightness test to the maximum current limit, and continuously perform high and low voltage loading to perform initial state activation and polarization of the fuel cell stack until it is identified that the internal water balance of the fuel cell stack has reached the optimal state. The initial state activation and polarization of the fuel cell stack are completed, and the high-power fuel cell stack is output to the high-current activation equipment; High current activation equipment, used for 0.2~2.5A / cm 2 A value is selected within the high current density range, and the high-power fuel cell stack is controlled to set the activation load time for output operation at this value to perform constant-time high-current activation of the fuel cell stack; and, after the set activation load time is reached, the air path is closed, the hydrogen path is maintained for supply, and the high-power fuel cell stack is shut down and purged in a no-load state until its output voltage drops to 0, completing an activation cycle; and, the high-power fuel cell stack is output to the initial activation equipment until it is shut down after completing the set number of activation cycles.

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