Activation method of air-cooled fuel cell stack

Abstract

The invention relates to the field of galvanic pile activation, and discloses an air-cooled fuel cell galvanic pile activation method, which comprises: based on galvanic pile design parameters, setting reaction condition parameters and control parameters of a galvanic pile, and constructing an initial reaction environment; in the initial reaction environment, carrying out a constant-current load-increasing test on the galvanic pile through a load system to obtain initial performance data of the galvanic pile; setting an activation target based on the initial performance data, and regulating reaction condition parameters and control parameters according to the activation target under a target reaction condition so as to activate the galvanic pile; and collecting performance data of the activated electric pile, comparing the performance data of the activated electric pile with preset reference data to verify an activation effect, and determining whether the activation of the electric pile is ended or not according to the activation effect. According to the activation method of the air-cooled fuel cell stack provided by the invention, the problems of long activation time, low efficiency and insufficient gas utilization rate in the existing activation method of the fuel cell stack are solved through data-driven parameter regulation and control.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell stack activation, and in particular to an activation method for an air-cooled fuel cell stack. Background Art

[0002] As an electrochemical device with an open cathode, air-cooled fuel cell stacks have the unique characteristic of using air as both an oxidant and a cooling agent. Because of this, compared to water-cooled fuel cell stacks, air-cooled fuel cell stacks experience greater fluctuations in temperature control and cathode humidity. Therefore, during the activation process, how to improve initial performance in a stable and safe manner becomes a crucial issue.

[0003] Currently, most activation methods utilize a cyclic load-variable method. However, this approach has limitations. It not only fails to fully activate the fuel cell stack, but is also costly. Furthermore, while electrochemical hydrogen pumping is a viable activation method, it requires an external power source and is relatively dangerous. Improper operation can easily cause irreversible damage to the fuel cell stack.

[0004] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an activation method for an air-cooled fuel cell stack to solve the problems of long activation time, low efficiency and insufficient gas utilization in the existing fuel cell stack activation methods.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The first aspect of the present invention provides an activation method for an air-cooled fuel cell stack, comprising: setting reaction condition parameters and control parameters of the stack based on stack design parameters to construct an initial reaction environment; the reaction condition parameters include gas flow, gas humidity, gas temperature and cathode back pressure, and the control parameters include fan voltage and current density; under the initial reaction environment, performing a constant current load test on the stack through a load system to obtain initial performance data of the stack; setting an activation target based on the initial performance data, and regulating the reaction condition parameters and control parameters according to the activation target under target reaction conditions to activate the stack; collecting performance data of the activated stack, and comparing the performance data of the activated stack with preset benchmark data to verify the activation effect, and determining whether to terminate stack activation based on the activation effect.

[0007] Optionally, in a first implementation of the first aspect of the present invention, a preset pressure is applied to the anode of the fuel cell stack and maintained for a first preset time, and whether the pressure drop of the fuel cell stack meets a preset standard is detected; if it meets the preset standard, the fuel cell stack is determined to have passed the air tightness test; if it does not meet the preset standard, the fuel cell stack is determined to have failed the air tightness test.

[0008] Optionally, in a second implementation of the first aspect of the present invention, the gas flow rate is calculated based on a preset formula, the gas humidity is adjusted by a humidifying device, the gas temperature is adjusted by a temperature control system, and the cathode back pressure is regulated by adjusting the opening of the cathode back pressure valve to set the reaction condition parameters of the fuel cell stack; the fan voltage is adjusted by a fan voltage adjustment device, and the current density is set by a load system to set the control parameters of the fuel cell stack.

[0009] Optionally, in a third implementation of the first aspect of the present invention, the gas flow rate is calculated using the following formula based on the operating current of the fuel cell stack, the number of fuel cell stack cells, and the reaction gas pressure, combined with the hydrogen stoichiometric ratio, gas constant, Kelvin temperature, Faraday constant, and gas molar volume correction factor: ; Wherein, Q is the gas flow rate, I is the operating current, b is the hydrogen stoichiometric ratio, N is the number of single cells in the fuel cell stack, R is the gas constant, K is the Kelvin temperature, P is the reaction gas pressure, F is the Faraday constant, and a is the gas molar volume correction factor.

[0010] Optionally, in a fourth implementation of the first aspect of the present invention, the output current of the fuel cell stack is increased with a fixed current through a load system according to a first preset interval time, and the single-cell voltage value, average voltage value and polarization curve of the output current are recorded; based on the single-cell voltage value, average voltage value and polarization curve, the initial performance data of the fuel cell stack is formed.

[0011] Optionally, in a fifth implementation of the first aspect of the present invention, the single-cell voltage value, average voltage value and polarization curve of the initial performance data are extracted; a voltage uniformity target is set based on the maximum difference in the distribution of the single-cell voltage values; a performance optimization target is set based on the difference between the average voltage value and the rated voltage of the fuel cell stack; a mass transfer optimization target is set based on the voltage attenuation rate in the low current density interval of the polarization curve; and an activation target is formed based on the voltage uniformity target, the performance optimization target and the mass transfer optimization target.

[0012] Optionally, in a sixth implementation of the first aspect of the present invention, when the maximum difference in the distribution of single-section voltage values ​​is greater than a first preset difference, it is determined that the voltage uniformity target of the fuel cell stack is not met, and the fan voltage is reduced to 0V to create an oxygen-deficient environment and maintained until a second preset time; when the difference between the average voltage value and the rated voltage of the fuel cell stack is greater than a second preset difference, it is determined that the performance optimization target of the fuel cell stack is not met, and the gas humidity is increased or the cathode back pressure is reduced; when the voltage decay rate in the low current density range is greater than a third preset difference, it is determined that the mass transfer efficiency target of the fuel cell stack is not met, and the current density is adjusted to a low current range.

[0013] Optionally, in a seventh implementation of the first aspect of the present invention, the single-cell voltage value, average voltage value and polarization curve of the activated fuel cell stack are collected; the single-cell voltage difference is compared with a preset uniformity threshold, the average voltage value is compared with the deviation of the designed rated voltage, and the polarization curve attenuation rate is compared with a preset mass transfer efficiency threshold to obtain a comparison result; based on the comparison result, when it is determined that the single-cell voltage difference, average voltage value and polarization curve attenuation rate all meet the corresponding indicators, the activation effect is judged to be up to standard; based on the comparison result, when it is determined that any indicator of the single-cell voltage difference, average voltage value or polarization curve attenuation rate is not met, the activation effect is judged to be unsatisfactory.

[0014] Optionally, in an eighth implementation of the first aspect of the present invention, when it is determined based on the activation effect that the activation effect meets the standard, the activation of the fuel cell stack is terminated and the performance data of the fuel cell stack is saved; when it is determined based on the activation effect that the activation effect does not meet the standard, based on the deviation between the non-standard performance data of the fuel cell stack and the activation target, the reaction condition parameters and control parameters are regulated under the target reaction conditions.

[0015] Optionally, in a ninth implementation of the first aspect of the present invention, based on the stack design parameters, the reaction condition parameters and control parameters of the activated stack are set so that the reaction condition parameters and control parameters are consistent with the parameters under the initial reaction environment; according to a second preset interval time, the stack output current is increased with a fixed current through the load system, and the single-cell voltage value, average voltage value and polarization curve of the output current are recorded; based on the single-cell voltage value, average voltage value and polarization curve, a performance acceptance report is generated including the maximum difference in single-cell voltage, average voltage stability and polarization curve comparison diagram, and the performance acceptance report serves as the final verification basis for the stack activation effect.

[0016] Beneficial effects: In the technical solution of the present invention, reaction condition parameters such as gas flow, humidity, temperature, cathode back pressure, and control parameters such as fan voltage and current density are set based on the design parameters of the fuel cell stack to construct an initial reaction environment; a constant current load test is performed on the fuel cell stack through a load system to obtain initial performance data such as single-cell voltage value, average voltage value and polarization curve; activation targets such as voltage uniformity, performance optimization and mass transfer optimization are set based on the initial performance data, and activation is carried out according to target control parameters under target reaction conditions; finally, the performance data of the fuel cell stack after activation is collected, and the effect is compared with the preset benchmark to verify the effect, and decide whether to end the activation. The present invention forms a closed-loop process of data collection-target setting-parameter optimization-effect verification through data-driven parameter precision control, which effectively solves the problems of long activation time, low efficiency and insufficient gas utilization in existing activation methods. It is simple to operate, takes less time, consumes less hydrogen, and can be carried out in a low current environment without causing irreversible damage to the fuel cell stack, significantly improving the fuel cell stack performance and overall output capacity, and reducing the activation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A first flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 2 A second flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 3 A third flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 4 A fourth flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 5 A fifth flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 6 A sixth flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 7 A seventh flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 8 This is an eighth flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention; Figure 9 A ninth flow chart of the method for activating an air-cooled fuel cell stack provided by the present invention; Figure 10 This is the tenth flow chart of the activation method for an air-cooled fuel cell stack provided by the present invention. DETAILED DESCRIPTION

[0018] The embodiment of the present invention provides an activation method for an air-cooled fuel cell stack. Based on the stack design parameters, reaction condition parameters such as gas flow, humidity, temperature, cathode back pressure, and control parameters such as fan voltage and current density are set to construct an initial reaction environment; a constant current load test is performed on the stack through a load system to obtain initial performance data such as single-cell voltage value, average voltage value, and polarization curve; activation targets such as voltage uniformity, performance optimization, and mass transfer optimization are set based on the initial performance data, and activation is carried out according to target control parameters under target reaction conditions; finally, the performance data of the activated stack is collected, and the effect is compared with a preset benchmark to verify the effect and decide whether to end the activation. The present invention provides an activation method for an air-cooled fuel cell stack, which is based on a cathode oxygen deficiency activation method. The stack activation operation is simple, time-saving, and low in hydrogen consumption. It can also be carried out in a low-current environment without causing irreversible damage to the stack. More importantly, after activation by this method, the performance of the stack is significantly improved.

[0019] The terms "first," "second," "third," "fourth," and so on (if any) in the description and claims of the present invention and in the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that shown or described herein. In addition, the terms "including" or "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product, or apparatus.

[0020] For ease of understanding, the specific process of the embodiment of the present invention is described below. Figure 1 The first embodiment of the activation method of the air-cooled fuel cell stack in the embodiment of the present invention includes: S100, based on the stack design parameters, setting the reaction condition parameters and control parameters of the stack to establish an initial reaction environment; the reaction condition parameters include gas flow, gas humidity, gas temperature, and cathode back pressure; the control parameters include fan voltage and current density; In this embodiment, when performing stack activation, the following are required: a test bench including a hydrogen inlet, a hydrogen outlet, a deionized water inlet and outlet, and an air inlet and outlet; an electronic load for connecting the positive and negative poles of the stack and controlling the output current; an inspection and monitoring device for recording the voltage of a single cell of the stack in real time; a DC regulated power supply for adjusting the fan voltage; a humidifying device for adjusting the gas humidity; a temperature control system for adjusting the gas temperature; and a back pressure regulating valve for regulating the cathode back pressure.

[0021] In actual application, first connect the anode inlet of the air-cooled fuel cell stack to the hydrogen inlet of the test bench, and connect the anode outlet to the hydrogen outlet of the test bench; short-circuit the deionized water inlet and outlet of the test bench and the air inlet and outlet; connect the positive and negative poles of the fuel cell stack to the positive and negative poles of the electronic load, and connect the fuel cell stack to the inspection and monitoring device to collect single-cell voltage data in real time; connect the power interface of the fan to the DC regulated power supply to adjust the fan voltage; the humidification device, temperature control system and back pressure regulating valve are respectively connected to the parameter control module of the test bench, and automatic adjustment is achieved through the system software.

[0022] As an example, a DC regulated power supply is used to set the fan voltage to 48V, followed by nitrogen wetting of the MEA. In this case, the gas is nitrogen, and the nitrogen flow rate, nitrogen humidity, nitrogen temperature, and nitrogen cathode backpressure must be configured. Specifically, the nitrogen flow rate is calculated based on a preset formula, the nitrogen humidity is set to 50% RH via the humidifier, the nitrogen temperature is set to 60°C via the temperature control system, and the nitrogen cathode backpressure is set to 20 kPa via the backpressure regulating valve. The process is run for 5-10 minutes to complete membrane electrode wetting. After the membrane electrode wetting process is complete, hydrogen is switched to prepare for activation. When using hydrogen as the gas, the hydrogen flow rate, hydrogen humidity, hydrogen temperature, and hydrogen cathode backpressure must be configured. Specifically, the hydrogen flow rate is calculated based on a preset formula, the hydrogen humidity is set to 50% RH via the humidifier, the hydrogen temperature is set to 60°C via the temperature control system, the hydrogen cathode backpressure is set to 50 kPa via the backpressure regulating valve, and the initial current density is set to 0 A / cm² via the load system. Ensure that the ambient temperature is room temperature (23°C~27°C) and the ambient humidity is 50% to 90% to meet the initial reaction conditions of the stack. Among them, the room temperature is set to 25 degrees Celsius + 2 degrees Celsius in this embodiment, that is, the ambient temperature needs to be maintained in the range of 23°C~27°C, which is the optimal operating environment temperature for air-cooled stacks, and can avoid temperature fluctuations from interfering with the stack performance test. It should be understood that the gas is nitrogen or hydrogen. Nitrogen is used for membrane electrode wetting in the pretreatment stage and belongs to the pretreatment sub-environment of the initial environment; while hydrogen, as the reaction fuel of the fuel cell, can activate the active sites of the catalytic layer through electrochemical reactions to achieve the improvement of the stack performance, and belongs to the core sub-environment of the initial environment. The two together constitute the initial reaction environment to ensure the stability and effectiveness of the activation process.

[0023] S200, performing a constant current load-increasing test on the fuel cell stack through a load system under the initial reaction environment to obtain initial performance data of the fuel cell stack; In this example, under a constructed initial reaction environment, the stack was gradually loaded with an electronic load, simulating the current changes during actual operation. Data such as the stack's voltage and polarization curves at different currents were simultaneously collected to generate initial performance data. This stable load-increasing process allowed the stack to demonstrate its baseline performance before activation, providing a basis for setting subsequent activation targets.

[0024] As an example, the load-up process uses a current interval of 1A, and the stack output current is increased at a constant current interval of 10 to 30 seconds until the average voltage reaches 0.45V to 0.5V and runs in this range for more than 1 minute, at which time the load-up is stopped. During the load-up process, the single-cell voltage value, average voltage value, and polarization curve of each battery are recorded by the inspection and monitoring device to form initial performance data including voltage distribution, average voltage, and polarization curve. When de-loading, the voltage is reduced to the open-circuit voltage at intervals of 1A to avoid long-term low-current operation causing stack performance degradation.

[0025] S300, setting an activation target based on the initial performance data, and regulating the reaction condition parameters and control parameters according to the activation target under target reaction conditions to activate the fuel cell stack; In this example, based on initial performance data, key indicators reflecting stack uniformity, performance deviation, and mass transfer efficiency, such as single-cell voltage difference, average voltage value, and polarization curve decay rate, are extracted to set activation targets. By adjusting reaction conditions such as hydrogen humidity and cathode backpressure, and control parameters such as fan voltage and current density, stack performance is optimized until the target is achieved. This example represents the core control step in activation, addressing initial stack performance deficiencies through dynamic parameter adjustment.

[0026] As an example, the indicators extracted from the initial data are: maximum single-cell voltage difference of 8mV (target less than or equal to 5mV), average voltage value of 4% (target less than or equal to 3%), and polarization curve decay rate of 0.4 volts per ampere per square centimeter (target less than or equal to 0.3 volts per ampere per square centimeter). Since the single-cell voltage difference of 8mV is greater than 5mV, the single-cell voltage difference is too large, so the fan voltage is reduced from 48V to 0V, the cathode fan is turned off, and an oxygen-deficient environment is created and maintained for 5 seconds, forcing the single-cell battery with too high voltage to reduce the reaction rate due to lack of oxygen, thereby reducing the inter-cell voltage difference; since the average voltage value of 4% is greater than 3%, the average voltage value is too large, so the hydrogen humidity is increased from 50%RH to 60%RH, the membrane electrode water content is increased, and the proton conductivity is improved. At the same time, the cathode back pressure is reduced from 50kPa to 40kPa, the gas pressure is reduced, and the cathode mass transfer resistance is reduced; since the polarization curve attenuation rate of 0.4V is greater than 0.3V, the current density is adjusted from 0.2 amperes per square centimeter to the low current range of 0.05 amperes per square centimeter, and the residence time at each current point is extended to 40 seconds to promote full activation of the active sites of the catalytic layer.

[0027] Repeat the above control steps until the single-cell voltage difference drops to 5mV, the average voltage value drops to 3%, and the attenuation rate drops to 0.3 volts per ampere per square centimeter, meeting the target requirements, so as to activate the battery stack.

[0028] S400 , collecting performance data of the activated fuel cell stack, and comparing the performance data of the activated fuel cell stack with preset benchmark data to verify activation effect, and determining whether to terminate fuel cell stack activation based on the activation effect.

[0029] In this embodiment, after the activation of the battery stack is completed, the performance data of the battery stack, such as the single-cell voltage, average voltage, and polarization curve, are collected again and compared with the preset benchmark data, such as the single-cell voltage difference is less than or equal to 5mV, the average voltage value is less than or equal to 3%, and the attenuation rate is less than or equal to 0.3 volts per ampere per square centimeter, to determine whether the activation is successful. If the standard is met, the activation is terminated; if the standard is not met, the control is returned to S300 and repeated; if the standard is still not met after multiple controls, the battery stack is determined to be unqualified. This embodiment is a closed-loop verification link in the activation process to ensure that the performance of the battery stack meets the design requirements.

[0030] For example, the performance data collected after activation includes: a single-cell voltage difference of 3mV (target ≤5mV), an average voltage of 1% (target ≤3%), and a polarization curve decay rate of 0.25 volts per ampere per square centimeter (target ≤0.3 volts per ampere per square centimeter). These all meet the benchmark requirements, so activation is terminated and the data saved. If the single-cell voltage difference is still greater than 6mV after a given activation cycle, the system returns to S300 and repeats the hypoxic environment control. If the standard is still not met after 10 consecutive cycles, such as if the single-cell voltage difference remains greater than 5mV, the activation process is terminated, the stack is marked as defective, and the fault analysis phase begins.

[0031] This embodiment provides an activation method for an air-cooled fuel cell stack, which aims to solve the technical problems of insufficient activation and excessively long activation time of an air-cooled fuel cell stack, improve the activation efficiency of the air-cooled fuel cell stack, fully activate each cell in the stack, and improve the overall output performance of the stack.

[0032] See also Figure 2 The second embodiment of the activation method of the air-cooled fuel cell stack in the embodiment of the present invention includes: S510, applying a preset pressure to the anode of the fuel cell stack and maintaining it for a first preset time, and detecting whether the pressure drop of the fuel cell stack meets a preset standard; S520: If the preset standard is met, the stack is determined to have passed the airtightness test; S530: If the preset standard is not met, the fuel cell stack is determined to have failed the airtightness test.

[0033] In this embodiment, before establishing the initial reaction environment, the stack is first tested for leaks: a preset pressure of 50 kPa is applied to the anode of the stack and maintained for a first preset time of 10 minutes. The pressure drop is then checked to see if it does not exceed a preset standard of 30 kPa. For example, if the pressure drops to 20 kPa after 10 minutes, the test is considered passed; if the pressure drops to 40 kPa, the test is considered failed and leaks must be identified and retested.

[0034] See also Figure 3 The third embodiment of the method for activating an air-cooled fuel cell stack according to the present invention includes: S110, calculating the gas flow rate based on a preset formula, adjusting the gas humidity through a humidifier, adjusting the gas temperature through a temperature control system, and regulating the cathode back pressure by adjusting the opening of a cathode back pressure valve to set reaction condition parameters of the fuel cell stack; S120 , regulating the fan voltage through a fan voltage regulating device, and setting the current density through a load system to set control parameters of the fuel cell stack.

[0035] In this embodiment, the gas is either nitrogen or hydrogen. When nitrogen is used, it is used to wet the membrane electrode during the preconditioning phase and constitutes the preconditioning subenvironment of the initial environment. When hydrogen is used, it serves as the fuel cell's reaction fuel, activating the active sites in the catalytic layer through electrochemical reactions, thereby improving stack performance and constituting the core subenvironment of the initial environment. Together, these two gases constitute the initial reaction environment, ensuring the stability and effectiveness of the activation process. Therefore, the MEA is first wetted with nitrogen to complete the membrane electrode wetting operation. After this is complete, hydrogen is switched to prepare for activation. The term "MEA" in the wetting operation refers to the membrane electrode assembly (MEA) in the fuel cell. The MEA is a core component of the fuel cell, providing microchannels for multiphase mass transfer and a site for electrochemical reactions. During the wetting operation, the MEA's proton exchange membrane must be wetted with water to ensure proper electrolyte function. If the MEA is not fully wetted, the cell may not immediately output current and voltage when the methanol solution is introduced. Fuel cell performance is only apparent after water diffuses through the membrane and fully wets it.

[0036] In actual application, the fan voltage is set to 48V via a DC regulated power supply, followed by nitrogen wetting of the MEA. In this case, nitrogen is used as the gas, and the nitrogen flow rate, nitrogen humidity, nitrogen temperature, and nitrogen cathode backpressure must be set. Specifically, the nitrogen flow rate is calculated based on a preset formula, the nitrogen humidity is set to 50% RH via the humidifier, the nitrogen temperature is set to 60°C via the temperature control system, and the nitrogen cathode backpressure is set to 20 kPa via the backpressure regulating valve. The process is run for 5-10 minutes to complete membrane electrode wetting. After the membrane electrode wetting process is complete, hydrogen is switched to prepare for activation. When using hydrogen as the gas, the hydrogen flow rate, hydrogen humidity, hydrogen temperature, and hydrogen cathode backpressure must be set. Specifically, the hydrogen flow rate is calculated based on a preset formula, the hydrogen humidity is set to 50% RH via the humidifier, the hydrogen temperature is set to 60°C via the temperature control system, the hydrogen cathode backpressure is set to 50 kPa via the backpressure regulating valve, and the initial current density is set to 0 A / cm² via the load system. Ensure that the ambient temperature is room temperature (23°C to 27°C) and the humidity is between 50% and 90% to meet the initial reaction conditions for the stack. In this embodiment, the room temperature is set at 25°C ± 2°C, meaning the ambient temperature must be maintained within the range of 23°C to 27°C, the optimal operating temperature for air-cooled stacks. This range prevents temperature fluctuations from interfering with stack performance testing. Thus, the above membrane electrode wetting and activation preparations together create the initial reaction environment, ensuring the stability and effectiveness of the activation process.

[0037] See also Figure 4 The fourth embodiment of the activation method of the air-cooled fuel cell stack in the embodiment of the present invention includes: S111. Based on the operating current of the fuel cell stack, the number of fuel cell cells, and the reaction gas pressure, combined with the hydrogen stoichiometric ratio, gas constant, Kelvin temperature, Faraday constant, and gas molar volume correction factor, calculate the gas flow rate using the following formula: ; Wherein, Q is the gas flow rate, I is the operating current, b is the hydrogen stoichiometric ratio, N is the number of single cells in the fuel cell stack, R is the gas constant, K is the Kelvin temperature, P is the reaction gas pressure, F is the Faraday constant, and a is the gas molar volume correction factor.

[0038] In this embodiment, the gas flow rate is calculated based on the operating current of the fuel cell stack, the number of fuel cell stack cells and the reaction gas pressure, and the formula is: gas flow rate Q = (operating current I × hydrogen stoichiometric ratio b × number of single cells in the fuel cell stack N × gas constant R × Kelvin temperature K × 1000 × 60) ÷ (reaction gas pressure P × Faraday constant F × gas molar volume correction factor a).

[0039] As an example, when calculating the nitrogen flow rate (nitrogen wetting MEA operation): take the operating current I=10A, the hydrogen stoichiometric ratio b=1.0, the number of single-cell stack N=50, the gas constant R=8.314, the Kelvin temperature K=333K, the reaction gas pressure P=20kPa, the Faraday constant F=96485, and the gas molar volume correction factor a=2, and substitute them into the formula to calculate the nitrogen flow rate to be 173SLPM; when calculating the hydrogen flow rate (activation preparation): take the operating current I=10A, the hydrogen stoichiometric ratio b=0.8, the number of single-cell stack N=50, the gas constant R=8.314, the Kelvin temperature K=333K, the reaction gas pressure P=50kPa, the Faraday constant F=96485, and the gas molar volume correction factor a=2, and substitute them into the formula to calculate the hydrogen flow rate to be 69SLPM. Due to the difference in reaction gas pressure P and hydrogen stoichiometric ratio b, the nitrogen flow rate (173 SLPM) is approximately 2.5 times the hydrogen flow rate (69 SLPM).

[0040] It's important to understand that calculating gas flow rates includes both nitrogen and hydrogen flow rates. The nitrogen flow rate is calculated to provide a stable humidification environment for the membrane electrode (MEA). A nitrogen flow rate of 173 SLPM at 50% humidity allows for sufficient moisture absorption by the proton exchange membrane, improving ionic conductivity. A higher flow rate (with a lower back pressure of 20 kPa) ensures uniform moisture distribution and prevents localized drying. The hydrogen flow rate is calculated to ensure sufficient fuel supply for the electrochemical reaction. A hydrogen flow rate of 69 SLPM (with a higher back pressure of 50 kPa) maintains reaction efficiency at a current of 10-15 A. Furthermore, by matching the flow rate to the current (e.g., 10 A corresponds to approximately 69 SLPM), the hydrogen stoichiometric ratio (b=0.8) is maintained, avoiding performance degradation caused by fuel waste or insufficient supply. In summary, using the same formula, varying gas flow rates due to parameters such as current and back pressure can meet the requirements of the nitrogen humidification and activation preparation stages.

[0041] See also Figure 5 The fifth embodiment of the method for activating an air-cooled fuel cell stack in the embodiment of the present invention includes: S210, increasing the stack output current with a fixed current through a load system at a first preset interval, and recording a single-cell voltage value, an average voltage value, and a polarization curve of the output current; S220 , forming initial performance data of the fuel cell stack based on the single-cell voltage value, average voltage value, and polarization curve.

[0042] In this embodiment, the first preset interval time is set to 10-30 seconds, and the fixed current is 1A. In actual applications, according to the first preset interval time of 10-30 seconds, the output current of the battery stack is increased by the load system with a fixed current of 1A. As an example, starting from 0A, 1A is increased every 20 seconds until the average voltage of the battery stack reaches 0.45-0.5V and maintained for more than 1 minute, and the single-cell voltage value of each current point is recorded, such as the voltage of 20 batteries is 0.52V, 0.51V...0.48V, the average voltage value is such as 0.50V and the polarization curve, and the single-cell voltage value, the average voltage value and the polarization curve form the initial performance data. When reducing the load, it is quickly reduced to the open circuit voltage at an interval of 1A, and each current point stays for less than 2 seconds.

[0043] See also Figure 6 The sixth embodiment of the method for activating an air-cooled fuel cell stack in the present invention includes: S310, extracting a single-cell voltage value, an average voltage value, and a polarization curve of the initial performance data; S320: Setting a voltage uniformity target based on the maximum difference in the single-cell voltage distribution; setting a performance optimization target based on the difference between the average voltage value and the rated voltage of the stack; and setting a mass transfer optimization target based on the voltage decay rate in the low current density range of the polarization curve. S330: Based on the voltage uniformity target, the performance optimization target, and the mass transfer optimization target, an activation target is formed.

[0044] In this embodiment, based on the initial performance data, key indicators reflecting the uniformity, performance deviation, and mass transfer efficiency of the stack are extracted, such as the single-cell voltage difference, average voltage value, and polarization curve decay rate, to set activation targets. For example, if the maximum single-cell voltage difference is 8mV, the voltage uniformity target is set to less than or equal to 5mV; if the average voltage value of 0.48V deviates from the rated voltage of 0.5V by 4%, the performance optimization target is set to less than or equal to 3%; if the polarization curve decay rate is 0.4 volts per ampere per square centimeter, the mass transfer optimization target is set to less than or equal to 0.3 volts per ampere per square centimeter.

[0045] See also Figure 7 The seventh embodiment of the method for activating an air-cooled fuel cell stack in the embodiment of the present invention includes: S340: When the maximum difference of the single-cell voltage value distribution is greater than a first preset difference, determining that the voltage uniformity target of the fuel cell stack is not met, reducing the fan voltage to 0V to create an oxygen-deficient environment, and maintaining the environment for a second preset time; S350: When the difference between the average voltage value and the rated voltage of the fuel cell stack is greater than a second preset difference, determine that the performance optimization target of the fuel cell stack is not met, and increase the gas humidity or reduce the cathode back pressure; S360: When the voltage decay rate in the low current density range is greater than a third preset difference, it is determined that the mass transfer efficiency target of the fuel cell stack is not met, and the current density is adjusted to a low current range.

[0046] In this embodiment, by adjusting reaction condition parameters such as hydrogen humidity, cathode back pressure and control parameters such as fan voltage and current density, the performance of the fuel cell stack is optimized in a targeted manner until the target is achieved, so as to dynamically adjust parameters to solve the initial performance defects of the fuel cell stack.

[0047] As an example, the indicators extracted from the initial data are: maximum single-cell voltage difference of 8mV (target less than or equal to 5mV), average voltage value of 4% (target less than or equal to 3%), and polarization curve decay rate of 0.4 volts per ampere per square centimeter (target less than or equal to 0.3 volts per ampere per square centimeter). Since the single-cell voltage difference of 8mV is greater than 5mV, the single-cell voltage difference is too large, so the fan voltage is reduced from 48V to 0V, the cathode fan is turned off, and an oxygen-deficient environment is created and maintained for 5 seconds, forcing the single-cell battery with too high voltage to reduce the reaction rate due to lack of oxygen, thereby reducing the inter-cell voltage difference; since the average voltage value of 4% is greater than 3%, the average voltage value is too large, so the hydrogen humidity is increased from 50%RH to 60%RH, the membrane electrode water content is increased, and the proton conductivity is improved. At the same time, the cathode back pressure is reduced from 50kPa to 40kPa, the gas pressure is reduced, and the cathode mass transfer resistance is reduced; since the polarization curve attenuation rate of 0.4V is greater than 0.3V, the current density is adjusted from 0.2 amperes per square centimeter to the low current range of 0.05 amperes per square centimeter, and the residence time at each current point is extended to 40 seconds to promote full activation of the active sites of the catalytic layer.

[0048] See also Figure 8 The eighth embodiment of the method for activating an air-cooled fuel cell stack in the embodiment of the present invention includes: S410, collecting the single-cell voltage value, average voltage value and polarization curve of the activated stack; S420, comparing the single-cell voltage difference with a preset uniformity threshold, comparing the average voltage value with a deviation from a designed rated voltage, and comparing the polarization curve attenuation rate with a preset mass transfer efficiency threshold to obtain a comparison result; S430: When it is determined based on the comparison result that the single-cell voltage difference, the average voltage value, and the polarization curve decay rate all meet corresponding indicators, it is determined that the activation effect meets the standard; S440: When it is determined based on the comparison result that any one of the single-cell voltage difference, average voltage value, or polarization curve decay rate is not satisfied, it is determined that the activation effect does not meet the standard.

[0049] In this embodiment, after the activation of the battery stack is completed, the performance data of the battery stack, such as the single-cell voltage, average voltage, and polarization curve, are re-collected and compared with the preset benchmark data, such as the single-cell voltage difference is less than or equal to 5mV, the average voltage value is less than or equal to 3%, and the attenuation rate is less than or equal to 0.3 volts per ampere per square centimeter, to determine whether the activation is successful.

[0050] For example, performance data collected after activation includes: a single-cell voltage difference of 3mV (target ≤5mV), an average voltage value of 1% (target ≤3%), and a polarization curve decay rate of 0.25 volts per ampere per square centimeter (target ≤0.3 volts per ampere per square centimeter). If all of these meet the benchmark requirements, the activation is considered satisfactory. If the single-cell voltage difference after a given activation is still greater than 6mV (>5mV), the activation is considered substandard.

[0051] See also Figure 9 The ninth embodiment of the method for activating an air-cooled fuel cell stack according to the present invention includes: S450, when it is determined that the activation effect meets the standard according to the activation effect, ending the activation of the fuel cell stack and saving the performance data of the fuel cell stack; S460: When it is determined that the activation effect does not meet the standard according to the activation effect, the reaction condition parameters and the control parameters are adjusted under the target reaction conditions based on the deviation between the non-standard performance data of the fuel cell stack and the activation target.

[0052] In this embodiment, if the activation effect meets the target, activation is terminated. If not, control is continued based on the deviation between the non-target data and the activation target. If the target is still not met after multiple control attempts, the stack is deemed unqualified. This embodiment forms a closed-loop verification step in the activation process, ensuring that the stack performance meets design requirements.

[0053] As an example, the performance data collected after activation includes: a single-cell voltage difference of 3mV (target ≤5mV), an average voltage of 1% (target ≤3%), and a polarization curve decay rate of 0.25 volts per ampere per square centimeter (target ≤0.3 volts per ampere per square centimeter). All of these meet the benchmark requirements, so activation is terminated and the data is saved. If the single-cell voltage difference is still greater than 6mV after a given activation, the hypoxic environment control is repeated. If the standard is still not met after 10 consecutive control cycles, such as if the single-cell voltage difference is consistently greater than 5mV, the activation process is terminated, the stack is marked as defective, and the fault analysis phase begins.

[0054] See also Figure 10 The tenth embodiment of the method for activating an air-cooled fuel cell stack in the embodiments of the present invention includes: S610, setting reaction condition parameters and control parameters of the activated stack based on the stack design parameters, so that the reaction condition parameters and control parameters are consistent with the parameters under the initial reaction environment; S620: Boost the stack output current with a fixed current through a load system at a second preset interval, and record a single-cell voltage value, an average voltage value, and a polarization curve of the output current; S630. Based on the single-cell voltage value, average voltage value and polarization curve, generate a performance acceptance report including the single-cell voltage maximum difference, average voltage stability and polarization curve comparison chart. The performance acceptance report serves as the final verification basis for the activation effect of the fuel cell stack.

[0055] In this example, after stack activation is complete, reaction conditions (e.g., hydrogen flow rate corresponding to 10-15A, humidity 50% RH, temperature 60°C, back pressure 50kPa) and control parameters (e.g., fan voltage 48V, current density 0 amperes per square centimeter) are restored to their initial state. The load is increased in 1A increments, running for 1 minute at each point until the average voltage reaches 0.5-0.6V. The individual cell voltage, average voltage, and polarization curve are recorded. A performance acceptance report is generated, including the maximum individual cell voltage difference (e.g., 3mV), average voltage stability (e.g., fluctuation less than or equal to 2%), and polarization curve comparison charts, serving as the final verification of activation effectiveness.

[0056] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for activating an air-cooled fuel cell stack, characterized in that: The activation method of the air-cooled fuel cell stack comprises: Based on the stack design parameters, setting the reaction condition parameters and control parameters of the stack to build an initial reaction environment; the reaction condition parameters include gas flow, gas humidity, gas temperature and cathode back pressure, and the control parameters include fan voltage and current density; Under the initial reaction environment, performing a constant current load-increasing test on the fuel cell stack through a load system to obtain initial performance data of the fuel cell stack; setting an activation target based on the initial performance data, and regulating the reaction condition parameters and control parameters according to the activation target under target reaction conditions to activate the fuel cell stack; The performance data of the activated stack is collected, and the performance data of the activated stack is compared with preset benchmark data to verify the activation effect, and whether to terminate the stack activation is determined based on the activation effect.

2. The method for activating an air-cooled fuel cell stack according to claim 1, wherein: Before the step of constructing the initial reaction environment, the method further includes: Applying a preset pressure to the anode of the fuel cell stack and maintaining it for a first preset time, and detecting whether the pressure drop of the fuel cell stack meets a preset standard; If it meets the preset standards, the stack is judged to have passed the airtightness test; If the preset standards are not met, the fuel cell stack is determined to have failed the airtightness test.

3. The method for activating an air-cooled fuel cell stack according to claim 1, wherein: The step of setting the reaction condition parameters and control parameters of the fuel cell stack includes: Calculating the gas flow rate based on a preset formula, adjusting the gas humidity through a humidifier, adjusting the gas temperature through a temperature control system, and regulating the cathode back pressure by adjusting the opening of a cathode back pressure valve to set reaction condition parameters of the fuel cell stack; The fan voltage is adjusted by a fan voltage adjustment device, and the current density is set by a load system to set the control parameters of the fuel cell stack.

4. The method for activating an air-cooled fuel cell stack according to claim 3, wherein: The step of calculating the gas flow rate based on a preset formula includes: Based on the operating current of the fuel cell stack, the number of fuel cell cells, and the reaction gas pressure, combined with the hydrogen stoichiometric ratio, gas constant, Kelvin temperature, Faraday constant, and gas molar volume correction factor, the gas flow rate is calculated using the following formula: ； Wherein, Q is the gas flow rate, I is the operating current, b is the hydrogen stoichiometric ratio, N is the number of single cells in the fuel cell stack, R is the gas constant, K is the Kelvin temperature, P is the reaction gas pressure, F is the Faraday constant, and a is the gas molar volume correction factor.

5. The method for activating an air-cooled fuel cell stack according to claim 1, wherein: The step of performing a constant current load-increasing test on the fuel cell stack through a load system to obtain initial performance data of the fuel cell stack includes: At a first preset interval, the stack output current is increased by a load system at a fixed current, and a single-cell voltage value, an average voltage value, and a polarization curve of the output current are recorded; Based on the single-cell voltage value, average voltage value and polarization curve, initial performance data of the fuel cell stack is formed.

6. The method for activating an air-cooled fuel cell stack according to claim 1, wherein: The step of setting an activation target based on the initial performance data comprises: Extracting a single-cell voltage value, an average voltage value, and a polarization curve of the initial performance data; A voltage uniformity target is set based on the maximum difference in the distribution of single-cell voltage values; a performance optimization target is set based on the difference between the average voltage value and the rated voltage of the stack; and a mass transfer optimization target is set based on the voltage decay rate in the low current density interval of the polarization curve; Based on the voltage uniformity target, performance optimization target and mass transfer optimization target, an activation target is formed.

7. The method for activating an air-cooled fuel cell stack according to claim 6, wherein: The step of regulating the reaction condition parameters and the control parameters according to the activation target under the target reaction conditions comprises: When the maximum difference of the single-cell voltage value distribution is greater than a first preset difference, determining that the voltage uniformity target of the fuel cell stack has not been met, reducing the fan voltage to 0V to create an oxygen-deficient environment, and maintaining it for a second preset time; When the difference between the average voltage value and the rated voltage of the fuel cell stack is greater than a second preset difference, determining that the performance optimization target of the fuel cell stack is not met, increasing the gas humidity or reducing the cathode back pressure; When the voltage decay rate in the low current density range is greater than a third preset difference, it is determined that the mass transfer efficiency target of the fuel cell stack has not been met, and the current density is adjusted to a low current range.

8. The method for activating an air-cooled fuel cell stack according to claim 1, wherein: The step of collecting performance data of the activated stack and comparing the performance data of the activated stack with preset benchmark data to verify the activation effect includes: Collect the single-cell voltage value, average voltage value and polarization curve of the activated stack; Comparing the single-node voltage difference with a preset uniformity threshold, comparing the average voltage value with a deviation from a designed rated voltage, and comparing the polarization curve attenuation rate with a preset mass transfer efficiency threshold to obtain a comparison result; When, based on the comparison results, it is determined that the single-cell voltage difference, the average voltage value, and the polarization curve decay rate all meet corresponding indicators, it is determined that the activation effect meets the standards; When it is determined based on the comparison result that any one of the single-cell voltage difference, the average voltage value, or the polarization curve decay rate is not satisfied, it is determined that the activation effect does not meet the standard.

9. The method for activating an air-cooled fuel cell stack according to claim 1, wherein: The step of determining whether to terminate stack activation based on the activation effect includes: When it is determined that the activation effect meets the standard according to the activation effect, the activation of the fuel cell stack is terminated and the performance data of the fuel cell stack is saved; When it is determined that the activation effect does not meet the standard according to the activation effect, the reaction condition parameters and the control parameters are adjusted under the target reaction conditions based on the deviation of the non-standard performance data of the fuel cell stack and the activation target.

10. The method for activating an air-cooled fuel cell stack according to claim 9, wherein: After the step of completing the stack activation, the method further includes: Based on the stack design parameters, setting reaction condition parameters and control parameters of the activated stack so that the reaction condition parameters and control parameters are consistent with the parameters under the initial reaction environment; At a second preset interval, the stack output current is increased by a load system at a fixed current, and a single-cell voltage value, an average voltage value, and a polarization curve of the output current are recorded; Based on the single-cell voltage value, average voltage value and polarization curve, a performance acceptance report including the single-cell voltage maximum difference, average voltage stability and polarization curve comparison chart is generated. The performance acceptance report serves as the final verification basis for the activation effect of the fuel cell stack.

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