Accelerated stress test method based on proton exchange membrane (PEM) electrolytic cell

Abstract

The invention discloses an accelerated stress testing method based on a proton exchange membrane (PEM) electrolytic cell. Relates to the technical field of electrochemical testing. The method comprises the following steps: applying cyclically changing dynamic electric load stress to a proton exchange membrane electrolytic cell; in the stress applying process, transient diagnosis is synchronously executed to obtain electrochemical parameters; the electrochemical parameters are evaluated in real time, when the electrochemical parameters meet preset health state triggering conditions, the dynamic stress is interrupted, and a recovery protocol is automatically triggered and executed; and after the recovery protocol is executed, the transient diagnosis is executed again to evaluate the recovery effect. According to the method, self-adaptive closed-loop control based on real-time diagnosis results is introduced, so that the technical problems that an existing accelerated stress test method cannot evaluate a performance attenuation mechanism online and cannot quantify the system recovery capability are solved, and the durability and the toughness of the proton exchange membrane electrolytic cell under the dynamic working condition can be comprehensively and accurately evaluated.

Description

Technical Field

[0001] This invention relates to the field of electrochemical testing technology, and in particular to an accelerated stress testing method based on a proton exchange membrane (PEM) electrolyzer. Background Technology

[0002] Proton exchange membrane (PEM) electrolyzers are one of the key technologies for large-scale green hydrogen production, and their long-term operational durability is a core indicator determining their commercial application prospects. Accelerated stress testing (AST) is the main method for evaluating the durability of electrolyzers, which simulates the aging process of the equipment in a short period of time by applying harsh operating conditions.

[0003] Existing accelerated stress testing methods typically employ open-loop, pre-programmed testing procedures, such as prolonged operation under a constant high current or cyclical switching between fixed high and low currents. These methods suffer from a fundamental technical problem: they treat the testing process as a "black box," passively recording the overall performance degradation only through performance comparisons before and after the test. This approach fails to provide real-time insight into the degradation mechanisms within the electrolyzer during testing, cannot distinguish between recoverable and permanent damage during performance degradation, and cannot measure the electrolyzer's resilience after stress impacts—the system's "toughness." Therefore, the degradation data obtained from existing testing methods have weak correlation with the long-term lifespan of electrolyzers in real-world applications with fluctuating renewable energy sources, failing to provide comprehensive and accurate guidance for material selection and operational strategy optimization. Summary of the Invention

[0004] This invention provides an accelerated stress testing method based on a proton exchange membrane (PEM) electrolyzer, aiming to solve the technical problems of existing accelerated stress testing methods being unable to evaluate performance degradation mechanisms online and quantify system recovery capabilities.

[0005] In view of the above problems, the present invention provides an accelerated stress testing method based on a proton exchange membrane (PEM) electrolyzer, the method comprising: A cyclically varying dynamic electrical load stress is applied to the proton exchange membrane electrolyzer; During the application of the dynamic electrical load stress, transient diagnostics are performed simultaneously to obtain electrochemical parameters characterizing the transient response of the proton exchange membrane electrolyzer. The electrochemical parameters are evaluated in real time and compared with preset health state triggering conditions; When the electrochemical parameters meet the triggering conditions, the application of the dynamic electrical load stress is interrupted, and a recovery protocol aimed at restoring the performance of the proton exchange membrane electrolyzer is automatically triggered and executed. After the recovery protocol is completed, the transient diagnostics are performed again to obtain the electrochemical parameters after recovery and to evaluate the effectiveness of the recovery protocol.

[0006] The technical solution provided in this application has at least the following technical effects: Transient diagnostics are performed simultaneously during dynamic stress testing, and electrochemical parameters are acquired in real time, enabling online monitoring and mechanistic analysis of the performance degradation process, thus overcoming the limitations of traditional "black box" testing.

[0007] By triggering the recovery protocol and comparing parameters before and after, the performance degradation is divided into recoverable and permanent damage parts, and the dynamic toughness coefficient is calculated, providing a key quantitative indicator for the dynamic durability of the electrolyzer.

[0008] By employing dynamic load stress and focusing on system resilience, this method can more accurately reflect the real aging behavior of electrolyzers in fluctuating renewable energy scenarios than traditional static or simple cyclic testing, thus improving the reliability of lifetime prediction.

[0009] The provided attenuation dynamics and toughness data can provide accurate and direct basis for the screening and improvement of key materials, as well as the formulation of optimal operation and maintenance strategies (such as recovery timing), thus accelerating the research and development process. Attached Figure Description

[0010] Figure 1 This is a flowchart of an accelerated stress testing method based on a proton exchange membrane (PEM) electrolyzer, as described in an embodiment of the present invention. Detailed Implementation

[0011] The above technical solutions will now be described in detail with reference to the accompanying drawings and specific embodiments to provide a better understanding of them. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be understood that the present invention is not limited to the exemplary embodiments used only to explain the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the drawings, not all of them.

[0012] Please see Figure 1 An accelerated stress testing method based on a proton exchange membrane (PEM) electrolyzer, the method comprising: A cyclically varying dynamic electrical load stress is applied to the proton exchange membrane electrolyzer; During the application of the dynamic electrical load stress, transient diagnostics are performed simultaneously to obtain electrochemical parameters characterizing the transient response of the proton exchange membrane electrolyzer. The electrochemical parameters are evaluated in real time and compared with preset health state triggering conditions; When the electrochemical parameters meet the triggering conditions, the application of the dynamic electrical load stress is interrupted, and a recovery protocol aimed at restoring the performance of the proton exchange membrane electrolyzer is automatically triggered and executed. After the recovery protocol is completed, the transient diagnostics are performed again to obtain the electrochemical parameters after recovery and to evaluate the effectiveness of the recovery protocol.

[0013] The accelerated stress testing method disclosed in this invention is implemented through a testing system integrating a programmable DC power supply, an electrochemical impedance spectroscopy analyzer, and a main control computer. A control program, which can be written in LabVIEW or Python, runs on the main control computer and serves as the central command for implementing the method. The entire process begins with the cyclical execution of dynamic stress and diagnostics on the proton exchange membrane electrolyzer.

[0014] This cyclic execution phase is scheduled and executed by the control program on the main control computer. The control program first applies dynamic electrical load stress. This step begins with setting the cyclic waveform parameters. The control program's user interface provides input fields for the operator to input parameters such as peak current density, valley current density, current holding time, and switching cycle. In one specific implementation, the peak current density is set to 3A / cm², the valley current density is set to 1A / cm², and the current holding time is set to 30 seconds. These parameters are read by the control program and stored in memory.

[0015] After the settings are completed, the control program enters the drive and execution steps of the programmable DC power supply. The control program communicates with the programmable DC power supply through a universal interface bus. Based on the waveform parameters stored in memory, the control program generates a series of discrete current setpoint instructions. These instructions are sent to the programmable DC power supply one by one according to a preset time sequence. After receiving the instructions, the programmable DC power supply adjusts its output current, thereby applying a cyclically changing dynamic electrical load stress to the connected proton exchange membrane electrolyzer.

[0016] During the application of dynamic electrical load stress, the control program simultaneously performs transient diagnostics. This diagnostics begins with the identification and triggering of load step moments. The control program continuously monitors the actual output current value of the programmable DC power supply through the data acquisition interface at a sampling period of 1 millisecond. The control program internally employs a current change rate monitoring algorithm, which calculates the current difference between two consecutive sampling points in real time. When this difference exceeds a preset step recognition threshold, such as 2 A / cm² per millisecond, the control program determines that a load step moment has occurred.

[0017] At the instant the load step change occurs, the control program immediately sends a trigger signal to the electrochemical impedance spectroscopy (EIS) analyzer via a synchronous trigger interface. This signal transmission is part of a rapid frequency sweep to acquire transient EIS spectra. Upon receiving the trigger signal, the EIS analyzer immediately applies a preset AC excitation signal to the proton exchange membrane electrolyzer. This AC excitation signal is a small-amplitude sinusoidal voltage perturbation containing multiple discrete frequency points, ranging from 10 kHz to 1 Hz, with a perturbation voltage amplitude of 10 mV. The analyzer simultaneously records the AC current response of the electrolyzer under this AC excitation. The entire AC excitation and recording process is completed within 500 milliseconds. The output of this step is a set of data points containing the frequency, real part of impedance, and imaginary part of impedance.

[0018] After acquiring the data point set, the control program then constructs the transient Nyquist plot. The program calls a plotting function library, using the real part of the impedance from the acquired data point set as the x-axis and the negative of the imaginary part of the impedance as the y-axis, to plot the data in a two-dimensional coordinate system. Thus, a transient Nyquist plot representing the transient response is constructed and displayed on the user interface, while the plot data is stored on the local hard drive.

[0019] After constructing and storing the transient Nyquist plot, the control program then performs a real-time assessment and comparison of the health status. This step begins with the extraction of transient electrochemical parameters. The control program invokes a data fitting algorithm module to process the transient Nyquist plot data constructed in the previous step. This data fitting algorithm uses an equivalent circuit model for fitting; in one specific implementation, this model includes an ohmic resistor, a constant phase angle element, and a charge transfer resistor. Through nonlinear least squares fitting, the algorithm extracts the transient high-frequency resistance from the intersection of the high-frequency region and the real axis in the plot, and extracts the transient charge transfer resistance from the diameter of the semicircular arc in the plot. These extracted resistance values, as transient electrochemical parameters, are stored as a loop array in memory, which records the parameter values ​​of the most recent 100 loops.

[0020] After obtaining the transient electrochemical parameters for the current cycle, the control program immediately performs a trigger condition judgment based on absolute value and rate of change thresholds. The control program has two parallel judgment logic branches. In the first logic branch, the program compares the transient charge transfer resistance value extracted in this cycle with a preset absolute value threshold stored in a configuration file. In the second logic branch, the program calls a linear regression algorithm to linearly fit the most recent 10 transient charge transfer resistance values ​​stored in the memory loop array, calculates the incremental rate of change of these parameters over time, and compares this rate of change with a preset rate of change threshold. When the comparison result of either logic branch is true, for example, if the transient charge transfer resistance value exceeds 50% of its initial reference value, or its incremental rate of change exceeds 0.1 mΩ / cycle, the control program determines that the health state trigger condition has been met.

[0021] If the triggering condition is not met, the control program returns to the dynamic electrical load stress application step and continues to execute the next test cycle. If the triggering condition is met, the control program enters the adaptive triggering and execution phase of the recovery protocol.

[0022] This phase begins with the triggering decision of the recovery protocol. The control program first executes the generation of an interrupt instruction. The program creates an interrupt flag in memory and sets its value to "true". Simultaneously, the program generates a mode switching instruction containing the necessary parameters to switch the test system from dynamic current control mode to constant voltage control mode. After generating the instruction, the control program immediately executes the interruption of dynamic electrical load stress. The program stops sending a series of instructions to the programmable DC power supply to generate dynamic waveforms and instead sends an instruction to set the output current to zero, thereby interrupting the application of dynamic electrical load stress to the proton exchange membrane electrolyzer.

[0023] After the dynamic electrical load stress is interrupted, the control program then executes the recovery protocol. This step begins with the setting and loading of the constant voltage operating condition. The control program sends a previously generated mode switching command to the programmable DC power supply. This command switches its operating mode to constant voltage output mode. The command includes a preset constant voltage value, which in one specific implementation is 1.45V. Upon receiving the command, the programmable DC power supply adjusts its output to apply and maintain this constant voltage to the proton exchange membrane electrolyzer.

[0024] After the constant voltage condition is applied, the control program synchronously initiates control over the duration of the recovery protocol execution. Internally, a timer module is started and a preset recovery duration, such as 2 hours, is set. The timer begins counting down, and during this period, the control program continuously maintains the constant voltage output. When the timer reaches the preset duration, the control program determines that the recovery protocol has been completed and stops sending constant voltage commands to the programmable DC power supply, causing its output to become zero.

[0025] After the recovery protocol is completed, the control program then enters the quantification and adaptive adjustment phase of the recovery effect.

[0026] This stage begins with a re-diagnosis of the recovered state. The control program first performs a transient diagnosis after recovery. This step reuses the aforementioned transient diagnosis process, whereby the control program sends a command to the programmable DC power supply to apply a current step from the valley current density to the peak current density. At the instant the step occurs, the control program simultaneously triggers the electrochemical impedance spectroscopy analyzer to perform a rapid frequency sweep operation with the same specifications as described above. After the frequency sweep is completed, the control program immediately executes the step of acquiring the electrochemical parameters after recovery. The program also calls the data fitting algorithm module to fit the transient electrochemical impedance spectroscopy data acquired in this diagnosis, extracts the recovered transient charge transfer resistance value, and stores it in a specified variable in memory.

[0027] After obtaining the recovered electrochemical parameters, the control program proceeds to determine the dynamic toughness coefficient. This step begins with the calculation of recoverable and total attenuation. The control program reads three key parameters from memory: the last transient charge transfer resistance value recorded before triggering the recovery protocol, the transient charge transfer resistance value acquired after this recovery, and the initial reference transient charge transfer resistance value stored before the test began. The program first subtracts the recovered resistance value from the resistance value before triggering the recovery; this difference is defined as the recoverable attenuation. Next, the program subtracts the initial reference resistance value from the resistance value before triggering the recovery; this difference is defined as the total attenuation.

[0028] After calculating the two attenuation values, the control program immediately generates a dynamic resilience coefficient based on the ratio of the attenuation values. The program divides the recoverable attenuation value calculated in the previous step by the total attenuation value, and the quotient is determined as the dynamic resilience coefficient for this recovery cycle. This coefficient value is appended with a timestamp and, along with the specific values ​​of the two attenuation values, is stored as a data record in the test log file on the local hard drive.

[0029] After determining and recording the dynamic toughness coefficient, the control program then performs adaptive adjustments to the dynamic electrical load stress. This step begins with a comparison between the dynamic toughness coefficient and a toughness threshold. The control program compares the newly generated dynamic toughness coefficient value with a preset toughness threshold, such as 0.8, stored in a configuration file.

[0030] Based on the comparison results, the control program adjusts the peak current density parameter. If the dynamic toughness coefficient value is greater than or equal to the toughness threshold, it indicates that the electrolyzer has recovered well, and the control program does not perform parameter adjustment. If the dynamic toughness coefficient value is lower than the toughness threshold, it indicates that the electrolyzer has experienced significant permanent degradation, and the control program will perform parameter adjustment. Specifically, the program reads the peak current density parameter stored in memory and multiplies it by a preset attenuation factor, such as 0.95, to obtain a new, lower peak current density value. The control program then uses this new value to update the cyclic waveform parameters in memory.

[0031] After completing the adaptive adjustment, the control program resets the interrupt flag to "false" and returns to the dynamic stress and diagnostic loop execution phase. Using the updated (or unchanged) waveform parameters, it begins a new round of accelerated stress testing. The entire process thus forms a closed loop, terminating after the preset total test duration or total number of loops is reached.

[0032] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. Therefore, the patent protection scope of the present invention should be determined by the scope defined in the claims.

Claims

1. A method of accelerated stress testing of a proton exchange membrane (PEM) electrolyzer, characterized by, The method comprises: applying a cyclically varying dynamic electrical load stress to the proton exchange membrane electrolyzer; synchronously performing a transient diagnosis to obtain electrochemical parameters characterizing the transient response of the proton exchange membrane electrolyzer during the application of the dynamic electrical load stress; evaluating the electrochemical parameters in real time and comparing them with preset health state triggering conditions; when the electrochemical parameters meet the triggering conditions, interrupting the application of the dynamic electrical load stress and automatically triggering and executing a recovery protocol aimed at restoring the performance of the proton exchange membrane electrolyzer; after the execution of the recovery protocol, performing the transient diagnosis again to obtain the electrochemical parameters after the recovery and evaluating the effect of the recovery protocol.

2. A method of accelerated stress testing of a proton exchange membrane (PEM) electrolyzer cell according to claim 1, characterized in that, The step of evaluating the effect of the recovery protocol further comprises: quantifying the ratio of the recoverable part to the permanent part in the performance degradation of the proton exchange membrane electrolyzer by comparing the electrochemical parameters before and after the execution of the recovery protocol, to determine a dynamic resilience coefficient.

3. A method of accelerated stress testing of a proton exchange membrane (PEM) electrolyzer cell according to claim 2, characterized in that, The step of determining the dynamic resilience coefficient comprises: defining the difference between the electrochemical parameters after the execution of the recovery protocol and the electrochemical parameters before the execution as a recoverable attenuation amount; defining the difference between the electrochemical parameters before the execution of the recovery protocol and the initial baseline electrochemical parameters as a total attenuation amount; the dynamic resilience coefficient is determined by the ratio of the recoverable attenuation amount to the total attenuation amount.

4. The accelerated stress test method of a proton exchange membrane (PEM) electrolyzer according to claim 1, wherein, The step of performing the transient diagnosis specifically comprises: synchronously triggering and performing a rapid frequency sweep at the moment when the dynamic electrical load stress occurs to obtain the transient electrochemical impedance spectrum of the proton exchange membrane electrolyzer.

5. A method of accelerated stress testing of a proton exchange membrane (PEM) electrolyzer cell according to claim 4, characterized in that, The rapid frequency sweep is performed in a preset frequency range to construct a transient Nyquist plot characterizing the transient response.

6. The accelerated stress test method of a proton exchange membrane (PEM) electrolyzer cell according to claim 1, wherein, The health state triggering conditions include at least one of: the incremental value of the electrochemical parameters exceeds a preset absolute value threshold; the incremental change rate of the electrochemical parameters exceeds a preset change rate threshold.

7. A method of accelerated stress testing of a proton exchange membrane (PEM) electrolyzer cell according to claim 1, wherein, The recovery protocol comprises: running the proton exchange membrane electrolyzer under the working condition of constant voltage.

8. A method of accelerated stress testing of a proton exchange membrane (PEM) electrolyzer cell according to claim 3, wherein, The method further comprises: based on the dynamic resilience coefficient, adaptively adjusting the parameters of the subsequently applied dynamic electrical load stress; wherein the adjustment comprises: when the dynamic resilience coefficient is lower than a preset resilience threshold, reducing the peak current density of the subsequently applied dynamic electrical load stress.

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