Electrochemical multi-parameter acquisition and joint analysis method for corrosion process of titanium-based material for bipolar plate
By employing multi-parameter acquisition and joint analysis methods using an electrochemical workstation, the problem of low data correlation in the corrosion resistance test of bipolar plates in proton exchange membrane fuel cells was solved, enabling a deeper understanding of the corrosion process of titanium-based materials and an accurate evaluation of their corrosion resistance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2023-03-23
- Publication Date
- 2026-04-24
AI Technical Summary
In the existing technology, the corrosion resistance test of bipolar plates in proton exchange membrane fuel cells shows low correlation between individual constant potential polarization and AC impedance data under constant potential, and there is a lack of methods for simultaneous acquisition and joint testing and analysis of multiple types of data.
An electrochemical workstation was used to alternately measure the AC impedance spectroscopy and monitor the open circuit potential of titanium-based materials. Combined with bias AC impedance spectroscopy, multi-parameter acquisition and joint analysis were conducted, including comprehensive analysis of corrosion current density, bias impedance and open circuit potential. The relationship between effective corrosion current density and time was plotted to analyze the corrosion electrochemical process of titanium-based materials.
This enables a more accurate evaluation of the corrosion resistance of titanium-based materials, reveals their decay patterns during service, provides stronger data correlation and more accurate corrosion mechanism research, and supports the rational selection of titanium-based materials and surface treatment processes suitable for fuel cells.
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Figure CN116499960B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of new energy, specifically relating to a method for simultaneous acquisition and analysis of multiple electrochemical parameters of titanium-based materials used in the corrosion process of proton exchange membrane fuel cell bipolar plates, for use in corrosion resistance testing and corrosion mechanism research. Background Technology
[0002] The corrosion resistance of bipolar plates used in proton exchange membrane fuel cells is mostly tested using an electrochemical workstation under simulated operating conditions. Commonly used tests include potentiodynamic polarization, potentiostatic polarization, AC impedance, and open-circuit potential changes over time. Current literature generally employs single-type data measurement and analysis (potentialostatic polarization curves or single potentiostatic AC impedance analysis) or dual-type data measurement (open-circuit potential and AC impedance spectrum at open-circuit potential). Therefore, improvements are needed in the simultaneous acquisition of multiple data types and the quasi-simultaneous joint testing and analysis of multiple data types. Summary of the Invention
[0003] The purpose of this invention is to address the shortcomings of existing metal bipolar plate corrosion resistance testing techniques, such as the lack of correlation between data obtained from individual constant potential polarization and AC impedance under constant potential, and to provide a method for electrochemical multi-parameter acquisition and joint analysis of corrosion process of titanium-based materials for proton exchange membrane fuel cells.
[0004] The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates of the present invention is implemented according to the following steps:
[0005] 1. The bipolar plate made of titanium-based material was placed in an electrolyte solution containing 0.0005 mol / L H2SO4 and 0.1 ppm HF. The AC impedance spectrum was acquired under bias voltage using the AC impedance measurement program of the electrochemical workstation. A three-electrode system was used, with the titanium-based material as the working electrode. The AC impedance measurement program was performed alternately (in combination) with bias voltage AC impedance spectroscopy measurement and open circuit potential monitoring. An open circuit potential monitoring was performed for 1800 s before each bias voltage impedance spectroscopy measurement and the measurement ended with an open circuit potential monitoring for 1800 s.
[0006] II. During the bias AC impedance spectroscopy measurement process, the average current density value I of a single impedance data point is obtained by observing the potential and current relationship (curve) under a sinusoidal signal. a This is the corrosion current density at that impedance data point;
[0007] 3. During each bias AC impedance spectroscopy measurement, the effective corrosion current density within the test time is calculated using the corrosion current density at all impedance data points. Plot the relationship between the effective corrosion current density and time in all bias AC impedance spectroscopy measurements with the impedance spectroscopy acquisition time as the abscissa and the effective corrosion current density as the ordinate, showing the abrupt changes in the effective corrosion current density.
[0008] 4. Plot the Nyquist plot of the bias AC impedance spectrum and the open circuit potential change plot before AC impedance testing. By analyzing the abrupt change in the effective corrosion current density, the change in the size of the capacitive arc in the Nyquist plot, and the change in the open circuit potential curve, the corrosion electrochemical process of titanium-based materials for bipolar plates can be analyzed.
[0009] In step one, the bias voltage is controlled at 0.6V for the AC impedance spectrum measurement, the AC signal amplitude is 10–20mV, and the frequency range of the bias AC is controlled at 10. 5 Hz~10 -2 Hz.
[0010] In the electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates of the present invention, step one is the electrochemical multi-parameter acquisition process, and steps two to four are the data processing and joint analysis processes.
[0011] This invention proposes a method for testing the corrosion performance of titanium-based materials for bipolar plates. This method involves simultaneously collecting corrosion current density caused by bias voltage, the evolution of bias voltage impedance, and the intermittent open-circuit potential of bias voltage impedance. By comprehensively analyzing the evolution of corrosion current density, bias voltage impedance, and open-circuit potential within the same time period, the decay law of bipolar plate materials during service can be revealed, thereby more accurately evaluating the corrosion resistance of titanium-based materials during service. Attached Figure Description
[0012] Figure 1 This is a schematic diagram illustrating the combined measurement of bias AC impedance and open-circuit potential in the embodiment;
[0013] Figure 2 This is a schematic diagram showing the relationship between the potential and current of a sine wave during the testing of a single impedance data point in the embodiment.
[0014] Figure 3 This is a test graph of the corrosion current density at each impedance point during the 10th AC impedance spectrum monitoring under a 0.6V bias voltage in the example.
[0015] Figure 4 This is a graph showing the evolution of the effective corrosion current density over time during AC impedance spectral monitoring (from the 1st to the 72nd) at a bias voltage of 0.6V in the example.
[0016] Figure 5The figure shows the evolution of the first to 14 AC impedance spectra under a 0.6V bias voltage in the example. The numbers in the figure represent which AC impedance spectrum was monitored. For example, a represents the first bias voltage AC impedance spectrum measurement, and b represents the third bias voltage AC impedance spectrum measurement.
[0017] Figure 6 This is a time evolution diagram of the 15th-27th AC impedance spectra under a 0.6V bias voltage in the example;
[0018] Figure 7 This is a time evolution diagram of the 28th-35th AC impedance spectra under a 0.6V bias voltage in the example;
[0019] Figure 8 This is a time evolution diagram of the 36th-46th AC impedance spectrum under a 0.6V bias voltage in the example;
[0020] Figure 9 This is a time evolution diagram of the 48th-67th AC impedance spectra under a 0.6V bias voltage in the example;
[0021] Figure 10 This is a time evolution diagram of the 68th-72nd AC impedance spectrum under a 0.6V bias voltage in the example;
[0022] Figure 11 This is a graph showing the evolution of open-circuit potential over time before the 1st to 14th AC impedance spectrum measurements under a 0.6V bias voltage in the example. For example, a represents the 1st open-circuit potential monitoring, and b represents the 3rd open-circuit potential monitoring.
[0023] Figure 12 This is a graph showing the evolution of the open-circuit potential over time before the 15th-27th AC impedance spectrum measurements under a 0.6V bias voltage in the example.
[0024] Figure 13 This is a graph showing the evolution of the open-circuit potential over time before the 28th-35th AC impedance spectrum measurements under a 0.6V bias voltage in the example.
[0025] Figure 14 This is a graph showing the evolution of the open-circuit potential over time before the 36th-46th AC impedance spectrum measurement under a 0.6V bias voltage in the example.
[0026] Figure 15 This is a graph showing the evolution of the open-circuit potential over time before the 48th-67th AC impedance spectrum measurements under a 0.6V bias voltage in the example.
[0027] Figure 16 This is a graph showing the evolution of the open-circuit potential over time before the 68th-73rd AC impedance spectrum measurements under a 0.6V bias voltage in the example. Detailed Implementation
[0028] Specific Implementation Method 1: The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates in this implementation method is carried out according to the following steps:
[0029] 1. The bipolar plate made of titanium-based material was placed in an electrolyte solution containing 0.0005 mol / L H2SO4 and 0.1 ppm HF. The AC impedance spectrum was acquired under bias voltage using the AC impedance measurement program of the electrochemical workstation. A three-electrode system was used, with the titanium-based material as the working electrode. The AC impedance measurement program was performed alternately (in combination) with bias voltage AC impedance spectroscopy measurement and open circuit potential monitoring. An open circuit potential monitoring was performed for 1800 s before each bias voltage impedance spectroscopy measurement and the measurement ended with an open circuit potential monitoring for 1800 s.
[0030] II. During the bias AC impedance spectroscopy measurement process, the average current density value I of a single impedance data point is obtained by observing the potential and current relationship (curve) under a sinusoidal signal. a This is the corrosion current density at that impedance data point;
[0031] 3. During each bias AC impedance spectroscopy measurement, the effective corrosion current density within the test time is calculated using the corrosion current density at all impedance data points. Plot the relationship between the effective corrosion current density and time in all bias AC impedance spectroscopy measurements with the impedance spectroscopy acquisition time as the abscissa and the effective corrosion current density as the ordinate, showing the abrupt changes in the effective corrosion current density.
[0032] 4. Plot the Nyquist plot of the bias AC impedance spectrum and the open circuit potential change plot before AC impedance testing. By analyzing the abrupt change in the effective corrosion current density, the change in the size of the capacitive arc in the Nyquist plot, and the change in the open circuit potential curve, the corrosion electrochemical process of titanium-based materials for bipolar plates can be analyzed.
[0033] In step one, the bias voltage is controlled at 0.6V for the AC impedance spectrum measurement, the AC signal amplitude is 10–20mV, and the frequency range of the bias AC is controlled at 10. 5 Hz~10 -2 Hz.
[0034] In this embodiment, the bias AC impedance spectrum measurement uses a small-amplitude AC sinusoidal potential wave, with the frequency of the sinusoidal potential wave varying from large to small.
[0035] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the area of the titanium-based material used for the bipolar plate in step one is 1 cm². 2 .
[0036] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the temperature of the electrolyte solution in step 1 is 20-90℃.
[0037] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the bias voltage in step one is controlled at 0.6V and the AC signal amplitude is 10mV.
[0038] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the reference electrode in the three-electrode system in step 1 is an Ag / AgCl electrode, and the counter electrode is a graphite plate.
[0039] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the bias AC impedance spectrum measurement and open circuit potential monitoring are performed 70 to 80 times each in the AC impedance measurement procedure in step one.
[0040] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the AC impedance measurement procedure in step one includes 72 bias AC impedance spectrum measurements and 73 open-circuit potential monitoring measurements.
[0041] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the measurement time for each bias AC impedance spectrum in Step One is 1800 to 2500 seconds.
[0042] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the measurement time for each bias AC impedance spectrum in step one is 2000s.
[0043] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that 71 impedance data points are set in each bias AC impedance spectrum measurement process in step 1.
[0044] Example: The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based bipolar plates in this example is implemented according to the following steps:
[0045] 1. Place the bipolar plate TC4 titanium alloy sample in an electrolyte solution containing 0.0005 mol / L H2SO4 and 0.1 ppm HF, with an exposure area of 1 cm². 2 AC impedance spectroscopy under bias voltage was acquired using the AC impedance measurement program of the Gamry electrochemical workstation. A three-electrode system was used, with the working electrode being a TC4 titanium alloy sample, the reference electrode being an Ag / AgCl electrode, and the counter electrode being a graphite plate. The AC impedance measurement program alternated (combined) with bias voltage AC impedance spectroscopy measurement and open-circuit potential monitoring. Each bias voltage AC impedance spectroscopy measurement lasted for 2000 s, and an open-circuit potential monitoring was performed for 1800 s before each bias voltage AC impedance spectroscopy measurement and at the end of the measurement. In this embodiment, a total of 72 bias voltage AC impedance spectroscopy measurements and 73 open-circuit potential monitoring were performed.
[0046] II. During the bias AC impedance spectroscopy measurement process, the average current density value I of a single impedance data point is obtained by observing the potential and current relationship (curve) under a sinusoidal signal. a This is the corrosion current density at that impedance data point;
[0047] 3. During each bias AC impedance spectroscopy measurement, the effective corrosion current density within the test time is calculated using the corrosion current density at all impedance data points. Plot the relationship between the effective corrosion current density and time in all bias AC impedance spectroscopy measurements with the impedance spectroscopy acquisition time as the abscissa and the effective corrosion current density as the ordinate, showing the abrupt changes in the effective corrosion current density.
[0048] 4. Plot the Nyquist plot of the bias AC impedance spectrum and the open circuit potential change plot before AC impedance testing. By analyzing the abrupt change in the effective corrosion current density, the change in the size of the capacitive arc in the Nyquist plot, and the change in the open circuit potential curve, the corrosion electrochemical process of titanium-based materials for bipolar plates can be analyzed.
[0049] The parameters for the bias AC impedance spectroscopy measurement in step one are shown in Table 1 below.
[0050] Table 1. Parameters for AC impedance spectroscopy under bias voltage.
[0051]
[0052] like Figure 3 As shown, taking the impedance spectrum obtained from the 10th bias AC impedance spectrum measurement as an example, Figure 2 This represents the corrosion current density corresponding to the impedance data points measured at a bias voltage of 0.6V. Figure 3 The horizontal axis represents the recording time of each impedance point after the impedance spectrum acquisition began. Impedance data was measured from high frequency to low frequency. The graph shows that the corrosion current density is relatively high at the beginning of high-frequency impedance measurement, reaching 5 × 10⁻⁶. -4 A / cm 2 Later, when measuring low-frequency impedance, the corrosion current density was as low as 1×10⁻⁶. -5 A / cm 2 .
[0053] Will Figure 3 The current density-time curve is integrated over time to obtain the effective value of the corrosion current density for each impedance spectroscopy test time. The evolution of the effective corrosion current density obtained from AC impedance spectroscopy monitoring at all 72 bias voltages with time (taking the time point after impedance spectroscopy acquisition) is as follows: Figure 4 As shown, the effective corrosion current density of TC4 titanium alloy during impedance testing at a bias voltage of 0.6V is 4×10⁻⁶. -5 A / cm 2Up to 4×10 -4 A / cm 2 The effective corrosion current density curve is discontinuous, divided into 6 segments, with the breakpoints located at points such as... Figure 4 The light gray shaded area shown.
[0054] like Figure 5-10 As shown, the evolution of the AC impedance spectrum is based on Figure 4 These six equivalent corrosion current densities are divided into six groups. In the Nyquist plots of impedance spectra 1 to 14 of the first group, the capacitive arc first increases and then decreases. In the Nyquist plots of impedance spectra 15 to 27 of the second group, the capacitive arc gradually decreases. In the Nyquist plots of impedance spectra 28 to 35 of the third group and impedance spectra 36 to 46 of the fourth group, the capacitive arc gradually decreases. Among them, the capacitive arcs of impedance spectra 28 and 36 are of similar size, and the capacitive arcs of impedance spectra 35 and 46 are of similar size. In the Nyquist plots of impedance spectra 48 to 66 of the fifth group, the capacitive arc size generally shows a decreasing trend, and finally the impedance spectrum 67 shows a slight increase. In the Nyquist plots of impedance spectra 68 to 72 of the sixth group, the trend of decreasing is still observed.
[0055] The size of the capacitive arc in each impedance group generally shows a decreasing trend, with the size of the first capacitive arc in each group being similar. The size of the capacitive arc decreases slowly within each stage; when the next stage begins, the size of the capacitive arc suddenly increases to a larger value.
[0056] contrast Figure 4 and Figure 5-10 It can be observed that the size of the capacitive arc is negatively correlated with the effective current density.
[0057] Figure 11-16 The diagram shows the open-circuit potential changes before the AC impedance test, also divided into six groups in sequence. Figure 4 The comparison revealed that a sudden decrease in open-circuit potential preceded each abrupt change in the effective value of the equivalent corrosion current density. Open-circuit potentials 14 and 24 showed a sharp drop of 100 mV around 300 s; open-circuit potential 35 showed a sharp drop of 600 mV around 900 s; open-circuit potential 46 showed a precursor to a sharp drop at 1800 s, but the value after the drop could not be monitored due to the lack of longer measurement time; open-circuit potential 58 also showed a precursor to a sharp drop. Nine curves from open-circuit potentials 59 to 67 showed consecutive and significant sharp drops, with a drop of up to 600 mV, and the timing of the sharp drops occurred progressively earlier.
[0058] For metal corrosion, a decrease in open-circuit potential (generally) corresponds to the rupture of the surface film, while an increase in open-circuit potential corresponds to passivation or the formation of a protective film. A comprehensive comparative analysis of the equivalent corrosion current density, bias AC impedance spectrum, and the evolution of the open-circuit potential curve reveals that during the service of titanium alloys in corrosive media (under constant potential), the surface film will be damaged, manifested as a sudden drop in open-circuit potential. Subsequently, the damaged points are repaired to some extent by constant potential polarization, resulting in the open-circuit potential returning to a higher value. Frequent sudden drops in open-circuit potential occur between impedances of 58 and 67, with the drop occurring earlier and earlier, indicating that constant potential polarization does not completely repair the film during this stage. After impedance reaches 68, the coating enters a normal passivation state without a sudden drop in open-circuit potential.
[0059] This invention utilizes simultaneous acquisition of multiple electrochemical parameters (corrosion current density at constant potential, AC impedance spectrum at constant potential, and open-circuit potential during impedance measurement intervals) for comprehensive analysis, effectively revealing the electrochemical corrosion process of metal surfaces. Compared to conventional separate acquisition of electrochemical parameters, the data exhibits stronger correlation, leading to more accurate conclusions. This method helps to deeply reveal the decay patterns of titanium-based materials during corrosion and accurately evaluate their corrosion resistance during service. Titanium-based materials with good corrosion resistance exhibit lower effective corrosion current densities and delayed abrupt changes, larger capacitive arcs with minimal time variation, and relatively lower frequencies of sharp drops in open-circuit potential. Ultimately, this achieves the goal of rationally selecting titanium-based materials and surface treatment processes that meet the service environment requirements of fuel cells.
Claims
1. An electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates, characterized in that... The electrochemical multi-parameter acquisition and joint analysis method is implemented according to the following steps:
1. The bipolar plate made of titanium-based material was placed in an electrolyte solution containing 0.0005 mol / L H2SO4 and 0.1 ppm HF. The AC impedance spectrum was acquired under bias voltage using the AC impedance measurement program of the electrochemical workstation. A three-electrode system was used, with the titanium-based material as the working electrode. The AC impedance measurement program alternated between bias voltage AC impedance spectrum measurement and open circuit potential monitoring. An open circuit potential monitoring was performed for 1800 s before each bias voltage impedance spectrum measurement and ended with an open circuit potential monitoring for 1800 s. II. During the bias AC impedance spectroscopy measurement process, the average current density value I of a single impedance data point is obtained by analyzing the potential and current relationship under a sinusoidal signal. a This is the corrosion current density at that impedance data point; 3. During each bias AC impedance spectroscopy measurement, the effective corrosion current density within the test time is calculated using the corrosion current density at all impedance data points. Plot the relationship between the effective corrosion current density and time in all bias AC impedance spectroscopy measurements with the impedance spectroscopy acquisition time as the abscissa and the effective corrosion current density as the ordinate, showing the abrupt changes in the effective corrosion current density.
4. Plot the Nyquist plot of the bias AC impedance spectrum and the open-circuit potential change plot before AC impedance testing. By analyzing the abrupt change in the effective corrosion current density, the change in the size of the capacitive arc in the Nyquist plot, and the change in the open-circuit potential curve, the corrosion electrochemical process of titanium-based materials for bipolar plates can be analyzed. In step one, the bias voltage is controlled at 0.6V for the AC impedance spectrum measurement, the AC signal amplitude is 10–20mV, and the frequency range of the bias AC is controlled at 10. 5 Hz~10 -2 Hz.
2. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 1, characterized in that... In step one, the area of the titanium-based material used for the bipolar plate is 1 cm². 2 .
3. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 1, characterized in that... The temperature of the electrolyte solution in step one is 20–90°C.
4. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 1, characterized in that... In step one, the bias voltage is controlled to be 0.6V and the AC signal amplitude is 10mV.
5. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 1, characterized in that... In step one, the reference electrode in the three-electrode system is an Ag / AgCl electrode, and the counter electrode is a graphite plate.
6. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 1, characterized in that... In step one, the AC impedance measurement procedure involves performing bias AC impedance spectrum measurement and open circuit potential monitoring 70 to 80 times each.
7. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 6, characterized in that... In step one, the AC impedance measurement procedure includes 72 bias AC impedance spectrum measurements and 73 open-circuit potential monitoring measurements.
8. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 1, characterized in that... In step one, the measurement time for each bias voltage AC impedance spectrum is 1800–2500 s.
9. The electrochemical multi-parameter acquisition and joint analysis method for the corrosion process of titanium-based materials for bipolar plates according to claim 8, characterized in that... In step one, the measurement time for each bias AC impedance spectrum is 2000s.
10. The method for electrochemical multi-parameter acquisition and joint analysis of the corrosion process of titanium-based materials for bipolar plates according to claim 1, characterized in that... In step one, 71 impedance data points are set during each bias AC impedance spectrum measurement process.