Method for predicting service life of bipolar plate coating of fuel cell

Abstract

The invention provides a fuel cell bipolar plate coating life prediction method, and the method comprises the steps: determining a termination condition of a bipolar plate coating life test; based on the accelerated corrosion test platform and the simulated cathode potential of the fuel cell under the normal operation condition, performing an off-line real life test on the bipolar plate coating to obtain a first corresponding relation between the contact resistance and the real test time; adjusting a test condition, and performing an offline accelerated life test on the fuel cell bipolar plate coating to obtain a second corresponding relation between the contact resistance and the accelerated test time and a corresponding first accelerated test duration when the offline accelerated life test reaches a termination condition; obtaining a mapping relation between the real test time and the accelerated test time based on the first corresponding relation and the second corresponding relation; and obtaining a prediction result of the service life of the fuel cell bipolar plate coating based on the first acceleration test duration and a mapping relation between the real test time and the acceleration test time. The prediction accuracy is improved; and the prediction cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of coating life testing, and in particular to a method for predicting the coating life of a fuel cell bipolar plate. Background Art

[0002] In the prior art, the fuel cell bipolar plate coating life prediction method uses the actual stack life as a reference, including the functional relationship between the voltage attenuation and the test time during the actual test of the stack endurance, and the functional relationship between the voltage attenuation caused by the increase in contact resistance of the metal bipolar plate coating in the offline test and the test time. Finally, an equivalent relationship between the voltage attenuation is created by the offline accelerated life test of the bipolar plate coating and the actual stack online test: a functional relationship between the offline accelerated life test of the metal bipolar plate coating and the actual stack online test time is established, thereby predicting the fuel cell bipolar plate coating life based on the functional relationship.

[0003] The actual stack test requires a complete set of fuel cell test systems. In order to ensure the reliability of the test, generally at least 2 to 3 test systems are required, and the test system is expensive. In addition, a large amount of hydrogen and oxygen is consumed during the test, which is costly. Moreover, the voltage attenuation of the actual stack test is affected by many factors, including operating conditions, hydrothermal management, membrane electrode performance attenuation, etc. That is, since the actual stack life is affected by many factors, it is difficult to truly and accurately predict the life of the bipolar plate coating, the accuracy is poor, and it is time-consuming and laborious. For example, there is currently no measured life of 10,000 hours in China, but this does not mean that the life of the metal bipolar plate coating cannot reach 10,000 hours. Summary of the invention

[0004] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0005] To this end, the purpose of this application is to propose a method for predicting the life of a fuel cell bipolar plate coating to improve the accuracy of the prediction and reduce the prediction cost.

[0006] To achieve the above objectives, the present application proposes a method for predicting the life of a fuel cell bipolar plate coating, comprising the following steps:

[0007] Under the fuel cell reference current density, the termination condition of the life test of the fuel cell bipolar plate coating is determined based on the proportion of the voltage attenuation caused by the increase in the contact resistance of the fuel cell bipolar plate coating to the initial state voltage of the fuel cell; the fuel cell reference current density is used to characterize the current density corresponding to the first volt value when the average voltage per cell of the fuel cell is the first volt value;

[0008] Based on the accelerated corrosion test platform and the cathode potential under the simulated normal operating conditions of the fuel cell, an offline real life test is performed on the fuel cell bipolar plate coating to obtain a first corresponding relationship between the contact resistance and the real test time;

[0009] Based on the adjusted test conditions of the accelerated corrosion test platform, an offline accelerated life test is performed on the fuel cell bipolar plate coating to obtain a second corresponding relationship between the contact resistance and the accelerated test time and a first accelerated test duration corresponding to when the offline accelerated life test reaches the termination condition;

[0010] Based on the first corresponding relationship and the second corresponding relationship, obtaining a mapping relationship between the real test time and the accelerated test time;

[0011] Based on the first accelerated test duration and the mapping relationship between the actual test time and the accelerated test time, a prediction result of the fuel cell bipolar plate coating life is obtained.

[0012] In some implementations, the first volt value is 0.7 V, and the fuel cell reference current density is 1.8 to 2.0 A / cm 2 .

[0013] In some implementations, the termination condition of the life test of the fuel cell bipolar plate coating is that the voltage decay accounts for a proportion of the initial state voltage of the fuel cell that is greater than 10%.

[0014] In some implementations, the accelerated corrosion testing platform includes an electrochemical workstation, a central control machine, a corrosion testing cell and an oil bath. The corrosion testing cell is used to contain a corrosive liquid and a fuel cell sample to be tested. The corrosion testing cell is provided with an air inlet and an air outlet. The corrosion testing cell is placed in the oil bath. The corrosion testing cell is connected to the electrochemical workstation through a three-electrode system, and the electrochemical workstation is connected to the central control machine.

[0015] In some implementations, the offline real life test and the offline accelerated life test both adopt constant potential polarization test, during which air or oxygen is introduced into the corrosive liquid at a ventilation rate of 10 to 30 ml / min.

[0016] In some implementations, the corrosion environment temperature provided by the accelerated corrosion testing platform is 75-90°C, preferably 80°C; the corrosive medium in the corrosive solution includes H2SO4 and F ions, the pH value of H2SO4 is in the range of 2-4, preferably pH=3; the concentration range of F ions is 0.01-10ppm, preferably 5ppm.

[0017] In some implementations, the first accelerated test duration of the offline accelerated life test is controlled by an acceleration factor, and the acceleration factor includes one or more of increasing the test potential, decreasing the pH value, and increasing the test environment temperature, wherein the increased test potential ranges from 1 to 2 V vs. SHE, the decreased pH value ranges from 0 to 1, and the increased test environment temperature ranges from 90 to 100°C.

[0018] In some implementations, the constant potential polarization potential selected for the offline accelerated life test is 1.4V.

[0019] In some implementations, the cathode potential of the simulated fuel cell under normal operating conditions is 0.74V to 0.84V vs. SHE, preferably 0.84V.

[0020] In some implementations, obtaining a mapping relationship between the real test time and the accelerated test time based on the first corresponding relationship and the second corresponding relationship includes:

[0021] The first corresponding relationship is expressed as R1=f(t1);

[0022] The second corresponding relationship is expressed as R2=h(t2);

[0023] Based on a fixed reference current, a mapping relationship between the real test time t1 and the accelerated test time t2 is established, and the mapping relationship is expressed as follows:

[0024] t2=g(t1).

[0025] The fuel cell bipolar plate coating life prediction method provided in the present application judges the bipolar plate coating failure index by the increase of contact resistance, performs offline actual measurement and offline accelerated test on the bipolar plate coating under the simulated fuel cell operating conditions, and on the basis of obtaining the time required for the accelerated life test to reach the end of life, predicts the life of the bipolar plate coating according to the mapping relationship between the time required for the bipolar plate coating to reach the end of life in the offline accelerated life test and the time taken for the bipolar plate coating to reach the end of life under normal operating conditions; thereby achieving a higher accuracy of the prediction result obtained by using the measured life of the coating as a reference than using the stack life as a reference; at the same time, using the offline accelerated life test instead of the offline life measurement can quickly predict the life of the coating; using the electrochemical workstation to test the coating through a three-electrode system greatly reduces the test cost and improves the test efficiency compared with the prior art; thereby achieving a simple, efficient and accurate prediction of the life of the fuel cell bipolar plate coating, which is conducive to the rapid iteration of coating process research and development.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 A schematic diagram of a process for predicting the life of a fuel cell bipolar plate coating provided in an embodiment of the present application;

[0029] Figure 2 A curve diagram of contact resistance variation at different times in an offline accelerated life test and an offline real life test provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0031] The following describes a method for predicting the life of a fuel cell bipolar plate coating according to an embodiment of the present application with reference to the accompanying drawings.

[0032] Figure 1 A schematic flow chart of a method for predicting the life of a fuel cell bipolar plate coating provided in an embodiment of the present application.

[0033] like Figure 1 As shown, the fuel cell bipolar plate coating life prediction method includes the following steps:

[0034] Step 101, under the fuel cell reference current density, based on the ratio of the voltage attenuation caused by the increase in contact resistance of the fuel cell bipolar plate coating to the initial state voltage, determine the termination condition of the life test of the fuel cell bipolar plate coating; the fuel cell reference current density is used to characterize the current density corresponding to the first volt value when the average voltage per cell of the fuel cell is.

[0035] As an implementation method, a bipolar plate coating durability index is selected, and the termination condition of the bipolar plate coating life test is set according to the ratio of the voltage attenuation caused by the increase in the contact resistance of the bipolar plate coating under the fuel cell reference current density to the initial state voltage.

[0036] In some embodiments, the first volt value is 0.7V, that is, the reference current density refers to the current density corresponding to the average voltage of each fuel cell of 0.7V. The reference current density of the fuel cell ranges from 1.8 to 2.0A / cm 2 .

[0037] In some embodiments, the fuel cell base current density is 2.0 A / cm 2 The termination condition of the life test of the fuel cell bipolar plate coating is that the voltage decay accounts for more than 10% of the initial state voltage of the fuel cell. In other words, the test is terminated when the voltage decay caused by the increase in the contact resistance of the bipolar plate accounts for more than 10% of the initial state voltage.

[0038] It should be noted that according to Ohm's law, the contact resistance of the fuel cell bipolar plate increases by more than 17.5mΩ·cm 2 In other words, the termination condition of the fuel cell bipolar plate coating life test can also be that the increase in the contact resistance of the fuel cell bipolar plate compared to the initial state exceeds 17.5mΩ·cm 2 .

[0039] Step 102, based on the accelerated corrosion test platform and the cathode potential under the simulated normal operation condition of the fuel cell, an offline real life test is performed on the fuel cell bipolar plate coating to obtain a first corresponding relationship between the contact resistance and the real test time.

[0040] It should be noted that before testing, an accelerated corrosion test platform needs to be built.

[0041] In some embodiments, the accelerated corrosion test platform includes an electrochemical workstation, a central control machine, a corrosion test cell and an oil bath pot, the corrosion test cell is used to contain the corrosive liquid and the fuel cell bipolar plate sample to be tested, the corrosion test cell is provided with an air inlet and an air outlet, the corrosion test cell is placed in the oil bath pot, the corrosion test cell is connected to the electrochemical workstation through a three-electrode system, and the electrochemical workstation is connected to the central control machine. Preferably, the corrosion test cell is a five-port corrosion test cell. During the test, the fuel cell bipolar plate sample to be tested is placed in the corrosive liquid through the working electrode fixture.

[0042] In some embodiments, the cathode potential range of the simulated fuel cell under normal operating conditions is 0.74V to 0.84V vs. SHE, preferably 0.84V vs. SHE. The corrosion environment temperature range provided by the accelerated corrosion test platform is 75 to 90°C, preferably 80°C; the corrosion medium in the corrosion solution includes H2SO4 and F ions, the pH value of H2SO4 ranges from 2 to 4, preferably pH=3; the concentration range of F ions is 0.01 to 10ppm, preferably 5ppm.

[0043] In this embodiment, the first corresponding relationship between the contact resistance and the actual test time is expressed as R1=f(t1), that is, based on the corresponding cathode potential under the normal operating conditions of the simulated fuel cell, the bipolar plate coating is subjected to offline life measurement, and the functional relationship between the contact resistance R1 of the bipolar plate coating and the test time t1 is obtained: R1=f(t1).

[0044] For example, when performing an offline real life test, the contact resistance of the coating can be measured every 500 hours, and the actual measurement time t1 is from 11500 hours. Figure 2 In order to prevent the corrosion liquid from volatilizing during the long-term test and causing the simulated environment to be inaccurate, the corrosion liquid needs to be replaced every 7 days.

[0045] Step 103, based on the adjusted test conditions of the accelerated corrosion test platform, perform an offline accelerated life test on the fuel cell bipolar plate coating to obtain a second corresponding relationship between contact resistance and accelerated test time and a first accelerated test duration corresponding to when the offline accelerated life test reaches a termination condition.

[0046] In some embodiments, the offline accelerated life test also uses a constant potential polarization test. During the constant potential polarization test, air or oxygen is introduced into the corrosive liquid at a ventilation rate of 10 to 30 ml / min.

[0047] In some embodiments, the first accelerated test duration of the offline accelerated life test is controlled by an acceleration factor, and the acceleration factor includes one or more of increasing the test potential, lowering the pH value, and increasing the test environment temperature, wherein the increased test potential ranges from 1 to 2 Vvs. SHE, the lowered pH value ranges from 0 to 1, and the increased test environment temperature ranges from 90 to 100°C.

[0048] It can be understood that by controlling the acceleration factor, the bipolar plate coating is subjected to an offline accelerated life test. The time used for the offline accelerated life test is controlled by the acceleration factor. The faster the test acceleration is increased with the acceleration factor, the shorter the first accelerated test time is.

[0049] In some embodiments, the constant potential polarization potential selected for the offline accelerated life test is 1.4V.

[0050] In this embodiment, the second corresponding relationship between the contact resistance and the accelerated test time is expressed as R2=h(t2), that is, by changing the test conditions, the bipolar plate coating is subjected to an offline accelerated life test, and the functional relationship between the contact resistance R2 of the bipolar plate coating and the test time t2 is obtained as: R2=h(t2).

[0051] For example, when performing an offline accelerated life test, the contact resistance of the coating may be measured every 24 hours. Figure 2 shown.

[0052] Step 104: Obtain a mapping relationship between the real test time and the accelerated test time based on the first corresponding relationship and the second corresponding relationship.

[0053] As an implementation method, based on a fixed reference current, a mapping relationship between the real test time t1 and the accelerated test time t2 is established, and the mapping relationship is expressed as follows:

[0054] t2=g(t1).

[0055] It can be understood that the voltage attenuation caused by the increase in contact resistance of the fuel cell bipolar plate coating is used as the termination condition of the life test of the fuel cell bipolar plate coating. The voltage attenuation caused by the offline accelerated life test and the offline real life test should be the same. According to the formula I*R=V, since the current is a fixed reference current, f(t1)=R1=R2=h(t2), that is, the functional relationship between the accelerated test time t2 and the real test time t1 is established: t2=g(t1).

[0056] Step 105 , based on the first accelerated test duration and the mapping relationship between the actual test time and the accelerated test time, obtain a prediction result of the fuel cell bipolar plate coating life.

[0057] It can be understood that the life of the bipolar plate coating is predicted based on the mapping relationship between the first accelerated test time required for the bipolar plate coating to reach the end of life in the offline accelerated life test and the time taken for the bipolar plate coating to reach the end of life under normal operating conditions.

[0058] For example, Figure 2 As shown, the fuel cell bipolar plate coating life prediction method of the present application can predict that the actual coating life is 10,000 hours through an accelerated test evaluation of about 92 hours.

[0059] The fuel cell bipolar plate coating life prediction method of the present application judges the bipolar plate coating failure index by the increase of contact resistance, performs offline actual measurement and offline accelerated test on the bipolar plate coating under the simulated fuel cell operating conditions, and on the basis of obtaining the time required for the accelerated life test to reach the end of life, predicts the life of the bipolar plate coating according to the mapping relationship between the time required for the bipolar plate coating to reach the end of life in the offline accelerated life test and the time taken for the bipolar plate coating to reach the end of life under normal operating conditions; thereby achieving a prediction result with the measured life of the coating as a reference, which is more accurate than that obtained with the stack life as a reference; at the same time, using the offline accelerated life test instead of the offline life measurement can quickly predict the life of the coating; using an electrochemical workstation to test the coating through a three-electrode system greatly reduces the test cost and improves the test efficiency compared with the prior art; thereby achieving a simple, efficient and accurate prediction of the life of the fuel cell bipolar plate coating, which is conducive to the rapid iteration of coating process research and development.

[0060] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0061] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0062] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for predicting the life of a fuel cell bipolar plate coating, characterized in that: The following steps are involved: Under the fuel cell reference current density, the termination condition of the life test of the fuel cell bipolar plate coating is determined based on the proportion of the voltage attenuation caused by the increase in the contact resistance of the fuel cell bipolar plate coating to the initial state voltage; the fuel cell reference current density is used to characterize the current density corresponding to the first volt value when the average voltage per cell of the fuel cell is; Based on the accelerated corrosion test platform and the cathode potential under the simulated normal operating conditions of the fuel cell, an offline real life test is performed on the fuel cell bipolar plate coating to obtain a first corresponding relationship between the contact resistance and the real test time; Based on the adjusted test conditions of the accelerated corrosion test platform, an offline accelerated life test is performed on the fuel cell bipolar plate coating to obtain a second corresponding relationship between the contact resistance and the accelerated test time and a first accelerated test duration corresponding to when the offline accelerated life test reaches the termination condition; Based on the first corresponding relationship and the second corresponding relationship, obtaining a mapping relationship between the real test time and the accelerated test time; Based on the first accelerated test duration and the mapping relationship between the actual test time and the accelerated test time, a prediction result of the fuel cell bipolar plate coating life is obtained.

2. The method according to claim 1, characterized in that The first volt value is 0.7V, and the fuel cell reference current density is 1.8-2.0A / cm 2 .

3. The method according to claim 1, characterized in that The termination condition of the life test of the fuel cell bipolar plate coating is that the voltage attenuation accounts for a proportion of the initial state voltage of the fuel cell that is greater than 10%.

4. The method according to claim 1, characterized in that: The accelerated corrosion testing platform includes an electrochemical workstation, a central control machine, a corrosion testing cell and an oil bath pot. The corrosion testing cell is used to contain a corrosive liquid and a fuel cell bipolar plate sample to be tested. The corrosion testing cell is provided with an air inlet and an air outlet. The corrosion testing cell is placed in the oil bath pot. The corrosion testing cell is connected to the electrochemical workstation through a three-electrode system, and the electrochemical workstation is connected to the central control machine.

5. The method according to claim 4, characterized in that The offline real life test and the offline accelerated life test both adopt constant potential polarization test. During the constant potential polarization test, air or oxygen is introduced into the corrosion liquid at a ventilation rate of 10 to 30 ml / min.

6. The method according to claim 4, characterized in that The corrosion environment temperature provided by the accelerated corrosion test platform is 75-90°C, preferably 80°C; the corrosive medium in the corrosive solution includes H2SO4 and F ions, the pH value of H2SO4 ranges from 2 to 4, preferably pH=3; the concentration range of F ions is 0.01-10ppm, preferably 5ppm.

7. The method according to claim 6, characterized in that The first accelerated test duration of the offline accelerated life test is controlled by an acceleration factor, and the acceleration factor includes one or more of increasing the test potential, decreasing the pH value, and increasing the test environment temperature, wherein the increased test potential ranges from 1 to 2 V vs. SHE, the decreased pH value ranges from 0 to 1, and the increased test environment temperature ranges from 90 to 100°C.

8. The method according to claim 5, characterized in that The constant potential polarization potential selected for the offline accelerated life test is 1.4V.

9. The method according to claim 1, characterized in that: The cathode potential of the simulated fuel cell under normal operating conditions is 0.74V to 0.84V vs. SHE, preferably 0.84V.

10. The method according to claim 1, characterized in that The obtaining, based on the first corresponding relationship and the second corresponding relationship, a mapping relationship between the real test time and the accelerated test time includes: The first corresponding relationship is expressed as R1=f(t1); The second corresponding relationship is expressed as R2=h(t2); Based on a fixed reference current, a mapping relationship between the real test time t1 and the accelerated test time t2 is established, and the mapping relationship is expressed as follows: t2=g(t1).

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