Fuel cell bipolar plate aging life prediction method based on multi-temperature-zone correction

Abstract

The invention relates to the technical field of fuel cell testing, in particular to a fuel cell bipolar plate aging life prediction method based on multi-temperature-zone correction, and the method comprises the steps: carrying out a bench cycle endurance test on a sample fuel cell bipolar plate, and carrying out the fitting to obtain a first contact resistance formula and a first corrosion current density formula; performing an off-line test, and fitting to obtain a second corrosion current density formula, a third corrosion current density formula, a fourth corrosion current density formula and a contact resistance formula; further constructing a first correlation factor formula and a second correlation factor formula; and acquiring temperature distribution of each coordinate point in the fuel cell bipolar plate to be predicted, and calculating to obtain a correlation factor between the life of the fuel cell bipolar plate to be predicted on the electric pile layer and the off-line test life. According to the method, the prediction relation with the service life of the bipolar plate after the online test, the relevance between the corrosion rate and the working temperature and the relevance between the offline test and the online electric pile durability test are quantitatively established through the offline bipolar plate test, and the research and development cost is saved.

Description

Technical Field

[0001] The present application relates to the field of fuel cell testing technology, and in particular to a method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction. Background Art

[0002] Durability is a necessary prerequisite for the large-scale commercialization of fuel cells. As the core component of the fuel cell stack, the fuel cell bipolar plate plays a core function of heat conduction, electrical conduction, gas distribution, etc. However, since fuel cells work in an acidic and high-temperature electrochemical environment, the corrosion resistance of the bipolar plate is the most important factor affecting its life.

[0003] During the operation of the fuel cell, the temperature inside the battery is not evenly distributed due to the different reaction heat generation, the temperature difference of the cooling channel, the difference in contact resistance, etc. Therefore, the corrosion or aging decay rate of each part of the battery is also different. Therefore, this local difference will cause the short board effect, making the battery life design index deviate from the ideal value. Summary of the invention

[0004] To achieve the above objectives, this application provides the following technical solutions: According to a first aspect of the present invention, the present invention claims a method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction, comprising: Performing a bench cycle endurance test on a sample fuel cell bipolar plate, and fitting to obtain a first contact resistance formula and a first corrosion current density formula of the sample fuel cell bipolar plate; Conducting an offline test on a sample fuel cell bipolar plate, and fitting to obtain a second corrosion current density formula, a second contact resistance formula, a third corrosion current density formula, a third contact resistance formula, a fourth corrosion current density formula, and a fourth contact resistance formula of the sample fuel cell bipolar plate; Constructing a first correlation factor formula and a second correlation factor formula according to the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas; The temperature distribution of each coordinate point inside the bipolar plate of the fuel cell to be predicted is obtained, and the correlation factor between the life of the bipolar plate of the fuel cell to be predicted at the stack level and the offline test life is calculated.

[0005] Furthermore, the bench cycle endurance test is performed on the sample fuel cell bipolar plate to fit the first contact resistance formula of the sample fuel cell bipolar plate, and further includes: After the sample fuel cell bipolar plates are assembled into a first fuel cell stack, a bench cycle endurance test is carried out, and the set operating temperature and the set operating voltage are recorded. The resistance change data is recorded once every preset time under the same steady-state conditions, and the resistance change data is polynomially fitted with the preset time to obtain the first contact resistance formula.

[0006] Furthermore, the bench cycle endurance test is performed on the sample fuel cell bipolar plate to fit the first corrosion current density formula of the sample fuel cell bipolar plate, and further includes: After assembling the sample fuel cell bipolar plates into a second stack, a bench cycle endurance test is performed, and the set operating temperature and set working voltage are recorded. The bipolar plates are taken out at preset intervals for corrosion current density testing to obtain a first corrosion current density ， Will Said The first corrosion current density and the preset time are subjected to data polynomial fitting to obtain a first corrosion current density formula.

[0007] Furthermore, the off-line test of the sample fuel cell bipolar plate is performed to fit the second corrosion current density formula, the second contact resistance formula, the third corrosion current density formula, the third contact resistance formula, the fourth corrosion current density formula, and the fourth contact resistance formula of the sample fuel cell bipolar plate, and further includes: Performing an off-line test of the corrosion current density of the sample fuel cell bipolar plate at different temperatures, and recording the corrosion current density and contact resistance of the sample fuel cell bipolar plate at regular intervals; According to the second corrosion current density of the sample fuel cell bipolar plate, a second corrosion current density formula between different offline test temperatures is obtained by fitting; According to the second contact resistance of the sample fuel cell bipolar plate, a second contact resistance formula between different offline test temperatures is obtained by fitting; According to the third corrosion current density of the bipolar plate of the sample fuel cell, a third corrosion current density formula between different offline test times is obtained by fitting; According to the third contact resistance of the bipolar plate of the sample fuel cell, a third contact resistance formula between different offline test times is obtained by fitting; Furthermore, a first correlation factor formula is constructed based on the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas, further comprising: According to the second corrosion current density formula, a ratio of the second corrosion current density at the off-line test temperature to the set operating temperature of the bench cycle endurance test is obtained as a first temperature correction factor; A first correlation factor formula is constructed according to the first temperature correction factor, the third corrosion current density and the first corrosion current density.

[0008] Furthermore, a second correlation factor formula is constructed based on the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas, and further includes: According to the second contact resistance formula, a second contact resistance ratio at the offline test temperature and the set operating temperature of the bench cycle endurance test is obtained as a second temperature correction factor; A second correlation factor formula is constructed according to the second temperature correction factor, the third contact resistance and the first contact resistance.

[0009] Furthermore, the step of obtaining the temperature distribution of each coordinate point inside the bipolar plate of the fuel cell to be predicted and calculating the correlation factor between the life of the bipolar plate of the fuel cell to be predicted at the stack level and the offline test life also includes: The interior of the fuel cell bipolar plate to be predicted is divided into a plurality of calculation areas, and if a coordinate system is established with the length direction of the battery as the x direction and the width direction as the y direction, the temperature distribution data of the coordinate points of each calculation area are correspondingly obtained; Calculating and obtaining a first temperature correction factor and a second temperature correction factor of each coordinate point of the bipolar plate of the fuel cell to be predicted; The first correlation factor and the second correlation factor of each coordinate point of the bipolar plate of the fuel cell to be predicted are obtained jointly, and an average value is calculated based on the maximum value and the minimum value of the first correlation factor and the second correlation factor of each coordinate point.

[0010] Furthermore, the calculation to obtain the first temperature correction factor and the second temperature correction factor of each coordinate point of the bipolar plate of the fuel cell to be predicted also includes: Calculating the second corrosion current density of each coordinate point of the fuel cell bipolar plate to be predicted at the corresponding temperature according to the second corrosion current density formula; Calculating the second contact resistance of each coordinate point of the bipolar plate of the fuel cell to be predicted at the corresponding temperature according to the second contact resistance formula; Obtaining a second corrosion current density at a set operating temperature of a bench cycle endurance test, and obtaining a first temperature correction factor of the fuel cell bipolar plate to be predicted in combination with the second corrosion current density of each coordinate point of the fuel cell bipolar plate to be predicted at a corresponding temperature; The second contact resistance at the set operating temperature of the bench cycle endurance test is obtained, and the second temperature correction factor of the bipolar plate of the fuel cell to be predicted is obtained by combining the second contact resistance of each coordinate point of the bipolar plate of the fuel cell to be predicted at the corresponding temperature.

[0011] The present application relates to the field of fuel cell testing technology, and in particular to a method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction. A bench cycle endurance test is performed on a sample fuel cell bipolar plate, and a first contact resistance formula and a first corrosion current density formula are obtained by fitting; an offline test is performed, and the second, third, and fourth corrosion current density formulas and contact resistance formulas are obtained by fitting; a first correlation factor formula and a second correlation factor formula are further constructed; the temperature distribution of each coordinate point inside the fuel cell bipolar plate to be predicted is obtained, and the correlation factor between the life of the fuel cell bipolar plate to be predicted at the stack level and the offline test life is calculated. The present invention quantitatively establishes a predictive relationship with the bipolar plate life after the online test, the correlation between the corrosion rate and the operating temperature, and the correlation between the offline test and the online stack durability test through the offline bipolar plate test, thereby saving R&D costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A flowchart of a method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction as claimed in an embodiment of the present application; Figure 2 A temperature distribution diagram inside a fuel cell bipolar plate according to a fuel cell bipolar plate aging life prediction method based on multi-temperature zone correction is provided as claimed in an embodiment of the present application. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0014] The terms "first", "second" and "third" in this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second" and "third" can explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. All directional indications (such as up, down, left, right, front, back...) in the embodiments of this application are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0015] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0016] The corrosion resistance of bipolar plates is usually evaluated by electrochemical corrosion current density test. The corrosion current density is used to judge the corrosion resistance of the coating. The lower the corrosion current density, the stronger the corrosion resistance of the coating. At the same time, the longer the low corrosion current density is maintained, the lower the corrosion current density. However, the corrosion current density test is closely related to temperature. Generally, the higher the temperature, the faster the corrosion rate. Fuel cells also often work in the range of 60~90℃, and the corrosion rates in different temperature ranges are different.

[0017] The life of a fuel cell stack is measured in real life through a bench durability cycle test. The actual test time is usually several thousand hours, which will bring extremely high time and economic costs. The starting point of this application is to quantitatively establish a predictive relationship between the life of the bipolar plate after the online test through the offline bipolar plate test, thereby saving R&D costs.

[0018] According to the first embodiment of the present invention, the present invention claims a method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction, referring to Figure 1 ,include: Performing a bench cycle endurance test on a sample fuel cell bipolar plate, and fitting to obtain a first contact resistance formula and a first corrosion current density formula of the sample fuel cell bipolar plate; Conducting an offline test on a sample fuel cell bipolar plate, and fitting to obtain a second corrosion current density formula, a second contact resistance formula, a third corrosion current density formula, a third contact resistance formula, a fourth corrosion current density formula, and a fourth contact resistance formula of the sample fuel cell bipolar plate; Constructing a first correlation factor formula and a second correlation factor formula according to the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas; The temperature distribution of each coordinate point inside the bipolar plate of the fuel cell to be predicted is obtained, and the correlation factor between the life of the bipolar plate of the fuel cell to be predicted at the stack level and the offline test life is calculated.

[0019] Furthermore, the bench cycle endurance test is performed on the sample fuel cell bipolar plate to fit the first contact resistance formula of the sample fuel cell bipolar plate, and further includes: After the sample fuel cell bipolar plates are assembled into a first fuel cell stack, a bench cycle endurance test is carried out, and the set operating temperature and the set operating voltage are recorded. The resistance change data is recorded once every preset time under the same steady-state conditions, and the resistance change data is polynomially fitted with the preset time to obtain the first contact resistance formula.

[0020] In this embodiment, the sample fuel cell bipolar plates are assembled into a stack M and then subjected to a bench cycle endurance test, and the set operating temperature Ka and the set operating voltage Va are recorded, and the resistance change data R1 is recorded once at the same time under the same steady-state conditions. The first contact resistance formula is obtained by fitting the data polynomial of R1 and the operating time t.

[0021] R1(t)=a1·t 4 +b1·t 3 +c1·t 2 +d1·t+e1 (1) Among them, a1, b1, c1, d1, e1 are the coefficients obtained by fitting.

[0022] Furthermore, the bench cycle endurance test is performed on the sample fuel cell bipolar plate to fit the first corrosion current density formula of the sample fuel cell bipolar plate, and further includes: After assembling the sample fuel cell bipolar plates into a second stack, a bench cycle endurance test is performed, and the set operating temperature and set working voltage are recorded. The bipolar plates are taken out at preset intervals for corrosion current density testing to obtain a first corrosion current density ， Will Said The first corrosion current density and the preset time are subjected to data polynomial fitting to obtain a first corrosion current density formula.

[0023] In this embodiment, the sample fuel cell bipolar plates are assembled into a stack N and then subjected to a bench cycle endurance test, and the set operating temperature Ka and the set operating voltage Va are recorded, and the bipolar plates are taken out at the same intervals for corrosion current density testing to obtain a first corrosion current density I 1. I 1 and the running time t are fitted with a data polynomial to obtain the first corrosion current density formula.

[0024] I 1(t)=a2·t 4 +b2·t 3 +c2·t 2 +d2·t+e2 (2) Among them, a2, b2, c2, d2, e2 are the coefficients obtained by fitting.

[0025] Furthermore, the off-line test of the sample fuel cell bipolar plate is performed to fit the second corrosion current density formula, the second contact resistance formula, the third corrosion current density formula, the third contact resistance formula, the fourth corrosion current density formula, and the fourth contact resistance formula of the sample fuel cell bipolar plate, and further includes: Performing an off-line test of the corrosion current density of the sample fuel cell bipolar plate at different temperatures, and recording the corrosion current density and contact resistance of the sample fuel cell bipolar plate at regular intervals; According to the second corrosion current density of the sample fuel cell bipolar plate, a second corrosion current density formula between different offline test temperatures is obtained by fitting; According to the second contact resistance of the sample fuel cell bipolar plate, a second contact resistance formula between different offline test temperatures is obtained by fitting; According to the third corrosion current density of the bipolar plate of the sample fuel cell, a third corrosion current density formula between different offline test times is obtained by fitting; According to the third contact resistance of the bipolar plate of the sample fuel cell, a third contact resistance formula between different offline test times is obtained by fitting; In this embodiment, the off-line corrosion current density of the bipolar plate is tested at different temperatures K, and the corrosion current density is recorded and the contact resistance is re-measured at regular intervals.

[0026] The second corrosion current density of the bipolar plate I 2 Establish the second corrosion current density formula between different off-line test temperatures K.

[0027] I 2(K)=a3·K 4 +b3·K 3 +c3·K 2 +d3·K+e3 (3) Among them, a3, b3, c3, d3, e3 are the coefficients obtained by fitting.

[0028] The second contact resistance of the bipolar plate R 2 Establish the second contact resistance formula between different off-line test temperatures K.

[0029] R 2(K)=a4·K 4 +b4·K 3 +c4·K 2 +d4·K+e4 (4) Among them, a4, b4, c4, d4, e4 are the coefficients obtained by fitting.

[0030] The third corrosion current density of the bipolar plate I 3 Establish the third corrosion current density formula between different offline test times T.

[0031] I 3(T)=a5·T 4 +b5·T 3 +c5·T 2 +d5·T+e5 (5) Among them, a5, b5, c5, d5, e5 are the coefficients obtained by fitting.

[0032] The third contact resistance of the bipolar plate R 3. Establish a third contact resistance formula between different offline test times T.

[0033] R 3(T)=a6·T 4 +b6·T 3 +c6·T 2 +d6·T+e6 (6) Among them, a6, b6, c6, d6, e6 are the coefficients obtained by fitting.

[0034] Furthermore, a first correlation factor formula is constructed based on the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas, further comprising: According to the second corrosion current density formula, a ratio of the second corrosion current density at the off-line test temperature to the set operating temperature of the bench cycle endurance test is obtained as a first temperature correction factor; A first correlation factor formula is constructed according to the first temperature correction factor, the third corrosion current density and the first corrosion current density.

[0035] In this embodiment, a first correlation factor G1 is established between the bipolar plate durability test and the offline test at the stack level, which is connected by the corrosion current density.

[0036] (7); Where ε1 is the first temperature correction factor.

[0037] Furthermore, a second correlation factor formula is constructed based on the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas, and further includes: According to the second contact resistance formula, a second contact resistance ratio at the offline test temperature and the set operating temperature of the bench cycle endurance test is obtained as a second temperature correction factor; A second correlation factor formula is constructed according to the second temperature correction factor, the third contact resistance and the first contact resistance.

[0038] Among them, in this embodiment, a second correlation factor G2 of the bipolar plate connected with the contact resistance in the endurance test and the offline test at the stack level is established.

[0039] (8); Where ε2 is the second temperature correction factor.

[0040] Furthermore, the step of obtaining the temperature distribution of each coordinate point inside the bipolar plate of the fuel cell to be predicted and calculating the correlation factor between the life of the bipolar plate of the fuel cell to be predicted at the stack level and the offline test life also includes: The interior of the fuel cell bipolar plate to be predicted is divided into a plurality of calculation areas, and if a coordinate system is established with the length direction of the battery as the x direction and the width direction as the y direction, the temperature distribution data of the coordinate points of each calculation area are correspondingly obtained; Calculating and obtaining a first temperature correction factor and a second temperature correction factor of each coordinate point of the bipolar plate of the fuel cell to be predicted; The first correlation factor and the second correlation factor of each coordinate point of the bipolar plate of the fuel cell to be predicted are obtained jointly, and an average value is calculated based on the maximum value and the minimum value of the first correlation factor and the second correlation factor of each coordinate point.

[0041] Among them, in this embodiment, if Figure 2As shown in the figure, by bench testing, the stack is divided into zones and multiple thermocouples are used to test the temperature distribution inside the fuel cell. Since the temperature points inside the battery are different, the aging attenuation is also different. Therefore, if the battery is divided into CA calculation zones, such as Figure 2 As shown by the black dots in the middle, if the coordinate system is established with the length direction of the battery as the x direction and the width direction as the y direction, when n=9 (9 points in the x direction) and y=4 (4 points in the y direction), CA=36, then the data at 36 coordinate points can be obtained, namely: Temperature distribution data matrix K[xy]: (9)

[0042] Furthermore, the calculation to obtain the first temperature correction factor and the second temperature correction factor of each coordinate point of the bipolar plate of the fuel cell to be predicted also includes: Calculating the second corrosion current density of each coordinate point of the fuel cell bipolar plate to be predicted at the corresponding temperature according to the second corrosion current density formula; Calculating the second contact resistance of each coordinate point of the bipolar plate of the fuel cell to be predicted at the corresponding temperature according to the second contact resistance formula; Obtaining a second corrosion current density at a set operating temperature of a bench cycle endurance test, and obtaining a first temperature correction factor of the fuel cell bipolar plate to be predicted in combination with the second corrosion current density of each coordinate point of the fuel cell bipolar plate to be predicted at a corresponding temperature; The second contact resistance at the set operating temperature of the bench cycle endurance test is obtained, and the second temperature correction factor of the bipolar plate of the fuel cell to be predicted is obtained by combining the second contact resistance of each coordinate point of the bipolar plate of the fuel cell to be predicted at the corresponding temperature.

[0043] In this embodiment, the temperature K at each coordinate is substituted into the second corrosion current density of the corresponding bipolar plate. I 2： (10);

[0044] Substituting the temperature K at each coordinate above into the corresponding second contact resistance R of the bipolar plate 2： (11)

[0045] Substitute (10) I2 and the set value Ka into formula (3) to obtain I2(Ka), and then substitute into formula (7) to obtain the first temperature correction factor ε1; (12)

[0046] Substitute R2 in formula (11) and R2(Ka) obtained by substituting the set value Ka into formula (4) into formula (8) to obtain the second temperature correction factor ε2; (13)

[0047] Furthermore, the first potential correction factor and the second potential correction factor of each coordinate point of the bipolar plate of the fuel cell to be predicted are calculated, and further include: Calculating the fourth corrosion current density at the corresponding voltage at each coordinate point of the bipolar plate of the fuel cell to be predicted according to the fourth corrosion current density formula; Calculating the fourth contact resistance of each coordinate point of the bipolar plate of the fuel cell to be predicted at the corresponding voltage according to the fourth contact resistance formula; Finally, equations (2), (5), and (12) are substituted into equation (7) to establish the first correlation factor G1 between the bipolar plate durability test and the offline test at the stack level, which is connected by the corrosion current density; (14)

[0048] Substituting equations (1), (6), and (13) into equation (8), the second correlation factor G2 of the bipolar plate connected with contact resistance in the endurance test and offline test at the stack level is established; (15).

[0049] The following is an actual experimental test case: After the fuel cell bipolar plates are assembled into a stack M, a bench cycle endurance test is carried out, and the operating temperature Ka=70°C and the operating voltage Va=0.64V are set, and the resistance change data R1 is recorded once at the same time under the same steady-state conditions. The correlation formula is obtained by fitting the data polynomial between R1 and the operating time t.

[0050] R1(t)=a1·t 4 +b1·t 3 +c1·t 2 +d1·t+e1 (16) Among them, a1, b1, c1, d1, e1 are the coefficients obtained by fitting.

[0051] Table 1 Relationship between running time and R1 Running time t (h) Contact resistance R1 (mΩ) 100 5.64 200 5.64 300 5.86 400 5.86 500 6.08 600 6.08 700 6.08 800 6.3 900 6.52 1000 6.74 1100 6.98 1200 7.18 1300 7.4 1400 7.4 1500 7.62 1600 7.84 1700 8.06 1800 8.28 1900 8.5 2000 8.72 Referring to Table 1, a data polynomial fitting is performed on R1 and the running time t to obtain the correlation equation (16): At this time, a1=1e -13 ; b1 = -7e -10 ; c1 = 2e -06 ;d1=-0.0001;e1=5.6533.

[0052] To ensure accuracy, the fitting process retains 10 decimal places.

[0053] At this time, the correlation equation (16) is R1(t)=1e -13 ·t 4 -7e -10 ·t 3 +2e -06 t 2 -0.0001·t+5.6533; After the fuel cell bipolar plates are assembled into a stack N, a bench cycle durability test is carried out, and Ka=70℃ and the working voltage Va=0.64V are set. The bipolar plates are taken out at the same intervals for corrosion current density test to obtain corrosion current density data. I 1. I 1 and the running time t are fitted with a data polynomial to obtain the correlation equation.

[0054] I 1 (t) = a2 t 4 +b2·t 3 +c2·t 2 +d2·t+e2 (17); Among them, a2, b2, c2, d2, e2 are the coefficients obtained by fitting.

[0055] Table 2 Running time and I 1 Relationship table Running time t (h) <![CDATA[Corrosion current density I 1 (μA / cm 2 )]]> 100 0.28 200 0.28 300 0.29 400 0.29 500 0.30 600 0.31 700 0.32 800 0.32 900 0.33 1000 0.34 1100 0.35 1200 0.36 1300 0.37 1400 0.37 1500 0.38 1600 0.38 1700 0.39 1800 0.39 1900 0.40 2000 0.41 Refer to Table 2. I 1 and the running time t are fitted with a data polynomial to obtain the correlation equation. To ensure accuracy, the fitting process retains 10 decimal places.

[0056] At this time, a2=2e -14 ; b2 = -1e -10 ; c2 = 2e -07 ; d2 = -3e -05 ; e2=0.2814.

[0057] At this time, the correlation (17) is I 1 (t)=2e -14 ·t 4 -1e -10 t 3 +2e -07 t 2 -3e -05 ·t+0.2814.

[0058] Offline corrosion current density of bipolar plates I 2 Establish the correlation between different offline test temperatures K.

[0059] I 2(K)=a3·K 4 +b3·K 3 +c3·K 2 +d3·K+e3 (18); Among them, a3, b3, c3, d3, e3 are the coefficients obtained by fitting.

[0060] Table 3 Offline test temperature and I 2 Relationship Table Different offline test temperatures K (℃) <![CDATA[Corrosion current density I2 (μA / cm 2 ).]]> 30 0.27 40 0.29 50 0.31 60 0.34 70 0.38 80 0.43 Referring to Table 3, a correlation equation is obtained by performing data polynomial fitting between different offline test temperatures K and corrosion current density I2.

[0061] To ensure accuracy, the fitting process retains 10 decimal places.

[0062] At this time, a3=-2e -08 ; b3 = 5e -06 ; c3=-0.0004; d3=0.0149; e3=0.063.

[0063] At this time, the correlation (18) is: I 2(K)=-2e -08 ·K 4 +5e -06 ·K 3 -0.0004·K 2 +0.0149·K+0.063; Referring to Table 4, a correlation equation between the bipolar plate offline contact resistance R2 and different offline test temperatures K is established.

[0064] R2(K)=a4·K 4 +b4·K 3 +c4·K 2 +d4·K+e4 (19); Among them, a4, b4, c4, d4, e4 are the coefficients obtained by fitting.

[0065] Table 4 Relationship between offline test temperature and R2 Different offline test temperatures K (℃) <![CDATA[Contact resistance R2 (mΩ)]]> 30 5.65 40 6.08 50 6.52 60 7.22 70 8.31 80 9.06 To ensure accuracy, the coefficients are rounded to 10 decimal places after fitting.

[0066] At this time, a4=-2e -06 ; b4=0.0004; c4=-0.0328; d4=1.0857; e4=-7.5002.

[0067] At this time, the correlation equation (19) is R2(K)=-2e -06 ·K 4 +0.0004·K 3 -0.0328·K 2 +1.0857·K-7.5002; Referring to Table 5, the off-line corrosion current density of the bipolar plate I 3. Establish the correlation between different offline test times T.

[0068] I 3 (T) = a5·T 4 +b5·T 3 +c5·T 2 +d5·T+e5 (20); Among them, a5, b5, c5, d5, e5 are the coefficients obtained by fitting.

[0069] Table 5 Different offline test time and I 3 Relationship Table Different offline test time T (h) <![CDATA[Corrosion current density I 3 (μA / cm 2 )]]> 10 0.29 20 0.29 30 0.3 40 0.3 50 0.31 60 0.31 70 0.32 80 0.33 90 0.34 100 0.35 110 0.36 120 0.37 130 0.38 140 0.40 150 0.42 160 0.45 170 0.48 180 0.51 190 0.55 200 0.60 At this time, a5=3e -10 ; b5 = -8e -08 ; c2 = 9e -06 ; d2 = 8e -05 ; e2=0.2876. (To ensure accuracy, the coefficients after fitting are retained to 10 decimal places) At this time, the correlation (20) is I 3 (T)=3e -10 ·T 4 -8e -8 ·T 3 +9e -06 ·T 2 +8e -05 ·T+0.2876; Referring to Table 6, a correlation equation between the bipolar plate offline contact resistance R3 and different offline test times T is established.

[0070] R3(T)=a6·T 4 +b6·T 3 +c6·T 2 +d6·T+e6 (21); Among them, a6, b6, c6, d6, e6 are the coefficients obtained by fitting.

[0071] Table 6 Relationship between different offline test time and R3 Different offline test time T (h) <![CDATA[Bipolar plate off-line contact resistance R3 (mΩ)]]> 10 5.62 20 5.62 30 5.81 40 5.81 50 6.01 60 6.01 70 6.20 80 6.40 90 6.59 100 6.78 110 6.98 120 7.17 130 7.36 140 7.75 150 8.14 160 8.72 170 9.30 180 9.88 190 10.66 200 11.63 At this time, a6=6e -09; b6 = -1e -06 ;c6=0.0002; d6=0.0015; e6=5.5727.

[0072] At this time, the correlation formula (21) is R3(T)=6e -09 ·T 4 -1e -06 ·T 3 +0.0002·T 2 +0.0015·T+5.5727.

[0073] A correlation factor G1 between the bipolar plate durability test and offline test at the stack level was established based on the corrosion current density.

[0074]

[0075] where ε1 is a correction factor based on temperature.

[0076] A correlation factor G2 was established between the endurance test and the offline test of the bipolar plate at the stack level using contact resistance as the connection.

[0077]

[0078] where ε2 is a correction factor based on temperature.

[0079] The temperature distribution inside the fuel cell can be tested by experimental means. Since the temperature points inside the battery are different, the aging attenuation is also different. Therefore, if the inside of the battery is divided into CA calculation areas, a coordinate system is established with the battery length direction as the x direction and the width direction as the y direction.

[0080] When n=6 (6 points in the x direction) and y=4 (4 points in the y direction), CA=24, then the data at 24 coordinate points can be obtained, that is, the temperature distribution data K: 69.8 69.8 69.8 69.5 69.1 68.5 70.4 70.6 70.6 70.6 70.4 69.5 70.9 71.1 71.1 71.2 70.8 70.3 71.2 71.3 71.3 71.1 70.8 70.2 Substituting the temperature K at each coordinate above, the corresponding bipolar plate offline corrosion current density I2 can be obtained: 0.38 0.38 0.38 0.38 0.38 0.37 0.38 0.38 0.38 0.38 0.38 0.38 0.39 0.39 0.39 0.39 0.38 0.38 0.39 0.39 0.39 0.39 0.38 0.38 Substituting the temperature K at each coordinate above into the corresponding bipolar plate offline contact resistance R2: 8.27 8.27 8.27 8.24 8.20 8.14 8.34 8.36 8.36 8.36 8.34 8.24 8.39 8.41 8.41 8.42 8.38 8.33 8.42 8.43 8.43 8.41 8.38 8.32 Substitute equation I2 and the set value Ka = 70 to obtain I2(Ka), and substitute to obtain the temperature correction factor ε1; 1.00 1.00 1.00 1.00 0.99 0.98 1.01 1.01 1.01 1.01 1.01 1.00 1.01 1.02 1.02 1.02 1.01 1.01 1.02 1.02 1.02 1.02 1.01 1.01 Substitute R2 and the set value Ka into R2(Ka), and substitute into the temperature correction factor ε2; 1.00 1.00 1.00 0.99 0.99 0.98 1.00 1.01 1.01 1.01 1.00 0.99 1.01 1.01 1.01 1.01 1.01 1.00 1.01 1.01 1.01 1.01 1.01 1.00 In this embodiment, the endurance test of 1000h is selected as an example. When the endurance test time at the stack level is t=1200h and the offline test time is T=110h, I3(T)=I1(t)=0.36. Substitute the equations t, T, and ε1 to establish the correlation factor G1 between the endurance test and offline test of the bipolar plate at the stack level connected by the corrosion current density;

[0081] In this embodiment, the endurance test of 1000h is selected as an example. When the endurance test time at the stack level is t=1100h and the offline test time is T=110h, R3(T)=R1(t)=6.98. Substitute the equations t, T, and ε2 into the correlation factor G2 of the endurance test and offline test of the bipolar plate connected at the stack level with the contact resistance as the connection;

[0082] Therefore, matrices (14) and (15) are the correlation factors between the endurance test at the stack level and the offline endurance test when the endurance test is about 1000h.

[0083] The maximum value Gmax, the minimum value Gmin and the average value Gave are taken for G1 and G2 respectively, and then the correlation factor G between the final bipolar plate life at the stack level and the offline test life is obtained after averaging.

[0084] Gmax=11.12; Gmin=10.74; Gave=11.02. That is, the present application can not only obtain the distribution of attenuation amplitudes and correlation factors in different areas of the battery stack, but also obtain the maximum, minimum and average values ​​of the overall battery stack level endurance test and offline test correlation factors through the connection of corrosion current density and contact resistance.

[0085] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0086] In addition, each functional unit in each embodiment of the present application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of software functional units. The above is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of this application, or directly or indirectly used in other related technical fields, is also included in the patent protection scope of the present application.

[0087] The specific implementation methods of the invention are described in detail above, but they are only examples, and the present application is not limited to the specific implementation methods described above. For those skilled in the art, any equivalent modification or substitution of the invention is also within the scope of the present application, and therefore, the equalization, modification, and improvement made without departing from the spirit and principle of the present application should be included in the scope of the present application.

Claims

1. A method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction, characterized in that: include: Performing a bench cycle endurance test on a sample fuel cell bipolar plate, and fitting to obtain a first contact resistance formula and a first corrosion current density formula of the sample fuel cell bipolar plate; Conducting an offline test on a sample fuel cell bipolar plate, and fitting to obtain a second corrosion current density formula, a second contact resistance formula, a third corrosion current density formula, a third contact resistance formula, a fourth corrosion current density formula, and a fourth contact resistance formula of the sample fuel cell bipolar plate; Constructing a first correlation factor formula and a second correlation factor formula according to the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas; The temperature distribution of each coordinate point inside the bipolar plate of the fuel cell to be predicted is obtained, and the correlation factor between the life of the bipolar plate of the fuel cell to be predicted at the stack level and the offline test life is calculated.

2. The method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction according to claim 1, characterized in that: The bench cycle endurance test is performed on the sample fuel cell bipolar plate to obtain the first contact resistance formula of the sample fuel cell bipolar plate by fitting, and further includes: After the sample fuel cell bipolar plates are assembled into a first fuel cell stack, a bench cycle endurance test is carried out, and the set operating temperature and the set operating voltage are recorded. The resistance change data is recorded once every preset time under the same steady-state conditions, and the resistance change data is polynomially fitted with the preset time to obtain the first contact resistance formula.

3. The method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction according to claim 1, characterized in that: The bench cycle endurance test is performed on the sample fuel cell bipolar plate to obtain the first corrosion current density formula of the sample fuel cell bipolar plate by fitting, and further includes: After assembling the sample fuel cell bipolar plates into a second stack, a bench cycle endurance test is performed, and the set operating temperature and set working voltage are recorded. The bipolar plates are taken out at preset intervals for corrosion current density testing to obtain a first corrosion current density ， Will Said The first corrosion current density and the preset time are subjected to data polynomial fitting to obtain a first corrosion current density formula.

4. The method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction according to claim 1, characterized in that: The off-line test of the sample fuel cell bipolar plate is performed to fit the second corrosion current density formula, the second contact resistance formula, the third corrosion current density formula, the third contact resistance formula, the fourth corrosion current density formula, and the fourth contact resistance formula of the sample fuel cell bipolar plate, and further includes: Performing an off-line test of the corrosion current density of the sample fuel cell bipolar plate at different temperatures, and recording the corrosion current density and contact resistance of the sample fuel cell bipolar plate at regular intervals; According to the second corrosion current density of the sample fuel cell bipolar plate, a second corrosion current density formula between different offline test temperatures is obtained by fitting; According to the second contact resistance of the sample fuel cell bipolar plate, a second contact resistance formula between different offline test temperatures is obtained by fitting; According to the third corrosion current density of the bipolar plate of the sample fuel cell, a third corrosion current density formula between different offline test times is obtained by fitting; The third contact resistance formula between different offline test times is obtained by fitting the third contact resistance of the bipolar plate of the sample fuel cell.

5. The method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction according to claim 4, characterized in that: The first correlation factor formula is constructed according to the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas, and further includes: According to the second corrosion current density formula, a ratio of the second corrosion current density at the off-line test temperature to the set operating temperature of the bench cycle endurance test is obtained as a first temperature correction factor; A first correlation factor formula is constructed according to the first temperature correction factor, the third corrosion current density and the first corrosion current density.

6. The method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction according to claim 4, characterized in that: The second correlation factor formula is constructed according to the first contact resistance formula, the first corrosion current density formula, and a plurality of corrosion current density formulas and contact resistance formulas, and further includes: According to the second contact resistance formula, a second contact resistance ratio at the offline test temperature and the set operating temperature of the bench cycle endurance test is obtained as a second temperature correction factor; A second correlation factor formula is constructed according to the second temperature correction factor, the third contact resistance and the first contact resistance.

7. The method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction according to claim 1, characterized in that: The step of obtaining the temperature distribution of each coordinate point inside the bipolar plate of the fuel cell to be predicted and calculating the correlation factor between the life of the bipolar plate of the fuel cell to be predicted at the stack level and the life of the off-line test also includes: The interior of the fuel cell bipolar plate to be predicted is divided into a plurality of calculation areas, and if a coordinate system is established with the length direction of the battery as the x direction and the width direction as the y direction, the temperature distribution data of the coordinate points of each calculation area are correspondingly obtained; Calculating and obtaining a first temperature correction factor and a second temperature correction factor of each coordinate point of the bipolar plate of the fuel cell to be predicted; The first correlation factor and the second correlation factor of each coordinate point of the bipolar plate of the fuel cell to be predicted are obtained jointly, and an average value is calculated based on the maximum value and the minimum value of the first correlation factor and the second correlation factor of each coordinate point.

8. The method for predicting the aging life of a fuel cell bipolar plate based on multi-temperature zone correction according to claim 7, characterized in that: The calculation to obtain the first temperature correction factor and the second temperature correction factor of each coordinate point of the bipolar plate of the fuel cell to be predicted also includes: Calculating the second corrosion current density of each coordinate point of the fuel cell bipolar plate to be predicted at the corresponding temperature according to the second corrosion current density formula; Calculating the second contact resistance of each coordinate point of the bipolar plate of the fuel cell to be predicted at the corresponding temperature according to the second contact resistance formula; Obtaining a second corrosion current density at a set operating temperature of a bench cycle endurance test, and obtaining a first temperature correction factor of the fuel cell bipolar plate to be predicted in combination with the second corrosion current density of each coordinate point of the fuel cell bipolar plate to be predicted at a corresponding temperature; The second contact resistance at the set operating temperature of the bench cycle endurance test is obtained, and the second temperature correction factor of the bipolar plate of the fuel cell to be predicted is obtained by combining the second contact resistance of each coordinate point of the bipolar plate of the fuel cell to be predicted at the corresponding temperature.

Images