A method for detecting cathode fluid distribution in a proton exchange membrane fuel cell stack

Abstract

The application discloses a detection method for cathode fluid distribution of a proton exchange membrane fuel cell stack, which is characterized by utilizing the relationship between the characteristic frequency of the flow channel impedance and the stoichiometric ratio of the cathode fluid (f ch The linear correlation between 1 / ln(1-1 / λ) and 1 / ln(1-1 / λ) is used to determine the cathode fluid distribution of each cell in the stack. The detection method is simple, practical and effective. All parameters are extracted from the real-time measured electrochemical impedance spectrum, without the need for prior correction, which is of great significance for high consistency stack design and health state monitoring of each cell in the stack.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to a method for detecting the cathode fluid distribution in a proton exchange membrane fuel cell stack. Background Technology

[0002] Proton exchange membrane fuel cells are power generation devices that directly convert the chemical energy of fuel into electrical energy. They have advantages such as high energy conversion efficiency, high specific energy, and low pollution, and have broad application prospects in transportation equipment (including automobiles, ships, drones, etc.), portable mobile power sources, and stationary power stations.

[0003] A typical proton exchange membrane fuel cell (PEMFC) consists of electrodes with flow channels, an anode, an electrolyte, a cathode, and another electrode with flow channels, arranged sequentially. Because the output power of a single fuel cell is limited, high-power stacks are made by stacking dozens or even hundreds of identical fuel cells in series. Achieving high-performance and long-life fuel cell stacks remains a crucial goal for large-scale commercial applications. Improving the consistency of the mass, heat, electricity, and mechanical distribution within the fuel cell stack is essential to ensuring optimal performance and durability.

[0004] Ideally, the fuel cell stack needs to supply the same flow rate of reactant gas to each cell via a manifold. However, due to branching flow issues, achieving uniform fluid distribution within the stack is difficult in practice, especially for commercial stacks with a large number of cells and limited manifold space. Uneven cathode fluid distribution can affect the operating characteristics of individual cells, such as electrochemical reactions and ionic / electron conductivity. Cells with insufficient flow supply experience undergassing and flooding, leading to voltage drops and damage to the electrolyte membrane and catalyst. Conversely, cells with excessive flow supply can cause electrolyte membrane dehydration, reducing conductivity. Therefore, online measurement of cathode fluid distribution within the stack is crucial for improving stack performance and enhancing durability, providing strong support for highly consistent stack design and real-time stack health monitoring. However, a simple and effective method for detecting the consistency of fluid distribution in proton exchange membrane fuel cell stacks is currently lacking.

[0005] In existing technologies, the main methods for detecting the consistency of fluid distribution in a proton exchange membrane fuel cell stack include: 1) Embedded micro-sensors: Thermal or optical micro-flow sensors are embedded in the flow channels; pressure measuring rods are inserted into the main pipe of the stack to measure the pressure drop of each cell. Due to the millimeter-scale flow channel size, embedding sensors is difficult and may interfere with the operation of the stack. 2) Limiting current method: Hydrogen diluted with inert gas is introduced into the cathode side of the stack, and the limiting current of each cell is tested and compared. Since the consistency of the limiting current is affected by many factors, it cannot be determined whether it is caused by the consistency of fluid distribution, and it is not suitable for online monitoring. 3) Voltage decay method: Based on the fact that ohmic loss is mainly affected by the water content in the proton exchange membrane, the flow rate is determined by monitoring the voltage decay value of each cell. This method is only applicable to low-temperature proton exchange membrane fuel cells where the ohmic resistance is easily affected by the electrolyte water content. 4) Electrochemical impedance spectroscopy: Based on the relationship between flow channel impedance and cathode reactant flow rate, fixed-frequency impedance, flow channel impedance arc size, or physical model-correlated flow velocity are commonly used. These processing methods require parameter calibration in advance in an offline state or have high computational costs. Summary of the Invention

[0006] Electrochemical impedance spectroscopy is currently the most commonly used non-invasive, non-destructive monitoring technique; therefore, flow measurement methods based on this principle are easier to implement. To address the above issues, this invention provides a rapid, simple, in-situ, online method for detecting the consistency of cathode fluid distribution in a proton exchange membrane fuel cell stack.

[0007] This invention is mainly based on the electrochemical impedance measurement of each cell in the fuel cell stack. By constructing a simple correlation between the cathode reactive gas flow rate (or stoichiometry) and the characteristic frequency related to the oxygen mass transfer process, the cathode reactive gas flow rate of each cell in the fuel cell stack can be calculated.

[0008] This invention addresses the challenges of embedding methods, interference, offline measurement, limited applicability, and high computational costs. It proposes a rapid, simple, and in-situ online method for detecting the consistency of cathode fluid distribution in fuel cell stacks.

[0009] One aspect of this application provides a method for detecting cathode fluid distribution in a proton exchange membrane fuel cell stack, the method comprising: utilizing the characteristic frequency f of the flow channel impedance. ch The linear relationship with the cathode fluid stoichiometry 1 / ln(1-1 / λ) is used to determine the cathode gas volume flow rate Q(T,p) of each cell in the stack.

[0010] The detection principle of this invention is based on the correlation between the characteristic frequency of the flow channel impedance and the cathode reactive gas flow rate (or stoichiometry). For example... Figure 1 As shown, the local impedance in the low-frequency band is essentially a local sinusoidal oxygen concentration oscillation within the cathode catalyst layer. The local response. The sinusoidal oxygen concentration fluctuation comprises two processes. The oxygen fluctuation corresponding to process I occurs at the cathode electrode due to alternating current disturbance. Excited local oxygen concentration oscillation The oxygen fluctuations corresponding to process II are the oxygen concentration oscillations transmitted along the flow channel. It originates from upstream. Oxygen consumption along the flow path causes a decrease in oxygen concentration along the flow path, resulting in fluctuations in oxygen concentration at the cathode electrode. Extending into the flow channel. Furthermore, due to the forced air convection within the flow channel, these upstream oxygen concentration fluctuations ( Right now It is carried downstream along the flow channel and merges with the downstream... Coupling, in turn, affects the oxygen concentration within the downstream catalyst layer. Process II makes a significant contribution to the impedance response, thereby generating a second low-frequency arc, the so-called "channel impedance." Lower air stoichiometry implies lower air velocity, therefore, It is carried more slowly along the flow channel (corresponding to a smaller flow channel impedance characteristic frequency), which is why the characteristic frequency of the flow channel impedance can be correlated with the air stoichiometry.

[0011] To detect the consistency of fluid distribution in a proton exchange membrane fuel cell stack, this invention employs the following technical solution: While maintaining normal and stable operation of the stack, a multi-channel electrochemical workstation is used to test the electrochemical impedance spectroscopy (frequency range from 10 kHz to 0.1 Hz) of each individual cell in the stack. Characteristic frequencies of the flow channel impedance (the second low-frequency arc) related to oxygen transport in the flow channel are extracted through physical model fitting, equivalent circuit fitting (ECM), or relaxation time distribution (DRT) analysis. Based on the correlation between these characteristic frequencies and fluid flow rate or stoichiometry (e.g.,...), the... Figure 2 ), calculate the fluid flow rate or stoichiometry of each battery cell.

[0012] Optionally, the detection method specifically includes the following steps:

[0013] S001. Based on the electrochemical impedance spectroscopy of each cell, extract the characteristic frequency f of the oxygen transport process in the cathode channel of each cell. ch The effective depth h of the cathode flow channel of each cell is extracted by fitting the flow channel impedance arc of the electrochemical impedance model that takes into account the flow channel impedance and the measured electrochemical impedance.

[0014] S002. Calculate the average effective depth of the cathode flow channel of the fuel cell stack and the relative deviation of each section; if the obtained relative deviation is within 0 to 10%, calculate the air metering ratio λ of each cell according to Equation 1. n,cal ;

[0015]

[0016] Where h is any effective depth of the average cathode flow channel that is less than or equal to that of the fuel cell stack;

[0017] Among them, c ref The oxygen concentration at the inlet of each battery cell is denoted as F; F is the Faraday constant; and J is the current density during steady-state operation of the battery stack.

[0018] Numerical analysis revealed that if the relative deviation of h extracted from each cell in the fuel cell stack is less than 10%, using the average h value of all cells as the calculated value results in a smaller relative error (6.95%). Furthermore, using a value smaller than the average as the calculated value further reduces the relative error. Therefore, in this specific example, any value less than or equal to the average effective cathode channel depth of the entire stack can be used as the calculated value for h.

[0019] S003, Apply equation 2 to the λ obtained in step S002. n,cal Correction is performed to obtain an accurate stoichiometric ratio λ. n,cor ;

[0020]

[0021] Where N is the total number of cells in the stack, λ stack It is the stoichiometry of the air in the entire pile;

[0022] Optionally, if the overall value of h extracted by the model is too low, adjust the λ obtained in step S002 according to Equation 2. n,cal Perform corrections.

[0023] S004. Calculate the gas volume flow rate of each cathode section according to Equation 3.

[0024]

[0025] Where Q(T,p) is the gas volumetric flow rate (Lmin) of each cathode section. -1 A is the active surface area of ​​the battery (cm²). 2 ), where n is the number of electrons transferred, and λ is the accurate stoichiometric ratio of the cathode gas in each battery obtained in step S003. n,cor .

[0026] Optionally, the f described in step S001 ch Obtained through the following methods:

[0027] (1) During the stable operation of the proton exchange membrane fuel cell stack, the electrochemical impedance spectrum of each cell in the stack is collected;

[0028] (2) Analyze the electrochemical impedance spectroscopy obtained in step (1) to obtain f ch .

[0029] Optionally, in step (1), the electrochemical impedance spectra of each cell in the stack are collected by an electrochemical workstation, and the collection frequency range is , .

[0030] Optionally, in step (2), the analysis includes physical model fitting, equivalent circuit fitting, or relaxation time distribution analysis.

[0031] Optionally, in step S002, the c ref Calculate according to Equation 4

[0032]

[0033] Where p is the average pressure of the gas in the manifold, and T is the average temperature of the gas in the manifold. Let R be the molar ratio of oxygen, and R be the gas constant, which is 8.314 J / K. -1 mol -1 .

[0034] Oxygen concentration c at the inlet of each battery ref It depends on the humidity, temperature, and pressure within the manifold. Experimental results show that changes in humidity and temperature have little effect on the characteristic frequencies, such as... Figure 3 As shown. Furthermore, due to the short residence time of gas in the fuel cell stack manifold and the absence of a humidification source, the humidity change in the manifold itself is not significant. Additionally, the pressure difference within the commercial fuel cell stack manifold is small (approximately 1.3%). Therefore, the oxygen concentration at the manifold inlet can be taken as the oxygen concentration c at the inlet of each cell. ref .

[0035] Optionally, when dry air without humidification is introduced into the proton exchange membrane fuel cell stack, It is 0.21.

[0036] Optionally, the electrochemical impedance model and the measured electrochemical impedance spectroscopy data mentioned in step S001 are converted and fitted according to Equations 5 and 6, respectively.

[0037]

[0038]

[0039] Where Z is the complex impedance, Re(Z) is the real part of the complex impedance, and Im(Z) is the imaginary part of the complex impedance; R ∞ φ represents the membrane internal resistance; φ is the phase angle of the impedance data.

[0040] Where, tanφ exp Obtained from experimental data.

[0041] Optionally, Z expThis is the complex impedance obtained from testing; here, only the flow channel impedance arc data of the electrochemical impedance is selected for calculation. The real part of the impedance, Re(Z), is... exp Subtract the membrane resistance R ∞ This is to match the assumption of neglected ohmic resistance in the model, R ∞ Similarly, it can be extracted analytically through physical model fitting, equivalent circuit fitting (ECM), or relaxation time distribution (DRT).

[0042] Optionally, the Z exp Obtained by measuring electrochemical impedance spectroscopy;

[0043] The R ∞ The following method was used to obtain the electrochemical impedance spectroscopy (EIS) of each cell in the proton exchange membrane fuel cell stack during stable operation: The obtained EIS was analyzed to obtain R0. ∞ The analysis mentioned therein includes any one of physical model fitting, equivalent circuit fitting (ECM), or relaxation time distribution analysis (DRT);

[0044] Optionally, the electrochemical impedance spectroscopy of each cell in the stack is collected using an electrochemical workstation, with a collection frequency range of 0.1 Hz to 10 kHz.

[0045] This application introduces an electrochemical impedance model, as shown in Equation 7. The effective depth h of the cathode flow channel of each battery is extracted by fitting Equation 7. In actual testing, it is not limited to the electrochemical impedance model mentioned in this application.

[0046]

[0047] in,

[0048] m=4Fhc ref (Equation 8)

[0049] n=λqJ (Equation 9)

[0050]

[0051] Im(D)=-mβω-nδm 2 ω 3 +mnγωcosα+(n 2 -mδω 2 )γsinα (Equation 11)

[0052]

[0053] β=γn-Jm 2 ω 2 (Equation 13)

[0054] γ=(λ-1)Jn (Equation 14)

[0055]

[0056]

[0057]

[0058] The phase angle of the impedance data is given by ω, the angular frequency is given by F, and the F is the Faraday constant, which is 96485 C mol. -1 c ref Oxygen concentration at the inlet of each battery cell (mol / cm³) -3 );f ct Characteristic frequencies associated with the oxygen reduction reaction process, f ch Let J be the characteristic frequency (Hz) of the flow channel impedance of each battery cell, and J be the current density (A cm⁻¹) during steady-state operation of the battery stack. -2 ), where λ is the stoichiometric ratio of the cathode gas in each battery cell;

[0059] Due to factors such as the embedding of the gas diffusion layer into the flow channel after assembly, the effective depth h (cm) of the cathode flow channel in each battery cell will be less than the measured value before assembly. Therefore, the effective depth h needs to be extracted by fitting the electrochemical impedance model according to Equation 1.

[0060] According to equations 7 to 17, we can obtain tan Regarding ω, λ, h, J, f ct Functions with equal parameters. To improve accuracy, all parameters except h were calculated from experimental data.

[0061] Where ω is the impedance data obtained from the test (ω=2πf), and J is the current density of the fuel cell during the test.

[0062] Optionally, the f ct Obtained through the following methods:

[0063] (1) During the stable operation of the proton exchange membrane fuel cell stack, the electrochemical impedance spectrum of each cell in the stack is collected;

[0064] (2) Analyze the electrochemical impedance spectroscopy obtained in step (1) to obtain f ct 、.

[0065] Optionally, the detection method is applicable when the relative deviation of the effective depth of the cathode flow channel of each battery cell is within 0 to 10%.

[0066] Since this method is based on the relationship between channel impedance characteristics and gas flow rate, its application presupposes that the channel impedance of each cell in the fuel cell stack can be measured. According to the above testing principle, the main cause of channel impedance is the consumption of oxygen concentration in the channel. Therefore, the applicability of this method depends on the channel geometry and the fuel cell stack operating conditions (gas flow rate, current density, gas oxygen concentration, etc.).

[0067] The beneficial effects that this application can produce include:

[0068] Compared with existing technologies, the fuel cell stack fluid distribution consistency detection method described in this application is simple, easy to implement, practical and effective. All parameters are extracted only from the real-time measured electrochemical impedance spectroscopy, without the need for prior calibration, which is of great significance for high-consistency stack design and health status monitoring of individual cells in the stack. Attached Figure Description

[0069] Figure 1 This is a schematic diagram illustrating the principle of flow channel impedance generation.

[0070] Figure 2 This is a graph showing the relationship between the characteristic frequency of the flow channel impedance and the air stoichiometry, which is related to the oxygen transport process in the flow channel.

[0071] Figure 3 The figure shows the effect of operating conditions on the relaxation time distribution, where the operating condition changed in figure a is humidity, and the operating condition changed in figure b is temperature.

[0072] Figure 4 A schematic diagram of the model fitting for extracting the effective flow channel depth, using experimental data tanφ. exp With model tanφ c The comparison.

[0073] Appendix Figure 5 In the example, Case 1 extracts the effective flow channel depth of each cell under different stoichiometric ratios and the maximum relative deviation of the depth among the three cells.

[0074] Appendix Figure 6 The fluid distribution test results of Example 1.

[0075] Wherein, 1 is the cathode flow channel, 2 is the gas diffusion layer, and 3 is the cathode catalyst layer. Detailed Implementation

[0076] Example 1

[0077] To verify the accuracy of the method in this embodiment, the fuel cell stack used is a specially designed stack consisting of three high-temperature proton exchange membrane fuel cells stacked in series with independent gas paths. Each cell's gas supply is equipped with a mass flow meter to facilitate the provision of reference values ​​for measurements. Non-humidifying gas is introduced into the anode or cathode inlet of the fuel cell stack, and voltage acquisition points are set at the anode and cathode of each cell, using Solartron... An electrochemical workstation (including a 1470E potentiostat and a 1455 frequency response analyzer) recorded electrochemical impedance spectroscopy (EIS) in constant current mode. The EIS of each cell in the stack was simultaneously recorded via the workstation's auxiliary voltage divider channel, and the inlet air metering ratio of each cell was calculated to determine the consistency of fluid distribution within the fuel cell stack. All test stacks were operated at 160℃ and a current density of 100 mA / cm². -2 Under steady-state operation. Since each gas path is independent, three different gas distribution scenarios were simulated (Scenario 1 corresponds to uniform distribution among all battery cells; Scenario 2 corresponds to a relative standard deviation of 5%; Scenario 3 corresponds to a relative standard deviation of 10%), and different total flow rates were also simulated for each distribution scenario.

[0078] A method for detecting the consistency of fluid distribution in a fuel cell stack includes the following steps:

[0079] 1) During the stable operation of the fuel cell stack, the electrochemical impedance spectra of each cell in the stack are collected using an electrochemical workstation, with a collection frequency range of 10kHz to 0.1Hz;

[0080] 2) The membrane resistance R is extracted from the electrochemical impedance spectroscopy obtained by relaxation time distribution (DRT) analysis. ∞ Characteristic frequencies f associated with the oxygen reduction reaction process ct and characteristic frequencies f associated with oxygen mass transfer processes ch And read the current density J, and calculate the oxygen concentration c. ref ;

[0081] 3) Combining the parameters obtained in step 2) with the experimentally measured flow channel impedance data, the effective flow channel depth h of each battery cell is obtained by fitting the model described above. Some fitting results are shown below. Figure 4 As shown, the average effective depth of the cathode flow channel and the relative deviation of each section of the fuel cell stack are calculated.

[0082] 4) Determine if the calculated relative deviation is less than 10%. If so, use the average effective depth of the cathode flow channel of the fuel cell stack and the characteristic frequency f of each cell related to the oxygen mass transfer process. ch Substitute into formula (18) to calculate the air metering ratio λ of each battery. n,cal Otherwise, this method has a large error and is not applicable; such as Figure 5As shown, the relative deviation of the extracted effective flow channel depth is within 0 to 10%.

[0083]

[0084] 5) The accurate stoichiometric ratio can be obtained by correction according to formula (19), and further, it can be converted into volumetric flow rate according to formula (20).

[0085]

[0086]

[0087] Comparison of test results with air volume calculated by mass flow meter, for example Figure 6 As shown in the figure, compared with the reference value calculated by the mass flow meter, the relative error of all test results in this embodiment is less than 3.11%, indicating good accuracy.

[0088] Example 2

[0089] Follow these steps to create an active area of ​​45 cm². 2 A high-temperature proton exchange membrane fuel cell with a serpentine flow channel operates at 160°C and 200 mA cm⁻¹. -2 The experiment was conducted under different cathode-air stoichiometry ratios to measure electrochemical impedance spectroscopy; then, the impedance spectra were analyzed to extract f. ch .get Figure 2 ,Depend on Figure 2 It can be seen that there is a linear relationship between the characteristic frequency of the flow channel impedance related to the oxygen transport process in the flow channel and the air stoichiometry.

[0090] Example 3: The effect of operating conditions on relaxation time distribution.

[0091] The test should be conducted according to the following steps: An active area of ​​45 cm² 2 A high-temperature proton exchange membrane fuel cell with a serpentine flow channel operates at 160°C and 200 mA cm⁻¹. -2 The electrochemical impedance spectroscopy (EIS) was tested under varying humidity conditions at the battery cathode; then, the EIS was analyzed to extract fo. ch ,get Figure 3 a,

[0092] An active area of ​​45cm² 2 A high-temperature proton exchange membrane fuel cell with a serpentine flow channel was operated at 200 mA cm⁻². The operating temperature was varied, and electrochemical impedance spectroscopy (EIS) was measured. The EIS was then analyzed to extract fo. ch .get Figure 3 b

[0093] Test results are available Figure 3 In Figure a, the operating condition is changed by humidity; in Figure b, the operating condition is changed by temperature. Peak P1 is related to the oxygen transport process in the flow channel, and peak P2A is related to the oxygen reduction reaction process. The frequencies corresponding to the peak apexes are the characteristic frequencies of the corresponding processes. Figure 3 As can be seen from this, temperature and humidity affect the characteristic frequency f of the flow channel impedance. ch The impact is small.

[0094] Example 4 Experimental Data tan With model tan Comparison

[0095] This data comes from an active area of ​​160 cm². 2 A three-cell high-temperature proton exchange membrane fuel cell stack with parallel flow channels was tested at 160°C and 100 mA cm⁻¹. -2 The results were obtained from the following test. (Test results input) Figure 4 Among them, the solid annotation lines represent the tan... Predicted values; hollow lines represent experimental data (tan).

[0096] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for detecting cathode fluid distribution in a proton exchange membrane fuel cell stack, characterized in that, The detection method includes: utilizing the characteristic frequency of the flow channel impedance. Stoichiometry with cathode fluid The linear relationship is used to determine the cathode gas volume flow rate of each cell in the stack. ; The detection method includes the following steps: S001. Based on the electrochemical impedance spectroscopy of each cell, extract the characteristic frequencies of the oxygen transport process in the cathode channel of each cell. The effective depth h of the cathode flow channel of each cell is extracted by fitting the flow channel impedance arc of the electrochemical impedance model that takes into account the flow channel impedance and the measured electrochemical impedance. S002. Calculate the average effective depth of the cathode flow channel of the fuel cell stack and the relative deviation of each section; if the obtained relative deviation is within 0~10%, calculate the air metering ratio of each cell according to Equation 1. ; (Equation 1) Where h is any effective depth of the average cathode flow channel that is less than or equal to that of the fuel cell stack; in, The oxygen concentration at the inlet of each battery cell; It is Faraday's constant; This represents the current density during steady-state operation of the fuel cell stack. S003, Apply the solution obtained in step S002 according to formula 2. Perform calibration to obtain an accurate stoichiometric ratio. ; (Equation 2) in, It is the total number of cells in the fuel cell stack. It is the stoichiometry of the air in the entire pile; S004. Calculate the gas volume flow rate of each cathode section according to Equation 3. (Equation 3) in The volumetric gas flow rate of each cathode section. This represents the active surface area of ​​the battery. For electron transfer number, The accurate stoichiometry of the cathode gas of each battery obtained in step S003 .

2. The detection method according to claim 1, characterized in that, The steps described in step S001 Obtained through the following methods: (1) During the stable operation of the proton exchange membrane fuel cell stack, the electrochemical impedance spectra of each cell in the stack are collected; (2) Analyze the electrochemical impedance spectroscopy obtained in step (1) to obtain... .

3. The detection method according to claim 2, characterized in that, In step (1), the electrochemical impedance spectra of each cell in the stack are collected by an electrochemical workstation, with a collection frequency range of 0.1 Hz to 10 kHz.

4. The detection method according to claim 2, characterized in that, In step (2), the analysis is selected from at least one of physical model fitting, equivalent circuit fitting, or relaxation time distribution analysis.

5. The detection method according to claim 1, characterized in that, In step S002, the Calculate according to Equation 4 (Equation 4) in, The average pressure of the gas inside the manifold. The average temperature of the gas inside the manifold. R is the molar ratio of oxygen, and R is the gas constant.

6. The detection method according to claim 5, characterized in that, When dry air without humidification is introduced into the proton exchange membrane fuel cell stack It is 0.

21.

7. The detection method according to claim 1, characterized in that, The electrochemical impedance model and the measured electrochemical impedance spectroscopy data mentioned in step S001 are converted and fitted according to Equations 5 and 6, respectively. (Equation 5); (Equation 6) in, For complex impedance, Let be the real part of the complex impedance. This represents the imaginary part of the complex impedance; For membrane resistance; This represents the phase angle of the impedance data.

8. The detection method according to claim 7, characterized in that, The Obtained by measuring electrochemical impedance spectroscopy; The The electrochemical impedance spectroscopy (EIS) of each cell in the proton exchange membrane fuel cell stack was obtained through the following method: during the stable operation of the stack, the EIS was collected; the obtained EIS was then analyzed to obtain... The analysis is selected from at least one of physical model fitting, equivalent circuit fitting, or relaxation time distribution analysis. The electrochemical impedance spectra of each cell in the fuel cell stack were collected using an electrochemical workstation, with a sampling frequency range of 0.1 Hz to 10 kHz.

9. The detection method according to claim 1, characterized in that, The detection method is applicable when the relative deviation of the effective depth of the cathode flow channel of each battery is within 0 to 10%.

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