A calculation method for the current density distribution of a large-area fuel cell

Abstract

The present invention relates to a method for calculating the current density distribution of a large-area fuel cell, comprising the following steps: S1, obtaining voltage data at the anode outlet and the anode inlet of the fuel cell; S2, obtaining the flow rate, pressure and relative humidity at the anode inlet of the fuel cell and the flow rate, pressure and relative humidity data at the cathode inlet; S3, obtaining temperature sampling data inside the bipolar plate of the fuel cell; S4, constructing a four-chamber gas dynamic model and a voltage model; S5, importing the obtained data based on the four-chamber gas dynamic model and the voltage model and then calculating the current density distribution. Compared with the prior art, the present invention has the advantages of not requiring the arrangement of complex sensors, convenient calculation, high accuracy, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of state monitoring of large-area fuel cells for transportation power systems, and particularly to a method for calculating the current density distribution of a large-area fuel cell. Background Art

[0002] Due to the characteristics of pollution-free emissions, fuel cells have received increasing attention worldwide. A fuel cell is essentially an electrochemical device that uses hydrogen and oxygen as fuels and generates electrical energy through an electrochemical reaction (non-combustion). The commercialization of fuel cells still faces many problems, including high costs, low lifetimes, and poor durability. As fuel cells tend to have a larger active area, the uneven distribution of each component inside the fuel cell leads to a further expansion of the in-plane difference of the fuel cell. Moreover, as the number of fuel cell sheets increases, the consistency of the fuel cell system will also be affected, ultimately resulting in a reduction in the durability and lifetime of the fuel cell.

[0003] With the continuous increase in the power demand of fuel cells, more and more manufacturers choose fuel cell monomers with a large active area to form a fuel cell stack. Compared with the fuel cells with an active area of 25 cm 2 mostly used in existing research, in the direction of the gas flow channel of a large-area fuel cell, obvious concentration attenuation will occur. On the one hand, it is due to the difference in in-plane gas flow distribution, and on the other hand, it is because the hydrogen-oxygen reaction continuously consumes the reaction gases, further expanding the concentration difference of the reaction gases in the large-area fuel cell in-plane. In addition, different from the small-area fuel cell single sheet used in laboratory tests, a large-area fuel cell single sheet also means an increase in the heat generation power and the external contact area, and the requirements and difficulties of temperature control will also increase significantly. Therefore, generally, there are also differences in the temperature distribution in-plane of a proton exchange membrane fuel cell for vehicles. When the current density is 2000 mA / cm2, the coolant outlet temperature of the fuel cell is nearly 4 °C higher than the coolant inlet temperature, while at a low current density, the in-plane temperature difference of the fuel cell is within 0.5 °C. The fuel cell is highly sensitive to temperature, and the temperature difference at a high current density will significantly affect the reaction rate in the fuel cell in-plane. Therefore, a method for calculating the current density distribution of a large-area fuel cell is needed to objectively reflect the change process of the current in the dynamic process in real time. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for calculating the current density distribution of a large-area fuel cell to overcome the defects existing in the above-mentioned prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A method for calculating the current density distribution of a large-area fuel cell, the method comprising the following steps:

[0007] S1. Obtain the voltage data at the anode outlet and anode inlet of the fuel cell;

[0008] S2. Obtain the flow rate, pressure, and relative humidity at the anode inlet of the fuel cell and the flow rate, pressure, and relative humidity data at the cathode inlet;

[0009] S3. Obtain the temperature sampling data inside the bipolar plate of the fuel cell;

[0010] S4. Construct a four-chamber gas dynamic model and a voltage model;

[0011] S5. Based on the four-chamber gas dynamic model and the voltage model, import the obtained data and calculate the current density distribution.

[0012] In the step S1, the voltage data is obtained by the voltage inspection instrument arranged at the anode outlet and anode inlet of the fuel cell.

[0013] In the step S2, the flow rate, pressure, and relative humidity at the anode inlet of the fuel cell and the flow rate, pressure, and relative humidity data at the cathode inlet are obtained by the fuel cell test bench.

[0014] In the step S3, the temperature sampling data inside the bipolar plate of the fuel cell is obtained by an external data acquisition card.

[0015] In the step S4, the four-chamber gas dynamic model specifically describes the gas dynamics process at the inlet and outlet in the cathode / anode channels according to the mass conservation principle of oxygen, nitrogen, hydrogen, and water vapor, and all substances are regarded as ideal gases.

[0016] The fuel cell adopts a cathode-anode cross-gas supply mode. During the construction of the four-chamber gas dynamic model, the fuel cell is divided into two half-cells, and there are:

[0017] 1) The cathode inlet cavity chamber 1 and the anode outlet cavity chamber 4 together form a half-cell, namely the anode outlet half-cell;

[0018] 2) The cathode outlet cavity chamber 2 and the anode inlet cavity chamber 3 together form another half-cell, namely the anode inlet half-cell;

[0019] 3) The two half-cells work in parallel, and the reaction gas flow is in a series relationship;

[0020] 4) The cathode fresh air first enters the anode outlet half-cell, reacts in the anode outlet half-cell, then enters the anode inlet half-cell, and then is discharged from the fuel cell;

[0021] 5) The anode fresh hydrogen first enters the anode inlet half-cell, reacts in the anode inlet half-cell, then enters the anode outlet half-cell, and then is discharged from the fuel cell;

[0022] 6) Changes in the anode gas concentration or the cathode gas concentration will both result in the redistribution of the current and voltage inside the fuel cell.

[0023] For the cathode inlet plenum chamber 1, its state equation is:

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] Among them, is the partial pressure of nitrogen in chamber 1, is the partial pressure of oxygen in chamber 1, V ca is the volume inside the chamber, i1 is the current in the anode outlet half-cell, A is the effective active area, F is the Faraday constant, N is the number of cell sheets, R is the gas constant, is the molar flow rate of the inlet air, is the air oxygen mole fraction of the cathode inlet flow rate, which is calculated based on the relative humidity of 60% at the cathode inlet, is the air oxygen mole fraction in chamber 1, is the molar flow rate between chamber 1 and chamber 2, is the oxygen concentration in chamber 1, T fc is the operating temperature of the fuel cell, t is the time, P ch1 is the gas pressure inside chamber 1, is the local saturation vapor pressure;

[0030] For the cathode outlet chamber chamber 2, its state equation is:

[0031]

[0032]

[0033]

[0034]

[0035]

[0036] Among them, is the partial pressure of nitrogen in chamber 2, is the partial pressure of oxygen in chamber 2, is the molar fraction of oxygen in the air at the cathode outlet, is the oxygen concentration in chamber 2, is the molar flow rate of the outlet air, P ch2 is the gas pressure in chamber 2, is the partial pressure of water vapor in the cathode flow channel, is the molar fraction of oxygen in the air in chamber 2.

[0037] For the anode inlet chamber, chamber 3, its state equation is:

[0038]

[0039]

[0040]

[0041] Wherein, is the molar flow rate of the inlet hydrogen, is the molar fraction of hydrogen in the anode inlet flow, which is calculated based on the relative humidity at the anode inlet of 40%, is the local saturation vapor pressure, is the hydrogen pressure in chamber 3, V an is the volume in the anode flow channel, is the molar flow rate between chamber 3 and chamber 4, is the molar fraction of oxygen in the air in chamber 3, P ch3 is the gas pressure in chamber 3;

[0042] For the anode outlet chamber, chamber 4, its state equation:

[0043]

[0044]

[0045]

[0046] Wherein, is the hydrogen pressure in chamber 4, is the hydrogen flow rate to be excluded, P ch4 is the gas pressure in chamber 4, is the molar fraction of oxygen in the air in chamber 4.

[0047] In the said step S4, the voltage model is specifically:

[0048]

[0049] Wherein, V fc is the actual voltage of the fuel cell, is the Nernst potential, vact is the activation overpotential, V ohm is the ohmic overpotential, V conc is the concentration overpotential

[0050] The Nernst potential mentioned above is calculated by the Nernst equation, and there is:

[0051]

[0052] wherein is the partial pressure of hydrogen at the anode is the partial pressure of oxygen at the cathode, k E , k C are respectively empirical parameters obtained through parameter identification

[0053] The activation overpotential V mentioned above act is calculated by the Tafel semi-empirical formula and Henry's law, and there is:

[0054]

[0055] wherein is the dissolved oxygen concentration at the three-phase reaction interface of the cathode catalyst layer, and I is the actual current of the fuel cell

[0056] The ohmic overpotential V mentioned above ohm is the voltage drop caused by the equivalent impedance R m of protons passing through the exchange membrane, and there is:

[0057] V ohm (R m , I) = I × R m

[0058]

[0059] wherein L m is the thickness of the proton exchange membrane, A is the effective active area, λ m is the membrane water content, and α is an empirical parameter obtained through parameter identification

[0060] The concentration overpotential V mentioned above conc is calculated by the formula:

[0061] V conc (i) = βe i

[0062] wherein β and i are respectively empirical parameters obtained through parameter identification, and e is the natural logarithm

[0063] Compared with the prior art, the present invention has the following advantages:

[0064] 1. The present invention does not require a complex sensor system, such as a PCB board, to be arranged inside the battery to obtain the current distribution.

[0065] 2. The present invention only needs to obtain conventional battery parameters to conveniently calculate the current distribution.

[0066] 3. The present invention comprehensively considers the cathode and anode to construct a four-chamber gas dynamic model, which can cover the reaction characteristics of the anode, cathode, and exchange membrane, and has better accuracy compared with other methods.

[0067] 4. The four-chamber gas dynamic model constructed by the present invention can reflect the change processes of current and voltage in the dynamic process. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 is a flowchart of the method of the present invention.

[0069] Figure 2 is a schematic diagram of multi-point voltage sampling of the present invention.

[0070] Figure 3 is a half-cell hypothesis of the present invention.

[0071] Figure 4 is a schematic diagram of the temperature sampling arrangement of the present invention.

[0072] Figure 5 is a schematic diagram of the temperature distribution of the present invention.

[0073] Figure 6 is a schematic diagram of the comparison of the model accuracy of the present invention.

[0074] Figure 7 is the prediction result of the model of the present invention. Among them, Fig. (7a) is a schematic diagram of the current and voltage distribution under the condition of 210A, and Fig. (7b) is a schematic diagram of the current and voltage distribution under the condition of 450A. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0075] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0076] Embodiment

[0077] As Figure 1As shown in the figure, the present invention provides a method for calculating the current density distribution of a large-area fuel cell. The present invention is applicable to large-area graphite plate fuel cells. By arranging voltage sampling points at the anode inlet and the anode outlet respectively, the voltages at the anode inlet and the anode outlet of the fuel cell are obtained; and temperature sensors are arranged in the bipolar plates of the battery to obtain the temperature distribution in the battery. In view of the in-plane non-uniformity of a large-area fuel cell monomer, based on multi-point voltage data and multi-point temperature data, a four-chamber gas dynamic model and a voltage model of the fuel cell are established to obtain the current density distributions at the anode inlet and the anode outlet of the fuel cell respectively. The method specifically includes the following steps:

[0078] S1. Obtain the voltages at the anode outlet and the anode inlet of the large-area fuel cell;

[0079] The voltages at the anode inlet and the anode outlet of the fuel cell are obtained by a voltage inspection instrument. Input the voltage information at the anode inlet and the anode outlet of the fuel cell, and use this voltage data as the main parameter for estimating the current density.

[0080] In this example, taking a large-area graphite plate fuel cell as an example, under various test conditions, the voltage information at two positions is obtained, and when the current density rises from 100 mA / cm 2 to 2000 mA / cm 2 , the voltages at the two positions show relatively obvious differences.

[0081] S2. Obtain the anode inlet flow rate, pressure and relative humidity of the fuel cell, as well as the cathode inlet flow rate, pressure and relative humidity;

[0082] Since the fuel cell test bench has functions such as gas flow control, gas pressure control and gas humidity control, in this example, the fuel cell test bench is used to directly obtain these parameters.

[0083] S3. Obtain the temperature sampling data arranged inside the bipolar plate;

[0084] Among them, the temperature sensor arrangement scheme in this example is as Figure 4 shown. Under different current densities, the in-plane temperature distribution of the battery will show large differences. As Figure 5 shown, at a current density of 100 mA / cm 2 , the temperature distribution difference inside the battery is 0.3 °C. When the current density rises to 2000 mA / cm 2 , the temperature distribution difference inside the battery is 4.5 °C.

[0085] S4. Build a four-chamber gas dynamic model and a voltage model;

[0086] The four-chamber gas dynamic model describes the gas dynamics process at the inlet and outlet in the cathode / anode channels by applying the mass conservation principles of oxygen, nitrogen, hydrogen, and water vapor. All substances are regarded as ideal gases. Among them, the fuel cell adopts a cathode-anode cross-gas supply mode. During the model construction, the fuel cell is divided into two half-cells (as shown in Figure 3 ):

[0087] 1) The cathode inlet chamber cavity 1 and the anode outlet chamber cavity 4 together form a half-cell, namely the anode outlet half-cell;

[0088] 2) The cathode outlet chamber cavity 2 and the anode inlet chamber cavity 3 together form another half-cell, namely the anode inlet half-cell;

[0089] 3) The two fuel cell half-cells work in parallel, but the reaction gas flow is in a series relationship;

[0090] 4) The cathode fresh air first enters the anode outlet half-cell, reacts in the anode outlet half-cell and then enters the anode inlet half-cell, and then is discharged from the fuel cell;

[0091] 5) The anode fresh hydrogen first enters the anode inlet half-cell, reacts in the anode inlet half-cell and then enters the anode outlet half-cell, and then is discharged from the fuel cell;

[0092] 6) Whether it is the change in the anode gas concentration or the change in the cathode gas concentration, it will cause the redistribution of the current and voltage inside the fuel cell.

[0093] For the cathode inlet chamber cavity 1, the following state equation is obtained:

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] Equations (1)-(5) are the mass conservation equations of oxygen and nitrogen. In addition, the present invention uses a filling and emptying model to calculate the chamber pressure. During this process, nitrogen cannot be consumed, but the oxygen consumption rates of the two chambers are different, and the oxygen consumption changes the oxygen pressure and affects the sampling voltage.

[0100] In the formula, represents the partial pressure of nitrogen in cavity 1, represents the partial pressure of oxygen in cavity 1, V carepresents the volume inside the cavity 1, i1 represents the current in the anode outlet half-cell, A represents the active area of the half-cell at the anode outlet, F represents the Faraday constant, N represents the number of battery cells, R represents the gas constant, represents the molar flow rate of the inlet air, taken from the mass flow sensor on the test bench, and the molar fraction of oxygen in the air at the cathode inlet flow rate Calculated based on a relative humidity of 60% at the cathode inlet, the molar fraction of oxygen in the air in the cathode inlet cavity 1 is the molar flow rate between the cathode inlet cavity 1 and the cathode outlet cavity 2, is the oxygen concentration in the cathode inlet cavity 1. Due to the assumption of complete humidification, the vapor pressure is equal to the local saturation vapor pressure It is determined by the fuel cell operating temperature T fc and then there is:

[0101]

[0102] For the cathode outlet cavity 2, the following state equation is obtained:

[0103]

[0104]

[0105]

[0106]

[0107]

[0108] In the formula, represents the partial pressure of nitrogen in the cavity 2, represents the partial pressure of oxygen in the cavity 2, represents the molar fraction of oxygen in the air at the cathode outlet flow rate, is the oxygen concentration in the cathode outlet cavity 2.

[0109] In this example, and Calculated according to Darcy's law, then there is:

[0110]

[0111]

[0112] Similarly, for the anode inlet cavity 3, the following state equation is obtained:

[0113]

[0114]

[0115]

[0116] In the formula, represents the molar flow rate of the inlet hydrogen, taken from the mass flow sensor of the test bench, and the molar fraction of hydrogen in the anode inlet flow is calculated based on the relative humidity of 40% at the anode inlet. Similarly, due to the fully humidified assumption, the vapor partial pressure is equal to the local saturated vapor pressure It is determined by the fuel cell operating temperature T fc as follows:

[0117] For the anode outlet cavity 4, the following state equation is obtained:

[0118]

[0119]

[0120]

[0121] Similarly, comparing with the anode flow channel, the in the equation represents the molar flow rate between the anode inlet cavity 3 and the anode inlet cavity 4. In this example, and are calculated according to Darcy's law:

[0122]

[0123]

[0124] In the present invention, the cathode inlet cavity 1 and the anode outlet cavity 4 together form a half-cell, and the cathode outlet cavity 2 and the anode inlet cavity 3 together form another half-cell. Therefore, whether it is the change in the anode gas concentration or the change in the cathode gas concentration, it will cause the redistribution of the current and voltage inside the fuel cell.

[0125] S5. Import the monitored data into the model and calculate the current distribution;

[0126] For this purpose, it is necessary to establish the relationship between the internal pressure, flow rate, temperature of the fuel cell and the measured parameters such as current and voltage. According to the terminal voltage model, the relationship between the oxygen partial pressure, hydrogen partial pressure, cell temperature, oxygen concentration, current and voltage is revealed:

[0127]

[0128] Among them, V fc is the actual voltage of the fuel cell, is the Nernst potential, and v act is the activation overpotential, vohm is the ohmic overpotential, v conc is the concentration overpotential.

[0129] In the ideal case, without considering losses, the Nernst potential can be calculated using the Nernst equation:

[0130]

[0131] where is the partial pressure of hydrogen at the anode, is the partial pressure of oxygen at the cathode, T fc is the battery temperature.

[0132] The activation overpotential refers to the resistance that needs to be overcome to activate a chemical reaction at the beginning of the chemical reaction. Although activation overpotentials occur at both the cathode and the anode, the reduction reaction rate on the cathode side is much smaller than the hydrogen oxidation rate. Therefore, generally, the cathode determines the activation overpotential. Accordingly, the activation overpotential can be calculated from the Tafel semi-empirical formula and Henry's law:

[0133]

[0134] where k E is an empirical parameter whose value is identified from experimental data, is the dissolved oxygen concentration at the three-phase reaction interface of the cathode catalyst layer, and I is the actual current of the fuel cell.

[0135] The ohmic overpotential is the voltage drop caused by the equivalent impedance R m of the proton passing through the exchange membrane. According to Ohm's law, it can be calculated by the following formula:

[0136] v ohm (R m ,I) = I × R m (25)

[0137]

[0138] where L m is the thickness of the proton exchange membrane, A is the effective active area of the battery, λ m is the membrane water content.

[0139] At high current densities, the mass transfer of reactants or products is hindered, resulting in a concentration overpotential. The concentration voltage loss can be calculated as:

[0140] v conc (I) = βe I (27)

[0141]

[0142]

[0143] Δi = i1 - i2

[0144] The present invention uses a voltage model based on oxygen partial pressure, hydrogen partial pressure, battery temperature, and oxygen concentration to analyze the current distribution difference. Δi is the current difference between two half-cells, and the double-sampled voltage of each unit is the boundary condition of 27 equations. is the dissolved oxygen concentration at the three-phase reaction interface of the cathode catalyst layer in chamber 1, and i1 is the current in half-cell 1; is the dissolved oxygen concentration at the three-phase reaction interface of the cathode catalyst layer in chamber 2, and i2 is the current in half-cell 2; V fc1 is the voltage measured in half-cell 1; V fc2 is the voltage measured in half-cell 2.

[0145] The above shows and describes the basic principles, main features, and advantages of the present invention. Obviously, those skilled in the art should understand that the above embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. Those skilled in the art can make other changes within the main idea of the present invention, and these obvious changes derived therefrom should all be included within the scope claimed by the present invention.

Claims

1. A method for calculating the current density distribution of a large-area fuel cell, characterized in that The method includes the following steps: S1. Obtain the voltage data at the anode outlet and anode inlet of the fuel cell; S2. Obtain the flow rate, pressure, and relative humidity at the anode inlet of the fuel cell and the flow rate, pressure, and relative humidity data at the cathode inlet; S3. Obtain the temperature sampling data inside the bipolar plate of the fuel cell; S4. Construct a four-chamber gas dynamic model and a voltage model; The fuel cell adopts a cathode-anode cross-gas supply mode. During the construction of the four-chamber gas dynamic model, the fuel cell is divided into two half-cells, and there are: 1) The cathode inlet chamber cavity 1 and the anode outlet chamber cavity 4 together form a half-cell, namely the anode outlet half-cell; 2) The cathode outlet chamber cavity 2 and the anode inlet chamber cavity 3 together form another half-cell, namely the anode inlet half-cell; 3) The two half-cells work in parallel, and the reaction gas flow is in a series relationship; For the cathode inlet chamber cavity 1, its state equation is: Among them, is the partial pressure of nitrogen in chamber 1, is the partial pressure of oxygen in chamber 1, is the volume inside the chamber, is the current in the anode outlet half-cell, is the effective active area, is the Faraday constant, is the number of battery cells, is the gas constant, is the molar flow rate of the inlet air, is the air oxygen mole fraction of the cathode inlet flow rate, which is calculated based on the relative humidity of 60% at the cathode inlet, is the air oxygen mole fraction in chamber 1, is the molar flow rate between chamber 1 and chamber 2, is the oxygen concentration in chamber 1, is the operating temperature of the fuel cell, is the time, is the gas pressure in chamber 1, is the local saturation vapor pressure; For the cathode outlet chamber cavity 2, its state equation is: wherein, is the partial pressure of nitrogen in chamber 2, is the partial pressure of oxygen in chamber 2, is the current in the anode inlet half-cell, is the air oxygen mole fraction of the cathode outlet flow rate, is the oxygen concentration in chamber 2, is the molar flow rate of the outlet air, is the gas pressure in chamber 2, is the partial pressure of water vapor in the cathode flow channel, is the air oxygen mole fraction in chamber 2; For the anode inlet chamber cavity 3, its state equation is: Among them, is the molar flow rate of the inlet hydrogen, is the hydrogen molar fraction of the anode inlet flow rate, which is calculated based on the relative humidity of 40% at the anode inlet, is the local saturation vapor pressure, is the hydrogen pressure in chamber 3, is the volume in the anode flow channel, is the molar flow rate between chamber 3 and chamber 4, is the air-hydrogen molar fraction in chamber 3, is the gas pressure in chamber 3; For the anode outlet chamber cavity 4, its state equation: Among them, is the hydrogen pressure in the cavity 4, is the hydrogen flow rate discharged, is the gas pressure in the cavity 4, is the air-hydrogen molar fraction in the cavity 4, is the hydrogen molar fraction of the anode outlet flow rate; In step S4, the voltage model is specifically: Among them, is the actual voltage of the fuel cell, is the Nernst potential, is the activation overpotential, is the ohmic overpotential, is the concentration overpotential; S5. Based on the four-chamber gas dynamic model and the voltage model, import the obtained data and calculate the current density distribution.

2. The method for calculating the current density distribution of a large-area fuel cell according to claim 1, characterized in that, In step S1, the voltage data is obtained by a voltage inspection instrument arranged at the anode outlet and anode inlet of the fuel cell.

3. A method for calculating the current density distribution of a large-area fuel cell according to claim 1, characterized in that, In step S2, the flow rate, pressure, and relative humidity at the anode inlet of the fuel cell and the flow rate, pressure, and relative humidity data at the cathode inlet are obtained through a fuel cell test bench.

4. A method for calculating the current density distribution of a large-area fuel cell according to claim 1, characterized in that, In step S3, the temperature sampling data inside the bipolar plate of the fuel cell is obtained through an external data acquisition card.

5. A method for calculating the current density distribution of a large-area fuel cell according to claim 1, characterized in that, In step S4, the four-chamber gas dynamic model specifically describes the gas dynamics process at the inlet and outlet in the cathode / anode channels according to the mass conservation principle of oxygen, nitrogen, hydrogen, and water vapor, and all substances are regarded as ideal gases.

6. The method for calculating the current density distribution of a large-area fuel cell according to claim 5, characterized in that, Step S4 also includes: 4) The fresh cathode air first enters the anode outlet half-cell, reacts in the anode outlet half-cell, then enters the anode inlet half-cell, and then is discharged from the fuel cell; 5) The fresh anode hydrogen first enters the anode inlet half-cell, reacts in the anode inlet half-cell, then enters the anode outlet half-cell, and then is discharged from the fuel cell; 6) Changes in the anode gas concentration or cathode gas concentration will both cause redistribution of the current and voltage inside the fuel cell.

7. A method for calculating the current density distribution of a large-area fuel cell according to claim 1, characterized in that The Nernst potential described above Calculated by the Nernst equation, we have: wherein, is the anode hydrogen partial pressure, is the cathode oxygen partial pressure, , are empirical parameters obtained by parameter identification, respectively; The activation overpotential Calculated by the Tafel semi-empirical formula and Henry's law, we have: Among them, is the oxygen dissolution concentration at the three-phase reaction interface of the cathode catalyst layer, is the actual current of the fuel cell; The ohmic overpotential is the voltage drop caused by the equivalent impedance of protons passing through the exchange membrane and thus: Among them, is the thickness of the proton exchange membrane, A is the effective active area, is the membrane water content, is the empirical parameter obtained by parameter identification; The concentration overpotential mentioned above is calculated by the following formula: Among them, and are empirical parameters obtained through parameter identification respectively, is the natural logarithm.

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