Assembly method of fuel cell and fuel cell

Abstract

The invention provides an assembly method of a fuel cell and the fuel cell, the assembly method comprises: acquiring first gas diffusion layer information, the first gas diffusion layer information being obtained by performing a contact resistance test on a membrane electrode, the first gas diffusion layer information comprising a mapping relationship between a membrane electrode pressing force and resistance information; second gas diffusion layer information is obtained, the second gas diffusion layer information is obtained by conducting compression characteristic testing on the membrane electrode, and the second gas diffusion layer information comprises the mapping relation between the membrane electrode pressing force and the deformation quantity of a gas diffusion layer; determining assembly process information based on the first gas diffusion layer information and the second gas diffusion layer information, wherein the assembly process information comprises a first pressing force applied to the gas diffusion layer in the fuel cell assembly process; and assembling the fuel cell based on the assembly process information. According to the invention, the problem of poor output performance of the fuel cell caused by inaccurate assembly pressing force of the fuel cell in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell assembly, and in particular, to an assembly method for a fuel cell and a fuel cell. Background Art

[0002] A proton exchange membrane fuel cell (PEMFC) is an efficient and clean energy conversion device, and its core components include a membrane electrode assembly (MEA), a bipolar plate, and a sealant, etc. During the operation of a PEMFC, the pressing force is one of the key factors affecting the battery performance. An appropriate pressing force can ensure good contact between the membrane electrode and the bipolar plate, reduce the contact resistance, and at the same time avoid damage to the membrane electrode or deformation of the gas diffusion layer (GDL) caused by excessive pressing.

[0003] Currently, the design of the pressing force of a PEMFC mostly relies on empirical or experimental methods. Usually, after all parts such as the bipolar plate and the membrane electrode are manufactured, repeated experiments are carried out during the stack assembly process to find the appropriate battery pressing force, or based on the pressing force data of a group of stacks, the pressing force of the fuel cell is optimized by simulation for the second time. The pressing force designed by the above methods may lead to an increase in contact resistance and the GDL layer cannot reach the optimal compression amount. The fuel cell assembled with the above pressing force has problems of decreased output power and reduced thermal stability.

[0004] Aiming at the above problems in the prior art, no effective solution has been proposed yet. Summary of the Invention

[0005] The main object of the present invention is to provide an assembly method for a fuel cell and a fuel cell, so as to solve the problem of poor output performance of the fuel cell caused by inaccurate pressing force during fuel cell assembly in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, an assembly method for a fuel cell is provided. The assembly method includes: obtaining first gas diffusion layer information, the first gas diffusion layer information is obtained by performing a contact resistance test on the membrane electrode, the first gas diffusion layer information includes the mapping relationship between the membrane electrode pressing force and the resistance information, and the resistance information includes the contact resistance between the gas diffusion layer and the bipolar plate; obtaining second gas diffusion layer information, the second gas diffusion layer information is obtained by performing a compression characteristic test on the membrane electrode, the second gas diffusion layer information includes the mapping relationship between the membrane electrode pressing force and the deformation amount of the gas diffusion layer; determining assembly process information based on the first gas diffusion layer information and the second gas diffusion layer information, the assembly process information includes the first pressing force applied to the gas diffusion layer during the fuel cell assembly process; assembling the fuel cell based on the assembly process information.

[0007] Further, determining the assembly process information based on the first gas diffusion layer information and the second gas diffusion layer information includes: obtaining a target contact resistance value, which is the contact resistance value required when the fuel cell is assembled qualified; obtaining the optimal compression amount of the gas diffusion layer; determining the evaluation target information based on the target contact resistance value and the optimal compression amount; determining the first constraint condition based on the first gas diffusion layer information; determining the second constraint condition based on the second gas diffusion layer information; determining the optimization target based on the evaluation target information; performing an optimal design on the optimization target based on the first constraint condition and the second constraint condition to obtain the optimal solution; and determining the assembly process information based on the optimal solution.

[0008] Further, determining the evaluation target information based on the target contact resistance value and the optimal compression amount includes: determining the resistance difference based on the target contact resistance value and the actual value of the contact resistance; determining the compression difference based on the optimal compression amount and the actual value of the compression amount; and performing a weighted calculation on the resistance difference and the compression difference to obtain the evaluation target information.

[0009] Further, assembling the fuel cell based on the assembly process information includes: obtaining the seal information; determining the seal stress based on the seal information; determining that the sum of the seal stress and the first pressing force is the second pressing force, where the second pressing force is the total pressing force required for assembling the fuel cell; and assembling the fuel cell based on the first pressing force and the second pressing force.

[0010] Further, assembling the fuel cell based on the first pressing force and the second pressing force includes: assembling the bipolar plate with a support structure, the membrane electrode, and the seal to obtain an assembly body, where the support structure is used to support the gas diffusion layer to control the compression amount of the gas diffusion layer; and pressing the assembly body until the relative position of the gas diffusion layer and the support structure no longer moves.

[0011] Further, after determining the seal stress based on the seal information, the assembly method includes: obtaining the working pressure of the fuel cell; checking the seal stress based on the working pressure, and in response to the unqualified check, re - determining the seal stress.

[0012] To achieve the above object, according to one aspect of the present invention, a fuel cell is provided. The fuel cell is assembled by using the above - mentioned assembly method. The fuel cell includes a bipolar plate, on which a flow channel structure and a support structure are provided. The support structure is disposed adjacent to the flow channel structure, and the top end face of the support structure is higher than the top end face of the flow channel structure, so that the gas diffusion layer first contacts the support structure and deforms during the compression process and then abuts against the top end face of the flow channel structure.

[0013] Further, the height difference between the top end face of the support structure and the top end face of the flow channel structure is equal to the optimal compression amount of the gas diffusion layer.

[0014] Furthermore, the support structure is a gasket.

[0015] Furthermore, the bottom end of the support structure is connected to the bipolar plate, and the top end of the support structure extends in a direction away from the bipolar plate. The support structure is a rigid rod-shaped structure.

[0016] Applying the technical solution of the present invention, by comprehensively considering the mapping relationship between the membrane electrode pressing force and the resistance information and the mapping relationship between the membrane electrode pressing force and the deformation amount of the gas diffusion layer, and based on the combination of the two to determine the first pressing force, it can ensure good contact between the membrane electrode and the bipolar plate during the assembly process of the fuel cell, and at the same time enable the gas diffusion layer to have an appropriate deformation amount, avoiding over-pressing and insufficient pressing, thereby achieving the technical effect of improving the assembly effect of the fuel cell. This application solves the problem of poor output performance of the fuel cell caused by inaccurate assembly pressing force in the prior art. Description of the Drawings

[0017] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 Shows a schematic flow chart of an embodiment of the assembly method of a fuel cell according to the present invention;

[0019] Figure 2 Shows a schematic diagram of the change of contact resistance under different pressing forces in an embodiment of the assembly method of a fuel cell according to the present invention;

[0020] Figure 3 Shows a schematic diagram of an embodiment of the GDL compression characteristic curve according to the present invention;

[0021] Figure 4 Shows a schematic structural diagram of an embodiment of the overvoltage protection structure on the bipolar plate according to the present invention;

[0022] Figure 5 Shows a schematic overall diagram of an embodiment of the bipolar plate according to the present invention. Detailed Embodiments

[0023] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] It should be noted that the terms "first", "second", etc. in the description, claims and drawings of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that these terms can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order different from those illustrated or described herein. In addition, the terms "comprise" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0026] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many different forms and should not be construed as being limited only to the embodiments set forth herein. It should be understood that these embodiments are provided so that the disclosure of the present application is thorough and complete, and the concept of these exemplary embodiments is fully conveyed to those of ordinary skill in the art. In the drawings, the thickness of layers and regions may be exaggerated for clarity, and the same reference numerals are used to denote the same devices, and thus their description will be omitted.

[0027] A proton exchange membrane fuel cell (PEMFC, Proton Exchange Membrane Fuel Cell) is an efficient and environmentally friendly electrochemical device mainly used to directly convert the chemical energy of hydrogen and oxygen into electrical energy. Its basic structure and working principle are as follows:

[0028] A PEMFC mainly consists of several parts:

[0029] 1. Proton exchange membrane (PEM): This is the core of the fuel cell, a special polymer membrane that only allows protons (H + ) to pass through while blocking the penetration of electrons and gases. Common materials include Nafion, etc.

[0030] 2. Membrane Electrode Assembly (MEA): Located on both sides of the PEM, it consists of an anode, a cathode, and a proton exchange membrane. The anode and cathode are usually based on carbon paper or carbon cloth, coated with catalysts such as platinum or platinum alloys.

[0031] 3. Bipolar Plates: Located on both sides of the MEA, used for conducting electricity, supporting the MEA, and guiding the reaction gases (hydrogen and oxygen) to the reaction area. The flow channel design on the bipolar plates is crucial for gas distribution and thermal management.

[0032] 4. Gas Flow Control System: Used to control the flow rates of hydrogen and oxygen to ensure the fuel cell operates in the optimal state.

[0033] 5. Water and Heat Management System: The operation of the fuel cell generates water and heat. The water and heat management system is used to control the temperature and humidity of the fuel cell to ensure efficient operation and prevent the membrane from drying out or overheating.

[0034] The working principle of the PEMFC is based on the electrochemical reaction of hydrogen and oxygen: Hydrogen decomposes into protons (H + ) and electrons (e - ) under the action of the anode catalyst. Oxygen reacts with protons and electrons to generate water under the action of the cathode catalyst.

[0035] Protons move from the anode to the cathode through the proton exchange membrane, while electrons flow from the anode to the cathode through the external circuit, generating an electric current. The voltage of a single PEMFC unit is relatively low, generally ranging from 0.6V to 1.2V. Multiple units are stacked in series through bipolar plates to form a stack, which can provide the required higher voltage.

[0036] Heat and water are generated during the operation of the fuel cell and must be removed in a timely manner through the water and heat management system to maintain the optimal operating conditions.

[0037] Combined Figures 1 to 5 As shown, according to the specific embodiments of the present application, a fuel cell assembly method is provided. The assembly method includes:

[0038] Step S102, obtaining first gas diffusion layer information, which is obtained by performing a contact resistance test on the membrane electrode. The first gas diffusion layer information includes the mapping relationship between the membrane electrode compression force and the resistance information, and the resistance information includes the contact resistance between the gas diffusion layer and the bipolar plate;

[0039] Step S104, obtaining second gas diffusion layer information, which is obtained by performing a compression characteristic test on the membrane electrode. The second gas diffusion layer information includes the mapping relationship between the membrane electrode compression force and the deformation amount of the gas diffusion layer;

[0040] Step S106: Determine the assembly process information based on the first gas diffusion layer information and the second gas diffusion layer information. The assembly process information includes the first pressing force applied to the gas diffusion layer during the fuel cell assembly process.

[0041] Step S108: Assemble the fuel cell based on the assembly process information.

[0042] Applying the technical solution of the present invention, by comprehensively considering the mapping relationship between the membrane electrode pressing force and the resistance information, as well as the mapping relationship between the membrane electrode pressing force and the deformation amount of the gas diffusion layer, and based on the comprehensive determination of the first pressing force, it can ensure good contact between the membrane electrode and the bipolar plate during the fuel cell assembly process, and at the same time enable the gas diffusion layer to have an appropriate deformation amount, avoiding over-pressing and insufficient pressing, thereby achieving the technical effect of improving the fuel cell assembly effect. This application solves the problem of poor output performance of fuel cells caused by inaccurate pressing force during fuel cell assembly in the prior art.

[0043] Before performing the contact resistance test on the membrane electrode and before performing the contact resistance test on the membrane electrode, it also includes relevant working condition design and selection to make the membrane electrode during the test have the same specifications and working conditions as the battery to be assembled, so that the obtained pressing force can be applied to the assembly process of a large number of batteries in the same batch.

[0044] The method for determining the pressing force and the method for assembling the fuel cell are as follows:

[0045] S1: Determine the design objectives of the stack:

[0046] S101 Power requirement: According to the application scenario (such as automotive, stationary power supply, etc.), determine the required output power W_stack of the stack.

[0047] S102 Membrane electrode input: According to the design objectives, determine the working conditions of the membrane electrode (MEA), including the current density I_mea, the working voltage V_mea, the working temperature T_operation, the relative humidity Rh_H, the working pressure P_operation, the cathode stoichiometric coefficient S_ca, the anode stoichiometric coefficient S_an, etc.

[0048] S103 Estimation of main parameters: Based on the power requirement, estimate the main parameters such as the number of battery cells N_cell, the voltage V_cell, and the current I_cell.

[0049] S2: Organize the material parameters and related mechanical properties of the MEA:

[0050] S201 Material selection: According to the working conditions of the MEA, select appropriate materials (such as proton exchange membrane, catalyst layer, gas diffusion layer GDL, etc.). Among them, the relevant parameters of the GDL are the most important.

[0051] S202 Mechanical property analysis: Obtain the mechanical property parameters of the GDL, such as elastic modulus and Poisson's ratio, through experiments.

[0052] S3. Measurement of the contact resistance between the bipolar plate and the GDL:

[0053] S301 Measure the contact resistance between the GDL and the bipolar plate under different compaction forces. The step size of the pressure change during the test can be customized, ranging from 0.25 to 0.5 MPa. The test ends when the change rate of the contact resistance < 5%.

[0054] S302 Data recording: Record the contact resistance R_contact, with the unit of Ω·cm, to provide a basis for subsequent optimization. 2 。

[0055] Step S3 is the specific step to obtain the information of the first gas diffusion layer.

[0056] S4. Compression property test of the GDL: Compression test: Conduct a compression test on the GDL and record the change in GDL thickness Δh under different pressures. Compression property curve: Plot the compression property curve to determine the optimal compression amount range of the GDL, the compression modulus E_GDL, and the maximum allowable compression amount Δh_max of the GDL.

[0057] Step S3 is the specific step to obtain the information of the second gas diffusion layer.

[0058] S5. Based on the test results of S3 and S4, conduct a comprehensive analysis of the compaction force to determine the compaction force. According to the test results, the contact resistance is an inverse proportional function or a power exponential function of the pressure. The relationship between the contact resistance and the compaction force can also be fitted based on the test curve. Usually, an empirical formula is obtained by fitting the test data:

[0059] R_contact = 1 / A_a × m(i / P) j (1):

[0060] A_a is the area during the test. m, i, and j are parameters determined by experiments, and the parameters need to be determined according to the test results of the GDL and the bipolar plate. P is the compaction force.

[0061] Or use a polynomial for fitting:

[0062] R_contact = a1P + a2P 2 + a3P 3 +……axP x + C (2):

[0063] a1……ax are fitting parameters, and C is a constant.

[0064] The relationship between the pressing force and the GDL compression amount. As a porous elastic material, the compression amount Δh (i.e., the percentage change in thickness) of GDL has a non-linear relationship with the pressing force P, which is commonly described by the power-law model:

[0065] P = K × Δh n (3):

[0066] K: The stiffness coefficient of the GDL material (related to the porosity and fiber structure); the compression hardening index (usually n > 1, reflecting the hardening characteristics of the material with compression deformation).

[0067] During the GDL pressing process, the contact resistance and the GDL compression amount change simultaneously. The pressing forces in equations (1), (2), and (3) are the same. Therefore, the relationship between the contact resistance and the GDL compression amount can also be obtained.

[0068] S501 Comprehensive analysis: Combine the contact resistance and the compression characteristic curve to determine the compression amount that minimizes the contact resistance and optimizes the mechanical properties of GDL.

[0069] S502 Optimization design: According to the determined optimal compression amount, adjust the design parameters of the MEA and the bipolar plate.

[0070] A comprehensive evaluation index U can be defined, which combines the contact resistance and the compression amount of GDL:

[0071] S6. Determine the key characteristics of the sealing structure.

[0072] S601 Sealing material selection: According to the working conditions of the MEA, working pressure, etc.; select a suitable sealing material, which can be silicone rubber, fluororubber, or ethylene propylene diene monomer rubber, to meet the requirements of temperature, humidity, and compression performance of the fuel cell working conditions.

[0073] S602 Key characteristic determination: Determine the key characteristic parameters such as the compression rate, hardness, and elastic modulus of the sealing material through experiments.

[0074] S603 Sealing structure design optimization: The sealing structure can meet the sealing requirements of the fuel cell, ensure good sealing effect, and the sealing force P_seal ≥ the battery working pressure P_operation. Considering engineering requirements, a better sealing force P_seal should be > 3 times the battery working pressure P_operation; the sealing compression rate ε can be selected in the range of 20% - 60%, preferably 30% - 40%.

[0075] S7. A structure with the function of controlling the GDL compression amount can also be designed on the bipolar plate.

[0076] S701 Structural Design: Design specific structures (such as protrusions, grooves, etc.) on the bipolar plate to precisely control the compression amount of the GDL. Ensure that the compression amount of the GDL, Δh_min < Δh < Δh_max, where Δh_min and Δh_max are the minimum and maximum allowable compression amounts of the GDL.

[0077] A comprehensive evaluation index U can be defined, which combines the contact resistance and the compression amount of the GDL:

[0078] U = w1·(R_target - R_contact) 2 + w2·(Δh_optimal - Δh) 2：

[0079] w1 and w2 are weight coefficients used to balance the importance of the contact resistance and the GDL compression amount.

[0080] R_target is the target contact resistance value. Δh_optimal is the optimal compression amount of the GDL.

[0081] The evaluation index U is optimal when two target values are achieved. The stacking process can be optimized according to the deviation of U from zero. Further, determining the assembly process information based on the first gas diffusion layer information and the second gas diffusion layer information includes:

[0082] Obtain the target contact resistance value, which is the contact resistance value required when the fuel cell assembly is qualified;

[0083] The target contact resistance value is also R_target.

[0084] Obtain the optimal compression amount of the gas diffusion layer;

[0085] The optimal compression amount is also Δh_optimal.

[0086] Determine the evaluation target information based on the target contact resistance value and the optimal compression amount; the evaluation target information is U in the above embodiments.

[0087] Determine the first constraint condition based on the first gas diffusion layer information;

[0088] Determine the second constraint condition based on the second gas diffusion layer information;

[0089] Determine the optimization target based on the evaluation target information;

[0090] Based on the first constraint condition and the second constraint condition, optimize the optimization target to obtain the optimal solution;

[0091] Determine the assembly process information based on the optimal solution.

[0092] The method for solving the optimal solution of the optimization objective based on the above constraints can be through an analytical method, such as the Lagrange multiplier method, which can transform the constrained problem into an unconstrained problem for solution by taking derivatives and introducing multipliers.

[0093] In another alternative embodiment, after obtaining the curve of the change in contact resistance under different pressing forces and the compression characteristic curve of the GDL, the process of determining the pressing force is completed by optimizing the comprehensive evaluation index (U). This index (U) combines the contact resistance (R_contact) and the optimal compression amount (\Delta h_optimal) of the GDL, and introduces weight coefficients (w_1) and (w_2) to balance the importance of these two parameters. The definition of the index (U) is as follows:

[0094] [U = w_1\cdot(R_target - R_contact)^2 + w_2\cdot(\Delta h_optimal - \Delta h)^2]:

[0095] Where, (R_target) is the target contact resistance value, and (\Delta h) is the actual compression amount of the GDL under a specific pressing force. The selection of the weight coefficients (w_1) and (w_2) depends on the specific application scenario and priority - if reducing the contact resistance is more important, then (w_1) should be greater than (w_2); vice versa.

[0096] The method for determining the pressing force is as follows:

[0097] Initial setting: First, set (R_target) and (\Delta h_optimal) according to the application requirements, and initially set the values of the weight coefficients (w_1) and (w_2).

[0098] Data collection: Utilize the contact resistance and GDL compression amount data under different pressing forces obtained in steps S3 and S4,

[0099] to form a series of ((P, R_contact, \Delta h)) triples, where (P) is the pressing force.

[0100] Calculate the index (U): For each triple ((P, R_contact, \Delta h)), calculate the corresponding comprehensive evaluation index (U) according to the above formula.

[0101] Find the minimum (U): By analyzing multiple (U) values, find the (P) value that makes (U) the smallest, which usually corresponds to the situation where the contact resistance is close to the target value and the GDL compression amount is close to its optimal compression amount.

[0102] Weight adjustment: If the initial obtained pressing force does not meet the actual requirements, (w_1) and (w_2) can be adjusted, (U) can be recalculated, and a new optimal solution can be searched for. This process may require repeated iteration until a satisfactory pressing force is found. Further, evaluation target information is determined based on the target contact resistance value and the optimal compression amount, including:

[0103] Determine the resistance difference based on the target contact resistance value and the actual value of the contact resistance; the actual value of the contact resistance is also R_contact in the above embodiments.

[0104] Determine the compression difference based on the optimal compression amount and the actual value of the compression amount; the actual value of the compression amount is also Δh in the above embodiments.

[0105] Perform weighted calculation on the resistance difference and the compression difference to obtain the evaluation target information.

[0106] Further, assemble the fuel cell based on the assembly process information, including:

[0107] Obtain the seal information;

[0108] Determine the seal stress based on the seal information;

[0109] Determine that the sum of the seal stress and the first pressing force is the second pressing force, and the second pressing force is the total pressing force required for fuel cell assembly;

[0110] Assemble the fuel cell based on the first pressing force and the second pressing force. The seal stress and the GDL compression force together obtain the pressing force of the battery during fuel cell assembly. In this process, it is necessary to synchronously compress the GDL and the seal, and it is very important to control the height change. The total pressing force of the fuel cell is the sum of the GDL pressing force and the seal pressing force.

[0111] Further, assemble the fuel cell based on the first pressing force and the second pressing force, including:

[0112] Assemble the bipolar plate with a support structure, the membrane electrode, and the seal to obtain an assembly, wherein the support structure is used to support the gas diffusion layer to control the compression amount of the gas diffusion layer;

[0113] Press the assembly until the relative position between the gas diffusion layer and the support structure no longer moves.

[0114] Further, after determining the seal stress based on the seal information, the assembly method includes:

[0115] Obtain the working pressure of the fuel cell;

[0116] Check the seal stress based on the working pressure, and in response to the unqualified check, re-determine the seal stress.

[0117] In an optional embodiment, the process of compaction force design and fuel cell assembly is as follows:

[0118] S1. Determine the design objectives of the stack:

[0119] S101. Design the stack target power W_stack = 240 kW, which is used for heavy-duty fuel cell commercial vehicles or stationary power plants. W_stack = N_cell × I_cell × V_cell. The rated operating point of the initially selected battery membrane electrode is 0.62 V @ 2 A / cm 2 ; The single-cell active area is set to be 350 - 400 cm 2 , and the active area A_cell:

[0120] A_cell = W_stack / N_cell / I_mea / V_cell; A_cell = I_cell / I_mea.

[0121] S102. Input of the membrane electrode: According to the design objectives, determine the working conditions of the membrane electrode (MEA). The rated current density I_mea is 2 A / cm 2 and the rated operating voltage V_mea is 0.62 V. The operating pressure P_operation is 2 - 2.5 bar, preferably 2.5 bar, and the operating pressure is the absolute pressure.

[0122] S103. Estimation of main parameters: Based on W_stack = 240 kW, estimate that the number of single cells in the stack N_cell is 500 - 550; the current I_cell ≤ 760 A. Considering the number of cells, preferably select an active area of 380 cm 2 .

[0123] S2. According to the working conditions of the MEA, determine the material parameters and related mechanical properties of the MEA.

[0124] Material selection: According to the working conditions of the MEA, select appropriate materials, mainly for the proton exchange membrane, catalyst, and gas diffusion layer GDL used in the membrane electrode. In this solution, the compaction force of the fuel cell mainly acts on the bipolar plate, GDL, and seal. Therefore, the MEA selection mainly refers to the parameters of the GDL. At the same time, select typical mechanical parameters of the GDL.

[0125] Table 1 Main parameters of GDL:

[0126]

[0127] S3. Contact resistance measurement:

[0128] Use a contact resistance test bench to measure the contact resistance between the GDL and the bipolar plate, and record the change curve of the contact resistance under different pressing forces to provide a basis for subsequent optimization.

[0129] According to the experiment, the parameters a1……ax in the formula can be fitted, and the appropriate ones are selected. Fuel cells usually control the contact resistance threshold to be < 10 mΩ·cm 2 , preferably the contact resistance threshold < 7 mΩ·cm 2 , and the optimal control is < 5 mΩ·cm 2 , and at the same time, the pressure of 0.6~1 MPa needs to be concerned. During the test of the bipolar plate and the GDL, the contact resistance and the compression of the GDL are synchronized, so there is a strong correlation between the two.

[0130] S4 Measure the compression amount of the GDL under different pressures and record the change curve to provide a basis for subsequent optimization.

[0131] S5. According to the test results of S3 and S4, conduct a comprehensive analysis of the pressing force. We need to consider both the contact resistance and the compression characteristics of the GDL, determine the optimal compression amount Δh_optimal, the compression force F_optimal that minimizes U(F), and find the best compression force. Taking a bipolar plate with an active area of 380 cm 2 as an example, the pressing force borne by the GDL is 38 kN.

[0132] S6. Determine the key characteristics (such as compression rate, hardness) of the sealing structure.

[0133] S601 Selection of sealing material: According to the working conditions of the MEA, select a suitable sealing material. Silicone rubber, fluororubber or ethylene propylene diene monomer rubber can be selected, which can meet the requirements of temperature, humidity and compression performance of the fuel cell working conditions.

[0134] S602 Determination of key characteristics: Measure the key characteristic parameters such as the compression rate, hardness, and elastic modulus of the sealing material through experiments.

[0135] S603 Force on the sealing structure: The sealing structure can meet the sealing requirements of the fuel cell to ensure good sealing effect. The sealing force F_seal > the battery working pressure P_operation. The sealing compression rate ε can be selected in the range of 20%~60%, preferably 30%~40%. Through simulation calculation of the relationship between the sealing stress and the compression amount of the rubber seal, the sealing stress is combined with the GDL compression force during the fuel cell assembly to obtain the pressing force of the battery. In this process, the GDL and the seal need to be compressed synchronously, and the control of the height change is very important. The pressing force borne by the seal is about 7.5 kN~8.1 kN, and the total pressing force of the fuel cell is the sum of the GDL pressing force and the seal pressing force:

[0136] F_total = F_optimal + F_seal, 45.5 - 46.1 kN. F_optimal = 45.5 kN.

[0137] S7. Design a structure with the function of controlling the compression amount of the GDL on the bipolar plate.

[0138] During the pressing process of the fuel cell, both the seal and the GDL are compressed, and there are differences in the compression displacement and the applied pressing force. To avoid overpressure, a support structure is designed to ensure the optimal compression amount of the GDL. Gaskets with the same height of Δh can be used during the pressing process. A better method is to design a corresponding support structure on the bipolar plate. Design a specific support structure to precisely control the compression amount of the GDL. Ensure that the compression amount of the GDL is at the Δh_optimal position. Δh_min < Δh_optimal < Δh_max, where Δh_min and Δh_max are the minimum and maximum allowable compression amounts of the GDL.

[0139] With the set contact resistance target of 8 mΩ·cm 2 , Δh_optimal is 15%, W1 and W2 are 0.5 respectively, and the actual contact resistance is 10 mΩ·cm 2 , Δh is 12%, and calculating the U value gives 5.1. The pressing pressure can be further increased. When the actual contact resistance is 9 mΩ·cm 2 , when Δh is 14%, the U value is approximately 1.

[0140] Adopting the technical solution of the present application provides a method for designing the pressing force of a PEM fuel cell. Based on the relationship between contact resistance, GDL compression amount and pressure, combined with the seal force requirement. Solve the problems existing in the design of pressing force in the prior art. It can provide theoretical guidance for the bipolar plate design or the fuel cell stack design, and at the same time apply this method in the bipolar plate design process and the fuel cell stack assembly process. Achieve better contact performance and battery performance.

[0141] To achieve the above object, according to one aspect of the present invention, a fuel cell is provided. The fuel cell includes a bipolar plate, and a flow channel structure and a support structure are provided on the bipolar plate. The support structure is adjacent to the flow channel structure, and the top end face of the support structure is higher than the top end face of the flow channel structure, so that the gas diffusion layer first contacts the support structure and deforms during the compression process and then abuts against the top end face of the flow channel structure.

[0142] Combined with Figure 4 As shown, the assembly method of the fuel cell is described as follows: Figure 4During the process of pressing the gas diffusion layer downward, its bottom plane first comes into contact with the fabricated structure. Since the gas diffusion layer is compressible, it can be continuously pressed downward. At this time, the support structure slowly extends within the boundary dimensions of the GDL layer. As the GDL layer is pressed downward and resisted by the support structure and cannot move, the remaining part of the GDL layer just comes into contact with the peak plane of the bipolar plate flow channel.

[0143] Furthermore, the height difference between the top end face of the support structure and the top end face of the flow channel structure is equal to the optimal compression amount of the gas diffusion layer.

[0144] Furthermore, the support structure is a gasket.

[0145] Furthermore, the bottom end of the support structure is connected to the bipolar plate, and the top end of the support structure extends in a direction away from the bipolar plate. The support structure is a rigid rod-shaped structure.

[0146] For the sake of description, spatial relative terms such as "above", "over", "on the upper surface", "upper" etc. can be used here to describe the spatial positional relationship between a device or feature shown in the figure and other devices or features. It should be understood that spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the figure for the device. For example, if the device in the drawing is inverted, the device described as "above" or "over" other devices or structures will then be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0147] In addition to the above, it should also be noted that when referring to "one embodiment", "another embodiment", "embodiment" etc. in this specification, it means that the specific features, structures or characteristics described in connection with that embodiment are included in at least one embodiment described in the general description of the present application. The same expression appearing in multiple places in the specification does not necessarily refer to the same embodiment. Further, when describing a specific feature, structure or characteristic in connection with any one embodiment, it is intended that implementing such feature, structure or characteristic in connection with other embodiments also falls within the scope of the present invention.

[0148] In the above embodiments, the descriptions of each embodiment have their own focuses. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0149] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for assembling a fuel cell, characterized in that, The assembly method includes: Obtaining first gas diffusion layer information, which is obtained by performing a contact resistance test on a membrane electrode. The first gas diffusion layer information includes the mapping relationship between the membrane electrode pressing force and the resistance information, and the resistance information includes the contact resistance between the gas diffusion layer and the bipolar plate; Obtaining second gas diffusion layer information, which is obtained by performing a compression characteristic test on the membrane electrode. The second gas diffusion layer information includes the mapping relationship between the membrane electrode pressing force and the deformation amount of the gas diffusion layer; Determining assembly process information based on the first gas diffusion layer information and the second gas diffusion layer information. The assembly process information includes the first pressing force applied to the gas diffusion layer during the fuel cell assembly process; Assembling the fuel cell based on the assembly process information.

2. The assembly method of the fuel cell according to claim 1, characterized in that, Determining the assembly process information based on the first gas diffusion layer information and the second gas diffusion layer information includes: Obtaining a target contact resistance value, which is the contact resistance value required for the fuel cell to be assembled qualified; Obtaining the optimal compression amount of the gas diffusion layer; Determining evaluation target information based on the target contact resistance value and the optimal compression amount; Determining a first constraint condition based on the first gas diffusion layer information; Determining a second constraint condition based on the second gas diffusion layer information; Determining an optimization target based on the evaluation target information; Performing an optimization design on the optimization target based on the first constraint condition and the second constraint condition to obtain an optimal solution; Determining the assembly process information based on the optimal solution.

3. The assembly method of the fuel cell according to claim 2, characterized in that, Determining the evaluation target information based on the target contact resistance value and the optimal compression amount includes: Determining a resistance difference based on the target contact resistance value and the actual value of the contact resistance; Determining a compression difference based on the optimal compression amount and the actual value of the compression amount; Performing a weighted calculation on the resistance difference and the compression difference to obtain the evaluation target information.

4. The assembly method of the fuel cell according to claim 1, wherein, Assembling the fuel cell based on the assembly process information includes: Obtaining seal information; Determining a seal stress based on the seal information; Determining the sum of the seal stress and the first pressing force as a second pressing force, and the second pressing force is the total pressing force required for the fuel cell assembly; Assembling the fuel cell based on the first pressing force and the second pressing force.

5. The assembly method of the fuel cell according to claim 4, characterized in that, Assembling the fuel cell based on the first pressing force and the second pressing force includes: Assembling a bipolar plate with a support structure, a membrane electrode, and a seal to obtain an assembly, wherein the support structure is used to support the gas diffusion layer to control the compression amount of the gas diffusion layer; Pressing the assembly until the relative position between the gas diffusion layer and the support structure no longer moves.

6. The assembly method of the fuel cell according to claim 4, characterized in that, After determining the seal stress based on the seal information, the assembly method includes: Obtaining the working pressure of the fuel cell; Checking the seal stress based on the working pressure, and in response to the unqualified check, re-determining the seal stress.

7. A fuel cell, characterized in that, The fuel cell is assembled by using the assembly method described in any one of claims 1 to 6. The fuel cell includes a bipolar plate, on which a flow channel structure and a support structure are provided. The support structure is arranged adjacent to the flow channel structure, and the top end face of the support structure is higher than the top end face of the flow channel structure, so that the gas diffusion layer first contacts the support structure and deforms during the compression process and then abuts against the top end face of the flow channel structure.

8. The fuel cell according to claim 7, wherein The height difference between the top end face of the support structure and the top end face of the flow channel structure is equal to the optimal compression amount of the gas diffusion layer.

9. The fuel cell according to claim 7, characterized in that, The support structure is a gasket.

10. The fuel cell according to claim 7, characterized in that, The bottom end of the support structure is connected to the bipolar plate, and the top end of the support structure extends in a direction away from the bipolar plate. The support structure is a rigid rod-shaped structure.

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