Proton exchange membrane fuel cell and application thereof

Abstract

The invention relates to a proton exchange membrane fuel cell and application thereof, and belongs to the technical field of fuel cells. The proton exchange membrane fuel cell sequentially comprises the following structures: an anode bipolar plate, an anode channel, an anode gas diffusion layer, an anode microporous layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, a cathode microporous layer and a cathode porous metal flow field, wherein a framework of the cathode porous metal flow field has a triple-cycle minimum surface topological structure; and the porosity of the cathode porous metal flow field is greater than 80%. According to the proton exchange membrane fuel cell provided by the invention, the pumping power can be reduced, the gas transportation energy consumption is reduced, redundant heat generated in a system is effectively reduced, and simplification and light weight of thermal management of the system are facilitated; the requirements for the size and power of auxiliary equipment are lower, and the volume power density of the system can be improved; the mechanical wear of the pump can be obviously slowed down, the service life of accessories is prolonged, and the reliability and durability of the system are improved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a proton exchange membrane fuel cell and its applications. Background Technology

[0002] Faced with the depletion of fossil fuels and the environmental crisis, a global energy transition is imperative. Renewable energy sources such as solar and wind power suffer from problems such as mismatch between power generation and consumption, power loss, and curtailment due to their intermittency and uneven geographical distribution. Hydrogen, as a zero-carbon, highly efficient secondary energy carrier, can solve these problems. Proton exchange membrane fuel cells (PEMFCs) can directly convert hydrogen hydrogen energy into electrical energy, without being limited by the Carnot cycle, and have high actual operating efficiency. Their high efficiency and clean characteristics make them a key technological path for hydrogen energy utilization.

[0003] PEMFCs generate electricity through a hydrogen-oxygen coupled electrochemical reaction. Hydrogen dissociates into protons and electrons at the anode. Protons migrate to the cathode via a perfluorosulfonic acid proton exchange membrane, while electrons form an electric current through an external circuit. Oxygen combines with protons and electrons to form water, avoiding combustion heat loss throughout the process. The core of each cell consists of seven layers, with the flow field topology directly determining reactant transport efficiency, water management capabilities, and output stability. The cathode flow field is particularly critical due to the high activation energy and slow kinetic rate of the oxygen reduction reaction (ORR), as well as the high resistance to oxygen diffusion and the susceptibility to "flooding" caused by water accumulation at the cathode. Traditional serpentine and parallel flow field "channel-rib" structures have inherent defects, leading to uneven gas distribution and drainage difficulties, thus limiting battery performance. To address this issue, researchers proposed a metal foam cathode flow field. Current PEMFCs using a metal foam cathode flow field without a gas diffusion layer face a core bottleneck due to the uncontrollable structure of the metal foam. While its random pore distribution can improve mass transfer and drainage efficiency to some extent, it makes it difficult to accurately simulate microscopic flow behavior. Optimization efforts are limited to macroscopic parameters such as porosity, and cannot achieve fine control over pore shape and connectivity, thus hindering further exploration of battery performance potential. Furthermore, the foam skeleton is prone to stress concentration points under the pressure of stack assembly, leading to structural damage such as interface delamination and crack propagation, directly reducing the reliability of the battery system and shortening its service life.

[0004] Therefore, there is an urgent need to develop a fuel cell based on a highly controllable design of micro-flow field to optimize mechanical performance, enhance the mass and heat transfer efficiency of reactant gases, and significantly reduce performance fluctuations and improve consistency. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a proton exchange membrane fuel cell and its applications. The fuel cell of this invention exhibits stable flow field performance, controllable structure, reduced pump power consumption, increased output power, and functional integration.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a proton exchange membrane fuel cell, characterized in that it comprises the following structures in sequence: an anode bipolar plate, an anode channel, an anode gas diffusion layer, an anode microporous layer, an anode catalyst layer, a proton exchange membrane, a cathode catalyst layer, a cathode microporous layer, and a cathode porous metal flow field, wherein the framework of the cathode porous metal flow field has a triple-period minimum surface topology. The porosity of the cathode porous metal flow field is >80%.

[0007] The proton exchange membrane fuel cell provided by this invention employs a mathematical geometry based on a triple periodic minimum surface (TPMS), resulting in a cathode flow field structure with precisely controllable pore morphology and connectivity. On one hand, the programmable geometry, described by equations, allows for precise setting of the size, shape, and connectivity of the pore distribution during the design phase, fundamentally overcoming performance fluctuations caused by structural randomness. On the other hand, the periodic topology can uniformly transfer assembly loads in terms of mechanical properties, avoiding stress concentration, while also possessing multi-stage yielding characteristics to resist deformation and damage during assembly. In terms of fluid performance, the through-flow channels significantly reduce dead zones and stagnant flow, improving the uniformity of reactant gas distribution and liquid water discharge, thereby enhancing overall battery efficiency and durability.

[0008] Among them, the structural scheme based on the porous metal flow field of the cathode with a porosity of >80% has been verified by numerical simulation. Compared with the traditional metal foam structure with the same porosity, it can effectively improve the overall electrochemical performance of the fuel cell. The structure can achieve the integration of the functions of the cathode bipolar plate and the gas diffusion layer without relying on the traditional gas diffusion layer. It can effectively undertake all the functions required by the traditional gas diffusion layer, including gas distribution, electron conduction, heat conduction, water management and mechanical support, thereby realizing the integrated fusion of the functions of the cathode bipolar plate and the gas diffusion layer. It is suitable for the manufacture of high power density and high stability fuel cell stacks, replacing the traditional discrete cathode bipolar plate and gas diffusion layer, reducing the cell thickness and achieving a stack volume compression ratio of more than 10%.

[0009] The low porosity of the porous metal flow field in the cathode can lead to a reduction in the size of the through-holes, restricting gas transport paths and making it difficult for oxygen to fully penetrate the cathode catalyst layer. Furthermore, channel contraction hinders the timely discharge of produced water, causing liquid water to accumulate in localized areas and impeding further diffusion of reactant gases. This intensified oxygen concentration gradient and liquid water accumulation together result in a significant increase in concentration polarization, reducing output capacity under high-load conditions.

[0010] It should be noted that although the TPMS cathode porous metal flow field in the proton exchange membrane fuel cell of the present invention can completely replace the cathode gas diffusion layer in all functions, the cathode microporous layer is still retained in the present invention. The cathode microporous layer can construct microscale gas channels between the catalyst layer and the TPMS flow field, enhance local gas supply, promote capillary drainage, protect the catalyst layer structure, and maintain the membrane hydration state, which is an essential part to ensure high-performance and stable operation.

[0011] The pore distribution of existing metal foam flow fields exhibits high randomness during manufacturing. While this structure helps improve mass transfer and drainage performance, it also makes it impossible to accurately simulate and predict microscopic flow behavior. This limits optimization efforts to macroscopic parameters such as porosity, preventing precise control of pore shape and connectivity. Due to the randomness of the structure, existing metal foam flow fields are prone to significant performance fluctuations during mass production, failing to guarantee the consistency of gas distribution and mass transfer characteristics across different batches, thus affecting the stability and reliability of the battery system. Furthermore, during assembly and pressurization, existing metal foam materials exhibit stress concentration points in the foam skeleton, which can easily lead to local yielding or plastic deformation, resulting in flow field interface delamination, local peeling, or crack propagation, reducing structural integrity and long-term durability.

[0012] The porous metal flow field of the cathode using the TPMS structure in the battery of this invention has the following key advantages in terms of structure, performance, and integration capability compared to traditional foam structures: 1. More uniform gas diffusion and more complete reaction: The three-dimensional periodic interconnected channels in the TPMS structure form a regular and uniform gas distribution network, which can effectively reduce concentration polarization; 2. Isotropic structure with strong support: Compared with the traditional foam, which has large differences in pore connectivity in three dimensions, the TPMS structure is triaxially equivalent and has stronger compressive and shear resistance. 3. Excellent water management capability: The TPMS structure has continuous and regular three-dimensional channels inside, which can maintain the full hydration of the proton exchange membrane while forming an efficient liquid water migration pathway, effectively promoting the timely discharge of generated water, reducing the risk of local water flooding at the cathode, and ensuring stable operation under high current density. 4. High manufacturing precision and repeatability: High fidelity and morphological consistency are achieved by using additive manufacturing technology, effectively avoiding the problem of irregular pores caused by the randomness of air bubbles.

[0013] The proton exchange membrane fuel cell provided by this invention solves the problems of uncontrollable micro-flow behavior, poor production consistency, and assembly mechanical defects caused by the randomness of the geometric structure of the cathode metal foam flow field in existing proton exchange membrane fuel cells. It also provides a proton exchange membrane fuel cell structure with high controllability, high consistency, and high reliability, laying a technical foundation for the next generation of integrated stack design.

[0014] It should be noted that the proton exchange membrane fuel cell structure defined in this invention does not include all auxiliary components required for practical applications of fuel cell stacks. For example, the gas inlet / outlet manifold (for supplying gas to multiple cells in series or parallel), coolant flow channel (for regulating operating temperature), electrode plates, sealing gaskets, and clamping devices, which are typically found in fuel cell stacks, are all existing known technologies, and those skilled in the art can design and assemble them using conventional methods as needed.

[0015] Preferably, the defining equation of the triple periodic minimum surface topology conforms to one of the following equations (I)-(III): (Ⅰ) cos(x)+cos(y)+cos(z)=t; (II) sin(x)cos(y)+sin(y)cos(z)+sin(z)cos(x)=t; (III)sin(x)sin(y)sin(z)+sin(x)cos(y)cos(z)+cos(x)sin(y)cos(z)+cos(x)cos(y)sin(z)=t; x, y, and z are coordinate variables in three-dimensional space, and t is an isosurface parameter.

[0016] The present invention achieves highly controllable adjustment of pore size, shape and connectivity through a mathematically defined precise three-dimensional geometric structure, thereby significantly improving gas distribution uniformity, mass and heat transfer efficiency and mechanical reliability.

[0017] It should be noted that the selection scheme of the triple-periodic minimum surface described in this invention is not limited to the specific few mentioned above. Those skilled in the art can also use other mathematical surfaces or variations according to actual needs, such as Schoen I-WP type surfaces, Neovius surfaces, Primitive surfaces, F-RD surfaces, and other types of triple-periodic minimum surfaces, or derived surfaces whose porosity or connectivity is locally adjusted through parameter perturbation. Such structures also possess core characteristics such as zero average curvature, continuous continuity, and geometric programmability.

[0018] More preferably, the defining equation of the triple periodic minimum surface topology conforms to sin(x)cos(y)+sin(y)cos(z)+sin(z)cos(x)=t, where x, y, and z are coordinate variables in three-dimensional space, and t is an isosurface parameter.

[0019] More preferably, the minimum periodic unit of the triple periodic minimum surface topology is a cube, and the side length of the cube is 0.2-0.3 mm.

[0020] As a preferred embodiment of the present invention, the side length of the cube is 0.25 mm.

[0021] Preferably, the porosity of the cathode porous metal flow field is 80-90%.

[0022] The porosity range of the specific cathode porous metal flow field in the proton exchange membrane fuel cell of this invention achieves an effective trade-off between gas transport and mechanical support. Compared with traditional metal foam structures with the same porosity, it can significantly improve current density and output power, while reducing pump power to 0.02%-0.04% of output power, exhibiting higher energy efficiency and reaction uniformity, thereby further verifying its ability to completely replace the gas diffusion layer and assume its function.

[0023] On the other hand, it is preferable to control the porosity of the porous metal flow field of the cathode to be between 80-90%. If the porosity is too high, the metal skeleton wall thickness may be too thin, thereby reducing the mechanical strength of the structure and making it difficult to withstand the compressive stress of the fuel cell assembly and the vibration and thermal stress during operation, thus making it impossible to achieve the integration of the structure.

[0024] More preferably, the porosity of the cathode porous metal flow field is 84%.

[0025] Preferably, the pore size of the cathode porous metal flow field is 100-500 μm.

[0026] Preferably, the framework of the cathode porous metal flow field includes at least one of stainless steel, titanium alloy, and nickel-based alloy.

[0027] As a preferred embodiment of the present invention, the framework of the porous metal flow field of the cathode can be made of: stainless steel SS316L, which has low cost, good machinability, and stable mechanical properties, but requires surface coating or chemical passivation to improve acid resistance; titanium alloy Ti6Al4V, which has excellent corrosion resistance and thermal conductivity, and is suitable for high-stability lightweight fuel cell stacks; and Inconel 718 nickel-based alloy, which is resistant to high temperature and strong acid environments, has excellent electrical and thermal conductivity, and is suitable for long-term service and use under harsh environmental conditions.

[0028] The aforementioned materials can simultaneously meet the following requirements: good electrical conductivity to ensure the continuity of electronic pathways; strong corrosion resistance to adapt to acidic gas environments; excellent thermal conductivity to facilitate membrane hydration and thermal management; and the ability to achieve high-precision printing of complex structures, supporting the repetitive manufacturing of TPMS geometries.

[0029] Preferably, the method for preparing the skeleton of the cathode porous metal flow field includes the following steps: deriving the skeleton model based on the definition equation of the triple periodic minimum surface topology, and then preparing it by additive manufacturing to obtain the skeleton of the cathode porous metal flow field.

[0030] Preferably, the method for preparing the framework of the porous metal flow field in the cathode includes the following steps: S1. Generate a mathematical model of the cathode porous metal flow field skeleton according to the defined equation, generate an initial three-dimensional mesh and derive it; the initial three-dimensional mesh is a hollow curved surface structure; S2. Perform post-processing on the exported initial 3D mesh, and then fill the internal cavity to obtain the solid model; S3. Import the solid model into the additive manufacturing equipment for additive manufacturing, and after solid post-processing, obtain the skeleton solid of the cathode porous metal flow field.

[0031] More preferably, in S2, the model post-processing includes cleaning and simplification using an edge folding algorithm based on quadratic surfaces.

[0032] More preferably, in S3, the post-processing of the solid includes at least one of the following: support removal, hot isostatic pressing, annealing, surface sandblasting, and chemical polishing.

[0033] More preferably, the additive manufacturing process includes at least one of selective laser melting, stereolithography, and electron beam melting.

[0034] It should be noted that the selection of the preparation process of the cathode porous metal flow field skeleton entity described in this invention is not limited to the specific few mentioned above. Those skilled in the art can also use porous metal sacrificial template sintering (such as polymer template impregnation of metal powder sintering), electrochemical deposition (such as electroplating metal on a three-dimensional porous template), 3D jet printing, Binder Jetting, or DLP photocuring metal slurry sintering, etc., as long as the same geometric pore characteristics and porous integrated flow field function as this invention are achieved, they can all be regarded as equivalent technical solutions.

[0035] Preferably, the thickness of the porous metal flow field in the cathode is 0.5-1 mm.

[0036] More preferably, the thickness of the porous metal flow field in the cathode is 0.5 mm.

[0037] The cathode porous metal flow field of the proton exchange membrane fuel cell of the present invention can adopt an overall uniform TPMS structure. Similarly, pore size gradient, porosity gradient or wall thickness distribution can be introduced in three dimensions to form a porous skeleton with locally enhanced drainage or heat conduction function. This gradient design is a reasonable extension of the technical solution of the present invention.

[0038] Secondly, the present invention provides the application of the above-mentioned proton exchange membrane fuel cell in the field of energy supply.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a proton exchange membrane fuel cell and its application, which employs a porous metal flow field of the cathode based on a TPMS structure. Through a mathematically defined precise three-dimensional geometric structure, the pore size, shape, and connectivity are highly controllable and adjustable, thereby significantly improving gas distribution uniformity, mass and heat transfer efficiency, and mechanical reliability. Compared with traditional metal foam structures of the same porosity or solutions with excessively high or low porosity, the solution within a specific porosity range can effectively improve the overall electrochemical performance of the fuel cell. Furthermore, the technical solution provided by this invention can integrate the functions of the cathode bipolar plate and the gas diffusion layer without relying on a traditional gas diffusion layer, making it suitable for the manufacture of high power density and high stability fuel cell stacks. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the proton exchange membrane fuel cell of the present invention in Example 1; Figure 2 This is a schematic diagram of the minimum periodic unit of the cathode porous metal flow field of the proton exchange membrane fuel cell of the present invention in Examples 1-3; Figure 3 The graphs show the current density and power density curves of the proton exchange membrane fuel cells in Examples 1-3 and Comparative Example 1 at different voltages. Figure 4 The graph shows the output power per unit area and pump power of the proton exchange membrane fuel cells in Examples 1-3 and Comparative Example 1 under an operating voltage of 0.6V. Figure 5 The graphs show the current density curves of the proton exchange membrane fuel cells in Examples 1-3 and Comparative Examples 2-4 at different voltages. Detailed Implementation

[0041] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available reagents and materials.

[0042] General definition The term "Triple Periodic Minimal Surface" (TPMS) refers to a class of periodic implicit surfaces with zero average curvature, capable of forming a continuous, interconnected porous network structure in three-dimensional space. Its geometry is precisely defined using the Level Set Equation, enabling highly controllable adjustment of pore shape, size, and connectivity.

[0043] The term "proton exchange membrane fuel cell" (PEMFC) refers to a type of low-temperature fuel cell that uses hydrogen as fuel and oxygen as oxidant, typically operating at temperatures between 60-80°C. Its core component is the membrane electrode assembly (MEA), which utilizes a proton exchange membrane (PEM) for proton conduction, while a catalyst layer promotes the electrochemical reaction, ultimately producing electricity and water. This type of fuel cell offers advantages such as high energy density, fast response, and environmental friendliness, and is widely used in transportation, portable power supplies, and stationary power sources.

[0044] The term "proton exchange membrane" (PEM) refers to the critical electrolyte layer of a fuel cell, made of perfluorosulfonic acid polymers (such as Nafion®) with high proton conductivity, used to conduct protons between the anode and cathode while blocking electron and gas permeation, ensuring reaction separation and charge balance.

[0045] The term "gas diffusion layer" (GDL) refers to a porous carbon paper or carbon cloth located between the bipolar flow field and the catalyst layer, which has multiple functions including uniformly distributing gas, conducting electricity, removing liquid water, and supporting the membrane electrode assembly (MEA).

[0046] The term "bipolar plate" (BP) refers to the conductive plate in a fuel cell, which serves to separate the battery cells and guide gas flow and conduct current.

[0047] The term "catalyst layer" (CL) refers to a porous structure typically coated on both sides of a proton exchange membrane, containing a noble metal (such as platinum) catalyst dispersed on a carbon support, used to catalyze the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR).

[0048] The term "membrane electrode assembly" (MEA) refers to the core component of a PEMFC, which includes a proton exchange membrane, a catalyst layer, and a gas diffusion layer.

[0049] The term "current density" (A / cm²) 2 The current per unit area of ​​an electrode is the magnitude of the current passing through it, and is an important indicator of the output capacity of a fuel cell.

[0050] The term "power density" (W / cm²) 2 The power output per unit area (current density × voltage) represents the power performance of a fuel cell.

[0051] The term "ohmic polarization region" refers to the area on the current-voltage curve of a fuel cell where the voltage drops linearly due to voltage losses caused by the internal resistance of the electrodes, proton exchange membrane, and current collector. It is primarily determined by the ohmic resistance of the materials.

[0052] The term "concentration polarization region" refers to the area in which the diffusion of reactant gases in the electrode is restricted under high current density conditions, leading to a decrease in gas concentration at the electrode surface and a sharp drop in voltage. This is primarily determined by limitations in reactant transport and diffusion capabilities.

[0053] In proton exchange membrane fuel cells, the term "pump power" refers to the energy consumed to drive the flow of gas or liquid in the flow field channels. It is usually contrasted with output power and is a typical auxiliary loss power. The higher the pump power, the less net output power the system can use. Therefore, reducing pump power is of great significance for improving the overall efficiency and energy utilization of fuel cells.

[0054] Example 1 One embodiment of the proton exchange membrane fuel cell of the present invention, the structure of the proton exchange membrane fuel cell provided in this embodiment is as follows: Figure 1 As shown, it consists of three views: a perspective view of the overall structure, a magnified partial view of the flow field, and a magnified view of the layered structure of the membrane electrode assembly (MEA).

[0055] The main structure of the proton exchange membrane fuel cell in this embodiment includes, in sequence: anode bipolar plate (ABP), anode channel (ACH), anode gas diffusion layer (AGDL), anode microporous layer (AMPL), anode catalyst layer (ACL), proton exchange membrane (PEM), cathode catalyst layer (CCL), cathode microporous layer (CMPL), and cathode porous metal flow field (TPMS-BP). The parameter dimensions of each battery component structure are shown in Table 1 below. Compared with the traditional structure, the thickness of each single cell in this embodiment is reduced from 0.79 mm to 0.69 mm, achieving a stack volume compression ratio of approximately 12.66%.

[0056] Table 1 Depend on Figure 1 The fuel cell structure has the Z-axis as the length direction, the Y-axis as the height direction, and the X-axis as the width direction. During use, hydrogen (H2) flows from the anode side along the positive Z-axis, and oxygen (O2) flows from the cathode side along the negative Z-axis. The two undergo an electrochemical reaction in the membrane electrode assembly (MEA) region. The cathode porous metal flow field's framework has a triple-period minimum surface topology, with a cube with a side length of 0.25 mm as the minimum periodic unit. This unit is periodically assembled in the X, Y, and Z directions, with 4, 2, and 40 units arranged in each direction, respectively. The framework structure conforms to the defined equation cos(x) + cos(y) + cos(z) = t, where x, y, and z are coordinate variables in three-dimensional space, and t is an isosurface parameter. By adjusting the ratio of the fluid domain to the solid domain, the porosity of the cathode porous metal flow field is controlled to 84%. The method for preparing the framework of the porous metal flow field in the cathode includes the following steps: S1. In the MATLAB environment, a three-dimensional boundary mesh model of the unit cell is generated based on the level set equation using custom code to ensure accurate surface definition and complete pore connectivity. Then, the generated initial three-dimensional mesh is exported in stereolithography format for subsequent manufacturing processes. S2. Post-model processing is performed on the exported initial mesh. An edge folding algorithm based on quadratic surfaces is used to clean and simplify the mesh to improve surface smoothness and geometric accuracy, which is conducive to additive manufacturing. The initial mesh only depicts the hollow surface structure of the TPMS lattice. Further solidification processing is performed to fill the internal cavity and transform the thin shell model into a solid model structure with a continuous skeleton. S3. Import the post-processed solid model into the additive manufacturing equipment. Using Inconel 718 nickel-based alloy as raw material, the selective laser melting process of metal powder is adopted: laser power is 150-400W, scanning speed is 600-1200mm / s, scanning distance is 0.08-0.12mm, powder layer thickness is 20-50μm, and metal powder is sintered layer by layer to create a high-precision cathode porous metal flow field skeleton. During the printing process, support structures can be added as needed to ensure the stability of complex geometry. S4. After printing, the workpiece is subjected to support removal, hot isostatic pressing, and annealing to eliminate internal stress, improve mechanical properties and dimensional stability, and then surface sandblasting is performed to improve surface quality.

[0057] The remaining structural layers in the proton exchange membrane fuel cell provided in this embodiment can all be mature commercial fuel cell products, such as microporous layers, catalyst layers, gas diffusion layers, proton exchange membranes, etc. These components have stable industrial production specifications and reliable performance in the market.

[0058] A schematic diagram of the minimum periodic unit of the cathode porous metal flow field in a proton exchange membrane fuel cell is shown below. Figure 2 (a) It can be seen that the prepared porous metal flow field of the cathode has equidistantly distributed spherical cavities and interconnected cylindrical channels inside the framework structure. The fluid can flow uniformly along the inner and outer surfaces of the solid framework simultaneously, and the cross-section is a regular annular shape; combined with Figure 1 The large partial view shows that the white area surrounding the TPMS structural skeleton represents the fluid domain, which represents the transport and distribution of oxygen at the cathode and the extraction of generated water. It clearly shows the continuous and smooth curved pore network of TPMS, with each pore interconnected and its shape precisely controllable, which is different from the non-uniform pore distribution of traditional random metal foam.

[0059] Example 2 The only difference between Example 2 and Example 1 is that the TPMS topology of the cathode porous metal flow field skeleton conforms to the defined equation: sin(x)cos(y)+sin(y)cos(z)+sin(z)cos(x)=t, while the other parameters remain unchanged, and the porosity of the cathode porous metal flow field is controlled to be 84%.

[0060] A schematic diagram of the minimum periodic unit of the cathode porous metal flow field prepared according to the preparation method in Example 1 is shown below. Figure 2 (b) can be seen that the curved structure forms a complex network of spirally interwoven pores with no planar symmetry. The channels extend continuously in three dimensions and form a spiral turbulent layer on the solid surface.

[0061] Example 3 The only difference between Example 3 and Example 1 is that the TPMS topology of its cathode porous metal flow field framework conforms to the defined equation: sin(x)sin(y)sin(z)+sin(x)cos(y)cos(z)+cos(x)sin(y)cos(z)+cos(x)cos(y)sin(z)=t, with other parameters remaining unchanged, the porosity of the cathode porous metal flow field is controlled to be 84%.

[0062] A schematic diagram of the minimum periodic unit of the cathode porous metal flow field prepared according to the preparation method in Example 1 is shown below. Figure 2 (c) It can be seen that the curved structure forms an interwoven channel network with triangular cross sections, the pore distribution is significantly directional, and the fluid flows uniformly along the inner and outer walls of the triangular channels.

[0063] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that a conventional metal foam nickel flow field of the same thickness (porosity 84%, commercially available, labeled Origin) is used instead of the cathode porous metal flow field of the present invention.

[0064] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that, in the preparation of the cathode porous metal flow field framework, the flow field of Example 1 is used as the reference model. By adjusting the wall thickness, the porosity is precisely controlled, and a cathode porous metal flow field with a porosity of 74% is constructed, while keeping the minimum periodic unit size, the structure of the other components of the fuel cell, the material properties and the operating boundary conditions completely consistent.

[0065] Comparative Example 3 The only difference between Comparative Example 3 and Example 2 is that, in the preparation of the cathode porous metal flow field framework, the flow field of Example 2 is used as the reference model. By adjusting the wall thickness, the porosity is precisely controlled, and a cathode porous metal flow field with a porosity of 74% is constructed, while keeping the minimum periodic unit size, the structure of the other components of the fuel cell, the material properties and the operating boundary conditions completely consistent.

[0066] Comparative Example 4 The only difference between Comparative Example 4 and Example 3 is that, in the preparation of the cathode porous metal flow field framework, the flow field of Example 3 is used as the reference model. By adjusting the wall thickness, the porosity is precisely controlled, and a cathode porous metal flow field with a porosity of 74% is constructed, while keeping the minimum periodic unit size, the structure of the other components of the fuel cell, the material properties and the operating boundary conditions completely consistent.

[0067] Example of effect To investigate the application effect of the proton exchange membrane fuel cell provided by this invention, the following tests were conducted: (a) The current density and power density curves of the proton exchange membrane fuel cells in Examples 1-3 and Comparative Example 1 at different voltages were tested using an electrochemical workstation. The operating parameters are shown in Table 2, and the results are as follows: Figure 3 As can be seen, under the same simulation conditions, the fuel cell using a porous metal flow field with a TPMS cathode exhibits higher overall current density and output power compared to the traditional metal foam flow field. For example, at a voltage of 0.4 V, the current densities of different flow fields, from low to high, are as follows: Comparative Example 1 (3.254 A / cm²) 2 Example 3 (3.281 A / cm) 2 Example 1 (3.482 A / cm) 2 Example 2 (3.551A / cm) 2 Compared with the conventional structure of Comparative Example 1, Examples 3, 1, and 2 achieved output power increases of approximately 0.83%, 7.01%, and 9.13%, respectively.

[0068] It should be noted that power density is determined by the product of current density and operating voltage. A higher power density indicates a greater output power per unit area, which has a significant positive effect on improving the volumetric power density of fuel cells, reducing stack size, decreasing system weight, and lowering unit power cost. Therefore, improving power density is an important performance indicator for the engineering application of fuel cells.

[0069] From different voltage ranges, the TPMS structure used in this invention exhibits performance advantages in all typical polarization regions. In the medium current density range (0.8 V–0.6 V), i.e., the ohmic polarization region, the TPMS structure shows superior performance. This advantage mainly stems from the overall increase in oxygen concentration at the interface between the gas diffusion layer (GDL) and the catalyst layer (CL), as well as the improvement in membrane conductivity. On the one hand, the reactants are more uniformly distributed on the electrode surface, promoting the uniformity of the electrochemical reaction, thereby producing a uniform distribution of liquid water; on the other hand, the uniformly distributed water vapor in the gas can more fully penetrate into the membrane interior, maintaining the uniform hydration state of the membrane and effectively reducing ionic resistance. In the high current density range (0.6 V–0.4 V), i.e., the concentration polarization region, the TPMS structure also exhibits excellent performance, indicating its good ability to suppress cathode flooding and oxidant concentration reduction.

[0070] Table 2 (II) The output power per unit area and pump power of the proton exchange membrane fuel cells in Examples 1-3 and Comparative Example 1 were tested using an electrochemical workstation under an operating voltage of 0.6V (assuming a typical pump efficiency of 70% for calculation). The results are as follows: Figure 4 The blue portion represents the fuel cell's output power density, and the pink portion represents the pumping power density. This visually demonstrates the combined performance of different flow field structures in terms of gas transport resistance and output capacity. In the examples, fuel cells employing three different TPMS cathode porous metal flow fields all exhibit significant advantages in pumping power, with pumping power accounting for only a very small proportion of the output power. Specifically, the pumping power of Example 1 is approximately 0.271 W / m³. 2 The proportion is approximately 0.02%; the pump power of Example 2 is approximately 0.481 W / m. 2 The proportion is less than 0.04%; the pump power of Example 3 is approximately 0.270 W / m. 2 The proportion was also approximately 0.02%; in contrast, the pump power of the traditional metal foam flow field dye cell in Comparative Example 1 was as high as 1.81 W / m. 2 The proportion is close to 0.15%, which is significantly higher than that of the TPMS structure in both absolute value and relative proportion. The cathode porous metal flow field with TPMS structure used in this invention has the ability to significantly reduce pump power.

[0071] (III) The current density curves of the proton exchange membrane fuel cells in Examples 1-3 and Comparative Examples 2-4 at different voltages were tested using an electrochemical workstation to investigate the effect of porosity variation on flow field mass transfer characteristics and overall electrochemical performance. The results are as follows: Figure 5As can be seen, a decrease in porosity below 80% generally leads to a decline in fuel cell performance, especially in the high current density region. Taking 0.4V as a representative point, the current densities of Comparative Examples 3 and 2 with 74% porosity are approximately 20.42% and 6.29% lower than the original structures (Examples 2 and 1), respectively. A significant voltage decay appears in the latter part of the polarization curve, indicating that the concentration polarization loss is significantly aggravated.

[0072] The fundamental reason is that reduced porosity means smaller pore sizes within the structure, limiting gas transport paths and making it difficult for oxygen to fully penetrate the cathode catalyst layer. Furthermore, channel contraction hinders the timely discharge of permeable water, causing liquid water to accumulate more easily in localized areas, thus impeding further diffusion of reactant gases. This intensified oxygen concentration gradient and liquid water accumulation together lead to a significant increase in concentration polarization, reducing output capacity under high-load conditions.

[0073] In contrast, the performance change of the cathode porous metal flow field in the original embodiment 3 after the porosity is reduced is relatively small, with its 0.4V current density decreasing by only about 0.61%. This is mainly because the original pore structure of this structure is limited, and the gas transport capacity mainly depends on the baffle turbulence mechanism. Therefore, the effect of porosity change on it is not as significant as the previous two structures.

[0074] Based on the above effect analysis: Traditional metal foams are typically prepared using sacrificial template impregnation, powder sintering, or foaming metallurgical processes. The core processes of these methods all involve melt flow, random bubble distribution, or heterogeneous packing of filler molds. Therefore, after curing, highly random and anisotropic pore distribution is unavoidable. Specifically, the pore size within the metal foam exhibits a wide statistical distribution range. Local areas have high pore density and thin pore walls, easily forming stress concentration points, while other areas have low pore density or closed pores, resulting in discontinuous gas flow paths. Furthermore, the pore connectivity of the metal foam skeleton varies in three dimensions, inevitably leading to differences in channel length and cross-sectional area. This can result in uneven gas distribution, increased local flow resistance, and, under assembly clamping or long-term thermal cycling loads, is prone to local deformation or microcrack propagation, affecting mechanical stability and battery operational consistency.

[0075] In contrast, the proton exchange membrane fuel cell provided by this invention employs a cathode flow field based on a continuous three-dimensional porous metal network with a TPMS structure. The pore geometry is precisely described by mathematical equations, enabling highly controllable pore size, shape, and connectivity at the cell scale (e.g., 0.25 mm). Furthermore, the pores are periodically spliced ​​in the X, Y, and Z directions to form isotropic three-dimensional interconnected channels. By controlling its specific porosity, it exhibits the following significant advantages in mechanical performance: First, uniform stress distribution and smooth transitions of curved elements significantly reduce local stress concentration, enhancing compression and shear stability; second, a multi-stage yielding mechanism, with the metal skeleton undergoing buckling and plastic flow step-by-step during loading, effectively absorbing external impact loads; and third, excellent fatigue resistance under cyclic loading, significantly delaying the initiation and propagation of microcracks. Furthermore, the TPMS structure of the cathode flow field achieves high geometric repeatability through additive manufacturing during the preparation process, eliminating the anisotropy and pore deviation caused by template shrinkage or differences in bubble distribution in traditional foams. This enables the porous metal flow field to have long-term stability and consistency in gas transport, electrical and thermal conductivity, and mechanical properties, significantly improving the overall reliability and service life of mass-produced fuel cell stacks.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A proton exchange membrane fuel cell, characterized in that, The structure comprises the following components in sequence: anode bipolar plate, anode channel, anode gas diffusion layer, anode microporous layer, anode catalyst layer, proton exchange membrane, cathode catalyst layer, cathode microporous layer, and cathode porous metal flow field. The framework of the cathode porous metal flow field has a triple-period minimum surface topology. The porosity of the cathode porous metal flow field is >80%.

2. The proton exchange membrane fuel cell as described in claim 1, characterized in that, The defining equation for the triple-periodic minimal surface topology conforms to one of the following equations (Ⅰ)-(Ⅲ): (Ⅰ) cos(x)+cos(y)+cos(z)=t; (II) sin(x)cos(y)+sin(y)cos(z)+sin(z)cos(x)=t; (III)sin(x)sin(y)sin(z)+sin(x)cos(y)cos(z)+cos(x)sin(y)cos(z)+cos(x)cos(y)sin(z)=t; x, y, and z are coordinate variables in three-dimensional space, and t is an isosurface parameter.

3. The proton exchange membrane fuel cell as described in claim 2, characterized in that, The minimum periodic unit of the triple periodic minimum surface topology is a cube with a side length of 0.2-0.3 mm.

4. The proton exchange membrane fuel cell as described in claim 1, characterized in that, The porosity of the cathode porous metal flow field is 80-90%.

5. The proton exchange membrane fuel cell as described in claim 1, characterized in that, The aperture of the cathode porous metal flow field is 100-500 μm.

6. The proton exchange membrane fuel cell as described in claim 1, characterized in that, The framework of the cathode porous metal flow field includes at least one of stainless steel, titanium alloy, and nickel-based alloy.

7. The proton exchange membrane fuel cell as described in claim 1, characterized in that, The method for preparing the skeleton of the cathode porous metal flow field includes the following steps: deriving the skeleton model based on the definition equation of the triple periodic minimum surface topology, and then preparing it by additive manufacturing to obtain the skeleton of the cathode porous metal flow field.

8. The proton exchange membrane fuel cell as described in claim 7, characterized in that, The additive manufacturing process includes at least one of selective laser melting, stereolithography, and electron beam melting.

9. The proton exchange membrane fuel cell as described in claim 1, characterized in that, The thickness of the porous metal flow field in the cathode is 0.5-1 mm.

10. The application of the proton exchange membrane fuel cell as described in any one of claims 1-9 in the field of energy supply.

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