Air-cooled fuel cell stack coupled with three-dimensional porous structure and adaptive oxygen supply method thereof

Abstract

This invention relates to an air-cooled fuel cell stack with a coupled three-dimensional porous structure and its adaptive oxygen supply method. The stack includes multiple membrane electrode assemblies (MEAs), bipolar plates, anode plates, current collectors, and end plates. Each MEA includes a catalyst-coated membrane and gas diffusion layers (GDLs) on both sides. A three-dimensional porous conductive structure layer is disposed between the outer surface of the GDL gas diffusion layer on the cathode side of each MEA and the adjacent bipolar plate. This three-dimensional porous conductive structure layer is made of a porous metallic material with high porosity, high conductivity, high thermal conductivity, and corrosion resistance, and at least a portion of its surface is coated with a catalytic / conductive coating. This invention integrates a high-porosity, high-conductivity / thermal-conductivity, and corrosion-resistant three-dimensional porous material in situ on the cathode side, constructing a multifunctional interface layer that combines physical support, current conduction, thermal diffusion, aqueous phase regulation, and gas redistribution functions. This achieves self-breathing, self-humidification, self-drainage, and synergistic adaptive local micro-reactions. The process is simple and suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of new energy and electrochemical energy conversion technology, specifically a wind-cooled fuel cell stack with a coupled three-dimensional porous structure and its adaptive oxygen supply method. Background Technology

[0002] Currently, air-cooled proton exchange membrane fuel cells have broad application prospects in portable power supplies, drones, and small mobile devices due to their advantages such as simple structure, lightweight system, and fast start-up. However, their performance has long faced three major bottleneck problems: (1) Imbalanced water management, with fluctuations in ambient humidity leading to membrane drying (RH<30%) or flooding (RH>60%), which seriously affects proton conduction and gas diffusion; (2) Limited oxygen mass transfer, with no forced flow channel at the cathode, resulting in a large oxygen partial pressure gradient and severe concentration polarization; (3) High contact resistance and uneven heat distribution, with poor interface contact between the traditional GDL (gas diffusion layer) and bipolar plates, and local hot spots easily causing membrane degradation.

[0003] Existing improvement solutions, such as closed-loop air-cooled reactors, add a semi-sealed enclosure on the cathode side, leaving only two air vents, one inlet and one outlet. The air is not directly exposed to the outside environment. A fan drives the air to be cooled in a closed channel. Although this improves the sealing and thermal management, it introduces additional air ducts, drainage structures, and sealing maintenance costs, sacrificing the simplicity and reliability that the air-cooling system should have.

[0004] However, existing technologies lack the ability to actively regulate the cathode microenvironment and cannot simultaneously achieve moisture retention, oxygen enrichment, enhanced electron / thermal conduction, and mechanical buffering under dynamic operating conditions. Both traditional and closed-loop air-cooled reactors face problems such as water management imbalance, insufficient gas mass transfer, and high interfacial contact resistance.

[0005] To overcome this problem, a novel cathode interface design with adaptive function and strong manufacturing compatibility is needed to break through the inherent limitations of air-cooled reactors, namely "low power density, short lifespan, and high sensitivity". Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a wind-cooled fuel cell stack with a coupled three-dimensional porous structure. By integrating a three-dimensional porous material with high porosity, high electrical / thermal conductivity, and corrosion resistance in situ on the cathode side, a multifunctional interface layer with physical support, current conduction, thermal diffusion, aqueous phase regulation, and gas redistribution functions is constructed. This enables self-breathing, self-humidification, self-drainage, and synergistic self-adaptation of local micro-reactions. Moreover, the process is simple and suitable for large-scale production.

[0007] To achieve the above objectives, a wind-cooled fuel cell stack with a coupled three-dimensional porous structure is designed, including multiple membrane electrode assemblies (MEAs), bipolar plates 6, anode plates, current collectors, and end plates. The MEAs include a catalyst-coated membrane 3 and GDL gas diffusion layers 2 located on both sides of the catalyst-coated membrane 3. A three-dimensional porous conductive structure layer 1 is disposed between the outer surface of the GDL gas diffusion layer 2 on the cathode side of each MEA and the adjacent bipolar plate 6. The three-dimensional porous conductive structure layer 1 is made of a porous metal material with high porosity, high conductivity, high thermal conductivity, and corrosion resistance, and at least a portion of the surface of the three-dimensional porous conductive structure layer 1 is provided with a catalytic / conductive coating 7.

[0008] Furthermore, the three-dimensional porous conductive structure layer 1 has a dual-scale pore structure, comprising a microporous layer 9 and a macroporous layer 10, wherein the microporous layer 9 has a micropore diameter ≤50μm and is used for water locking and providing catalytic sites; the macroporous layer 10 has a macropore diameter ≥200μm and is used for gas convection and liquid water discharge.

[0009] Furthermore, the porous material of the three-dimensional porous conductive structure layer 1 is selected from one or more combinations of titanium felt, thin titanium plate, sintered nickel fiber felt, gradient pore size sintered stainless steel fiber felt, and carbon fiber.

[0010] Furthermore, the catalytic / conductive coating 7 is a platinum, gold, or iridium oxide coating, and the thickness of the catalytic / conductive coating 7 is 5 nm to 200 nm. The catalytic / conductive coating 7 covers the fiber surface of the three-dimensional porous conductive structure layer 1 to enhance the oxygen reduction reaction activity and electron conduction capability.

[0011] Furthermore, the edges of the three-dimensional porous conductive structure layer 1 are treated with grinding, laser chamfering, or plasma passivation to prevent damage to the membrane electrode during assembly.

[0012] Furthermore, the thickness of the three-dimensional porous conductive structure layer 1 is 0.1 mm to 0.5 mm, and the compression resilience modulus of the three-dimensional porous conductive structure layer 1 is 0.5 MPa to 5 MPa, so as to provide interface buffering and reduce contact resistance under stacking pressure.

[0013] The present invention also provides a method for manufacturing an air-cooled fuel cell stack as described above, comprising the following steps: First, selecting a three-dimensional porous material that combines high porosity, high conductivity, high thermal conductivity, and corrosion resistance; second, applying a catalytic / conductive coating 7 to the surface of the three-dimensional porous material to stably maintain its high porosity structure and electrical / thermal conductivity characteristics during long-term operation; subsequently, cutting the coated material into sheet-like units that match the size of the GDL gas diffusion layer 2 in the membrane electrode; during the stack assembly process, stacking one sheet of the above-cut three-dimensional coated material on the cathode side and outside the GDL gas diffusion layer 2 of each membrane electrode; after all the single cell units are stacked in sequence, applying a predetermined pressure for stacking.

[0014] Furthermore, after the pressurization is completed, an airtightness test is conducted within 5 minutes: if the system pressure drop is ≤15kPa and the hydrogen leakage is ≤1SCCM, it is considered qualified and can proceed to the electrochemical performance test stage; the performance test conditions are: hydrogen flow rate 2 SLPM, gas supply pressure 50 kPa, and forced air cooling volume on the cathode side 100 CFM.

[0015] The present invention also provides an adaptive oxygen supply method for an air-cooled fuel cell stack as described above: Under low current density conditions, the three-dimensional structure of the three-dimensional porous conductive structure layer 1 locks in the water generated by the reaction through micropore capillary action, maintaining a high humidity environment in the local area of ​​the membrane electrode; under high current density conditions, the increased water production of the three-dimensional porous conductive structure layer 1 triggers the drainage channel dominated by macropores, while the local temperature rise induces natural convection to enhance oxygen supply, and the surface catalytic / conductive coating 7 is preferentially activated in the high polarization region, realizing a passive adaptive operation mechanism of on-demand oxygen supply and dynamic balance.

[0016] Furthermore, this method requires no external humidifier, drain pump, humidity sensor, or active control unit, and relies entirely on the physical-chemical synergistic effect of the three-dimensional porous structure to achieve in-situ self-regulation of water, air, heat, and electricity.

[0017] Compared with the prior art, the present invention has the following advantages: (1) This invention integrates a three-dimensional porous material with high porosity, high electrical / thermal conductivity and corrosion resistance in situ on the cathode side to construct a multifunctional interface layer that combines physical support, current conduction, thermal diffusion, water phase regulation and gas redistribution functions, effectively realizing the dynamic adaptive regulation of self-breathing oxygen supply, self-humidification maintenance, self-drainage flood prevention and local micro-reaction environment. (2) The present invention can significantly improve the hydrothermal management capability and oxygen mass transfer efficiency of air-cooled fuel cell stacks, effectively reduce interfacial contact resistance and provide mechanical buffering effect. (3) The present invention passesivates the three-dimensional porous material around its perimeter, for example by mechanical grinding, laser chamfering or plasma polishing, to ensure that the edges are smooth and rounded, thereby ensuring the structural safety and long-term reliability of the fuel cell stack and avoiding puncturing the sensitive membrane electrode assembly during assembly or operation. (4) The present invention can significantly improve the electrochemical energy conversion efficiency, and the process is simple and suitable for large-scale production. It solves the problems of insufficient water management, limited oxygen mass transfer and high interfacial contact resistance that are common in existing air-cooled proton exchange membrane fuel cell stacks. It is worth promoting and applying. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the coupling method between the three-dimensional porous material and the membrane electrode of the present invention; Figure 2 This is a schematic cross-sectional view of the three-dimensional porous material of the present invention; Figure 3 This is a comparison diagram of polarization curves in the case of this invention; In the figure: 1. Three-dimensional porous conductive structure layer; 2. GDL gas diffusion layer; 3. Catalyst coating film; 4. Frame 1; 5. Frame 2; 6. Bipolar plate; 7. Catalyst / conductive coating; 8. Platinum particles; 9. Microporous layer; 10. Macroporous layer. Detailed Implementation

[0019] As attached Figure 1 and attached Figure 2 As shown, this invention relates to an air-cooled proton exchange membrane fuel cell stack (PEMFC) without external humidification or external heat spreader. Specifically, it is an air-cooled fuel cell stack with a coupled three-dimensional porous structure, including multiple membrane electrode assemblies (MEAs), a three-dimensional porous structure, bipolar plates 6, anode plates, current collectors, and end plates. The membrane electrode assemblies include a catalyst coated membrane 3 (CCM) and gas diffusion layers 2 located on both sides of the catalyst coated membrane 3. A three-dimensional porous conductive structure layer 1 is disposed between the outer surface of the gas diffusion layer 2 on the cathode side of each membrane electrode and the adjacent bipolar plate 6. The three-dimensional porous conductive structure layer 1 is made of a porous metal material with high porosity, high conductivity, high thermal conductivity, and corrosion resistance, and at least a portion of the surface of the three-dimensional porous conductive structure layer 1 is provided with a catalytic / conductive coating 7. By integrating a three-dimensional porous conductive structure with five functions in one on the cathode side—water locking, gas enhancement, drag reduction, heat spreader, and membrane protection—self-breathing, self-humidification, self-drainage, and synergistic regulation of local micro-reactions are achieved.

[0020] The three-dimensional porous conductive structure layer 1 has a dual-scale pore structure, comprising a microporous layer 9 and a macroporous layer 10. The micropores of the microporous layer 9 have a diameter ≤50μm and are used for water retention and providing catalytic sites. The macropores of the macroporous layer 10 have a diameter ≥200μm and are used for gas convection and liquid water discharge. The porous material of the three-dimensional porous conductive structure layer 1 is selected from one or more combinations of titanium felt, thin titanium plate, sintered nickel fiber felt, gradient pore size sintered stainless steel fiber felt, and carbon fiber.

[0021] The catalytic / conductive coating 7 is a platinum, gold, or iridium oxide coating with a thickness of 5 nm to 200 nm. This coating covers the fiber surface of the three-dimensional porous conductive structure layer 1 to enhance oxygen reduction reaction activity and electronic conductivity. The edges of the three-dimensional porous conductive structure layer 1 are treated with grinding, laser chamfering, or plasma passivation to prevent damage to the membrane electrode during assembly. The thickness of the three-dimensional porous conductive structure layer 1 is 0.1 mm to 0.5 mm, and its compressive resilience modulus is 0.5 MPa to 5 MPa, providing interfacial buffering and reducing contact resistance under stacking pressure.

[0022] The air-cooled proton exchange membrane fuel cell stack of this invention preferably uses titanium felt or titanium mesh as a three-dimensional porous substrate, which can be extended to ultra-thin titanium plates, sintered nickel fiber felt, gradient pore size sintered stainless steel fiber felt, carbon fiber, etc. Compared with existing technologies, this invention can significantly improve the hydrothermal management capability and oxygen mass transfer efficiency of air-cooled fuel cell stacks, effectively reduce interfacial contact resistance, and provide mechanical buffering. Through the synergistic integration of five functions—water locking, gas enhancement, resistance reduction, heat equalization, and membrane protection—it achieves self-breathing oxygen supply, self-humidification maintenance, self-drainage flood prevention, and dynamic adaptive control of the local micro-reaction environment, thereby greatly improving the electrochemical energy conversion efficiency. (See appendix) Figure 1 That is, this air-cooled proton exchange membrane fuel cell stack achieves self-breathing, self-humidification, self-drainage and coordinated regulation of local micro-reactions by integrating a three-dimensional porous conductive structure with five functions in one: water locking, gas enhancement, drag reduction, heat equalization and membrane protection on the cathode side. This results in a power density >1.2 W cm⁻² and a lifespan >20,000 start-stop cycles.

[0023] This invention also provides a method for manufacturing the above-mentioned air-cooled fuel cell stack, comprising the following steps: First, selecting a three-dimensional porous material with high porosity, high electrical conductivity, high thermal conductivity, and excellent corrosion resistance, including but not limited to titanium felt, thin titanium plate, sintered nickel fiber felt, gradient pore size sintered stainless steel fiber felt, and carbon fiber; Second, applying a functional coating, namely a catalytic / conductive coating 7 (such as platinum, gold, or other precious metals), to the surface of the three-dimensional porous material to stably maintain its high porosity structure and excellent electrical / thermal conductivity during long-term operation; Subsequently, cutting the coated material into sheet-like units matching the size of the GDL gas diffusion layer 2 in the membrane electrode; During the stack assembly process, stacking one sheet of the above-cut three-dimensional coated material on the cathode side and outside the GDL gas diffusion layer 2 of each membrane electrode; After all the single cell units are stacked in sequence, applying a predetermined pressure for stacking, and conducting gas tightness and electrical performance tests to verify structural integrity and functional effectiveness. See the appendix for the specific stacking structure. Figure 2 The gas tightness and electrical performance testing procedures are as follows: After the pressurization is completed, a gas tightness test is conducted within 5 minutes: if the system pressure drop is ≤15kPa and the hydrogen leakage is ≤1SCCM, it is considered qualified and can proceed to the electrochemical performance testing stage; the performance testing conditions are: hydrogen flow rate 2 SLPM, gas supply pressure 50 kPa, and forced air cooling airflow on the cathode side 100 CFM.

[0024] The edges of such three-dimensional porous materials are usually quite sharp. To avoid puncturing sensitive membrane electrode components during assembly or operation, they need to be passivated around them, for example by mechanical grinding, laser chamfering or plasma polishing, to ensure that the edges are smooth and rounded, thereby ensuring the structural safety and long-term reliability of the fuel cell stack.

[0025] This invention also provides an adaptive oxygen supply method for an air-cooled fuel cell stack as described above: Under low current density conditions, the three-dimensional structure of the three-dimensional porous conductive structure layer 1 locks in the water generated by the reaction through micropore capillary action, maintaining a high humidity environment in the local area of ​​the membrane electrode; under high current density conditions, the increased water production triggers the drainage channel dominated by macropores, while the local temperature rise induces natural convection to enhance oxygen supply, and the surface catalytic / conductive coating 7 is preferentially activated in the high polarization region, realizing a passive adaptive operation mechanism of on-demand oxygen supply and dynamic balance; this method does not require external humidifiers, drainage pumps, humidity sensors or active control units, and relies entirely on the physical-chemical synergistic effect of the three-dimensional porous structure to achieve in-situ self-regulation of water, gas, heat and electricity.

[0026] The present invention will be further described below with reference to specific comparative examples and embodiments: Example 1 (Control Group) Prepare 6 membrane electrode assemblies (MEA) suitable for air-cooled fuel cell stacks (GDL size: 45 mm × 70 mm), 6 bipolar plates, 1 anode plate, and auxiliary components required for stack assembly, including cathode / anode end plates, current collector plates, power cables, fastening screws, insulating gaskets, torque wrenches, and special stack assembly tooling, etc.; During assembly, first place the cathode end plate and the cathode current collector plate in sequence at the bottom of the stack assembly tooling; Subsequently, stack layer by layer in the order of "bipolar plate (air-side flow channel facing down) - MEA (anode side facing down, cathode side facing up) - bipolar plate", repeat this unit structure until the assembly of 6 MEAs is completed; Finally, install the anode plate, anode current collector plate, and anode end plate at the top of the stack in sequence; After the entire stack assembly is completed, apply an axial compression force of 2500 N for stack compression; After stack compression, conduct an airtightness test within 5 minutes: If the system pressure drop ≤ 15 kPa and the hydrogen leakage rate ≤ 1 SCCM are considered qualified, then it is judged as qualified and can enter the electrochemical performance test stage; The performance test conditions are: hydrogen flow rate 2 SLPM, supply pressure 50 kPa, and forced air cooling air volume on the cathode side 100 CFM. Under this operating condition, the polarization performance of this fuel cell stack can reach 0.538 V@0.6A / cm². Example 2

[0027] Prepare 6 membrane electrode assemblies (MEA) suitable for air-cooled fuel cell stacks (GDL size: 45 mm × 70 mm), 6 bipolar plates, 1 anode plate, and auxiliary components required for stack assembly, including cathode / anode end plates, current collector plates, power cables, fastening screws, insulating gaskets, torque wrenches, and special stack assembly tooling, etc.; Additionally, cut 6 three-dimensional porous platinum-plated titanium meshes with a size of 45 mm × 70 mm (thickness 0.25 mm, surface evenly plated with a platinum layer with a thickness of 0.1 μm, and overall porosity of about 65%), and polish the edges of all titanium mesh sheets to eliminate sharp corners to prevent damage to the MEA during the assembly process. After processing, set aside for use; During assembly, first place the cathode end plate and the cathode current collector plate in sequence at the bottom of the stack assembly tooling; Subsequently, stack layer by layer in the order of "bipolar plate (air-side flow channel facing down) - MEA (anode side facing down, cathode side facing up) - three-dimensional porous platinum-plated titanium mesh - bipolar plate", repeat this unit structure until the assembly of 6 MEAs is completed; Finally, install the anode plate, anode current collector plate, and anode end plate at the top of the stack in sequence; After the entire stack assembly is completed, apply an axial compression force of 2500 N for stack compression; After stack compression, conduct an airtightness test within 5 minutes: If the system pressure drop ≤ 15 kPa and the hydrogen leakage rate ≤ 1 SCCM are considered qualified, then it is judged as qualified and can enter the electrochemical performance test stage; The performance test conditions are: hydrogen flow rate 2 SLPM, supply pressure 50 kPa, and forced air cooling air volume on the cathode side 100 CFM. Under this operating condition, the polarization performance of this fuel cell stack can reach 0.582 V@0.6A / cm². Example 3

[0028] Prepare 6 membrane electrode assemblies (MEA) suitable for air-cooled fuel cell stacks (GDL size is 45 mm × 70 mm), 6 bipolar plates, 1 anode plate, and auxiliary components required for stack assembly, including cathode / anode end plates, current collectors, power cables, fastening screws, insulating gaskets, torque wrenches, and special stack assembly tooling, etc.; additionally, cut 6 three-dimensional porous platinum-plated titanium felts with a size of 45 mm × 70 mm (thickness 0.1 mm, surface evenly plated with a platinum layer with a thickness of 0.1 μm, and the overall porosity is about 65%), and polish or passivate the edges of all titanium felt pieces to eliminate burrs and sharp edges to prevent damage to the MEA during stacking or operation, and set aside after processing; during assembly, first place the cathode end plate and the cathode current collector in sequence at the bottom of the stack assembly tooling; then stack layer by layer in the order of "bipolar plate (air-side flow channel facing down) - MEA (anode facing down, cathode facing up) - three-dimensional porous platinum-plated titanium felt - bipolar plate", and repeat this unit structure until the assembly of 6 MEAs is completed; finally, install the anode plate, anode current collector, and anode end plate at the top of the stack in sequence; after the entire stack assembly is completed, apply an axial compression force of 2500 N for stack compression; after stack compression, conduct an airtightness test within 5 minutes: if the system pressure drop ≤ 15 kPa and the hydrogen leakage rate ≤ 1 SCCM are considered qualified, then it is determined to be qualified and can enter the electrochemical performance test stage; the performance test conditions are: hydrogen flow rate 2 SLPM, supply pressure 50 kPa, and forced air cooling air volume on the cathode side 100 CFM. Under this working condition, the polarization performance of this fuel cell stack can reach 0.621 V @ 0.6 A / cm². As attached Figure 3 This is the comparison chart of polarization curves for Examples 1 to 3 of the present invention.

[0029] In summary, this invention addresses the common problems of water management imbalance, limited oxygen mass transfer, high interfacial contact resistance, and poor environmental adaptability in traditional air-cooled and closed-loop air-cooled reactors. It discloses an air-cooled fuel cell stack with a coupled three-dimensional rigid porous structure and its adaptive oxygen supply method. This invention integrates a high-porosity, high-conductivity / thermal-conductivity, and corrosion-resistant three-dimensional rigid porous material (such as titanium felt, titanium sheet, sintered nickel fiber felt, gradient sintered stainless steel fiber felt, carbon fiber, etc.) on the outer surface of the cathode-side GDL. The surface is coated with noble metals (such as Pt and Au) to enhance catalytic activity and stability. Simultaneously, its rigid framework reduces contact resistance, homogenizes temperature distribution, and provides mechanical buffering. Through a five-in-one synergistic mechanism of water locking, gas enhancement, resistance reduction, heat homogenization, and film protection, the fuel cell stack achieves dynamic adaptive control of self-breathing oxygen supply, self-humidification, self-drainage to prevent flooding, and local micro-reactions without external humidification or complex drainage structures. Experiments show that under conditions of 2 SLPM hydrogen, 50 kPa, and 100 CFM airflow, a 6-cell fuel cell stack using platinum-plated titanium felt (65% porosity) achieves an output voltage of 0.64 V at a current density of 0.6 A / cm², significantly outperforming traditional structures. This invention features a simple structure, strong process compatibility, and requires no additional sensors or control algorithms. It is suitable for applications requiring lightweight design and high reliability, such as portable power supplies and drones, and possesses promising industrialization prospects.

[0030] All components of this invention are general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods. The core of this invention lies in solving the problems of insufficient cathode water management, low oxygen mass transfer efficiency, and high interfacial contact resistance in existing air-cooled proton exchange membrane fuel cell stacks. This invention achieves a synergistic adaptive mechanism of "self-breathing oxygen supply, self-humidification and moisture retention, self-drainage and flood prevention, and enhanced local micro-reactions" by innovatively coupling a three-dimensional porous material with high porosity, high conductivity, high thermal conductivity, and excellent corrosion resistance on the cathode side, and specifically integrating it with standard components such as membrane electrodes and bipolar plates. This invention significantly improves the operational stability, power density, and environmental adaptability of the fuel cell stack.

[0031] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0033] This invention is not limited to the above-described embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this invention shall be considered equivalent substitutions and shall be included within the scope of protection of this invention.

Claims

1. A wind-cooled fuel cell stack with a coupled three-dimensional porous structure, comprising multiple membrane electrode assemblies, bipolar plates (6), anode plates, current collectors, and end plates, wherein the membrane electrode assemblies comprise a catalyst-coated membrane (3) and GDL gas diffusion layers (2) located on both sides of the catalyst-coated membrane (3), characterized in that: A three-dimensional porous conductive structure layer (1) is provided between the outer surface of the GDL gas diffusion layer (2) on the cathode side of each membrane electrode and the adjacent bipolar plate (6). The three-dimensional porous conductive structure layer (1) is made of a metal porous material with high porosity, high conductivity, high thermal conductivity and corrosion resistance, and at least part of the surface of the three-dimensional porous conductive structure layer (1) is provided with a catalytic / conductive coating (7).

2. The air-cooled fuel cell stack as described in claim 1, characterized in that: The three-dimensional porous conductive structure layer (1) has a dual-scale pore structure. The three-dimensional porous conductive structure layer (1) includes a microporous layer (9) and a macroporous layer (10). The microporous layer (9) has a micropore diameter ≤50μm and is used for water locking and providing catalytic sites. The macroporous layer (10) has a macropore diameter ≥200μm and is used for gas convection and liquid water discharge.

3. The air-cooled fuel cell stack as described in claim 1, characterized in that: The porous material of the three-dimensional porous conductive structure layer (1) is selected from one or more combinations of titanium felt, thin titanium plate, sintered nickel fiber felt, gradient pore size sintered stainless steel fiber felt, and carbon fiber.

4. The air-cooled fuel cell stack as described in claim 1, characterized in that: The catalytic / conductive coating (7) is a platinum, gold or iridium oxide coating, and the thickness of the catalytic / conductive coating (7) is 5nm to 200nm. The catalytic / conductive coating (7) covers the fiber surface of the three-dimensional porous conductive structure layer (1) to enhance the oxygen reduction reaction activity and electron conduction ability.

5. The air-cooled fuel cell stack as described in claim 1, characterized in that: The edges of the three-dimensional porous conductive structure layer (1) are polished, laser chamfered or plasma passivated to prevent damage to the membrane electrode during assembly.

6. The air-cooled fuel cell stack as described in claim 1, characterized in that: The thickness of the three-dimensional porous conductive structure layer (1) is 0.1 mm to 0.5 mm, and the compression resilience modulus of the three-dimensional porous conductive structure layer (1) is 0.5 MPa to 5 MPa, so as to provide interface buffering and reduce contact resistance under stacking pressure.

7. A method for manufacturing an air-cooled fuel cell stack as described in any one of claims 1 to 6, characterized in that, Includes the following steps: First, a three-dimensional porous material with high porosity, high conductivity, high thermal conductivity and corrosion resistance is selected. Second, a catalytic / conductive coating (7) is applied to the surface of the three-dimensional porous material to stably maintain its high porosity structure and conductivity / thermal conductivity during long-term operation. Then, the coated material is cut into sheet units that match the size of the GDL gas diffusion layer (2) in the membrane electrode. During the stack assembly process, a sheet of the above-cut three-dimensional coated material is stacked on the cathode side of each membrane electrode and on the outside of the GDL gas diffusion layer (2). After all the single cell units are stacked in sequence, a predetermined pressure is applied for stacking.

8. The method for manufacturing an air-cooled fuel cell stack as described in claim 7, characterized in that, After the pressurization is completed, an air tightness test is conducted within 5 minutes: if the system pressure drop is ≤15kPa and the hydrogen leakage is ≤1SCCM, it is considered qualified and can proceed to the electrochemical performance test stage; the performance test conditions are: hydrogen flow rate 2 SLPM, gas supply pressure 50 kPa, and forced air cooling volume on the cathode side 100 CFM.

9. An adaptive oxygen supply method for an air-cooled fuel cell stack as described in any one of claims 1 to 6, characterized in that: Under low current density conditions, the three-dimensional porous conductive structure layer (1) locks in the water generated by the reaction through the capillary action of micropores, maintaining a high humidity environment in the local area of ​​the membrane electrode. Under high current density conditions, the increased water production of the three-dimensional porous conductive structure layer (1) triggers the drainage channel dominated by macropores. At the same time, the local temperature rise induces natural convection to enhance oxygen supply. The surface catalytic / conductive coating (7) is preferentially activated in the high polarization region, realizing a passive adaptive operation mechanism of supplying oxygen on demand and dynamic balance.

10. The adaptive oxygen supply method for an air-cooled fuel cell stack as described in claim 9, characterized in that: This method requires no external humidifier, drain pump, humidity sensor or active control unit, and relies entirely on the physical-chemical synergistic effect of the three-dimensional porous structure to achieve in-situ self-regulation of water, air, heat and electricity.

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