Bipolar plate structure of air-cooled fuel cell

Abstract

The utility model discloses a bipolar plate structure of an air-cooled fuel cell, which is characterized in that an anode flow field and a cathode flow field are formed on the anode side and the cathode side of the bipolar plate through corrugated foils, the anode flow field and the cathode flow field are separated through a flat separation foil, and sealing components are arranged on two sides of the separation foil to seal the anode flow field and the cathode flow field; the cathode side comprises a cathode frame, the cathode frame is located at the anode current collecting port, and the cathode frame is arranged at the two ends of the cathode corrugated foil and matched with the thickness of the cathode corrugated foil, so that the frame in the MEA assembly is tightly attached, and a cathode flow field is formed. According to the utility model, a cathode and cooling airflow separation technology is adopted, so that the relative humidity of cathode airflow and the voltage performance of the galvanic pile are ensured. The utility model provides an economical and efficient solution for an air-cooled fuel cell system, and is particularly applied to the fields of portable power generation and low-power transportation.

Description

TECHNICAL FIELD

[0001] The utility model belongs to fuel cell preparation technology, concretely relates to a kind of air-cooled fuel cell bipolar plate structure, especially based on corrugated metal foil air-cooled fuel cell bipolar plate structure. BACKGROUND

[0002] Bipolar plate is an important component of fuel cell, provides electrical connection between single cell, separates reaction gas and manages heat and product water utilization. Air-cooled fuel cell has advantages in simple structure and cost-effectiveness, but heat dissipation performance is a key challenge. Traditional bipolar plate is usually made of machine processing graphite or metal foil stamping, heavy in weight, expensive in processing technology, and cannot rely on air cooling to provide optimal heat transfer method for stack. Therefore, air-cooled fuel cell system needs lightweight, economical and efficient bipolar plate preparation method, and has strong heat transfer capacity.

[0003] The utility model uses metal corrugated foil as the base material of air-cooled fuel cell bipolar plate, solves the above limitations of existing bipolar plate. Corrugated structure creates a channel for airflow, increases the surface area of heat transfer and promotes turbulence, further enhances the cooling effect. Commercial corrugated metal foil structure design provides an economical and efficient manufacturing process.

[0004] For low-power (100W-10kW) fuel cell applications, designers must simplify fuel cell system to minimize cost. From the perspective of thermal management, fuel cell system needs to be cooled to release heat generated during reaction process. Traditional fuel cell system uses liquid cooling, but liquid cooling requires additional components such as radiator, coolant pump and ion absorber, which increases overall system cost and complexity compared to relatively more complex bipolar plate design. Air-cooled stack can be directly cooled by air provided by fan or blower, thereby reducing stack and system complexity and cost. But air-cooled solution needs to pass through short cooling flow channel to reduce flow channel pressure drop, that is, by designing polar plate with narrow aspect ratio. At the same time, cooling airflow can also provide necessary oxygen for cathode, without the need for separate cathode air compressor or blower, saving system cost.

[0005] However, the air cooling solution is challenging to control the humidity of the PEM fuel cell, as the proton membrane of the PEM fuel cell needs to be properly humidified to achieve ion conductivity and good cell voltage performance, and product water is generally exchanged from the cathode exhaust to the cathode inlet stream by a humidifier. To this end, the utility model focuses on self-humidification, i.e. relying on the product water generated by the fuel cell reaction to humidify the membrane, so as to achieve the purpose of eliminating the external humidifier. However, the air flow rate required for cooling the full power stack is about 40, which is too large for the amount of water generated by the fuel cell reaction, and it is easy to cause the membrane electrode to be too dry, and the acceptable humidity and membrane ion conductivity cannot be achieved. The utility model uses a metal corrugated foil to guide and distribute the cathode and cooling air, and about 50% of the air flow rate will pass through the cathode side of the foil, so the cathode metering ratio is about 20 (still about 5-10 times higher than required), so the cell performance may be lower than that when the normal metering ratio is 2-4, because the conditions of the cathode will be drier, but more friendly to the fuel cell membrane electrode than when the metering ratio is 40.

[0006] In order to reduce the cost of small power fuel cell system, especially for the fuel cell system cost of small batch production. By using corrugated foil, flat foil, plastic gasket, distribution seal, low mold cost can be maintained, which is beneficial to the cost of small batch production. Utility model content

[0007] The utility model aims at the fact that the existing air-cooled fuel cell technology mostly uses graphite or metal material as the main material of the bipolar plate, which is heavy or has high processing cost; when the metal corrugated foil is used as the main material of the bipolar plate, the cooling flow field or drying problem is not reasonably designed, and the utility model provides a kind of air-cooled fuel cell bipolar plate structure.

[0008] Technical scheme: a kind of air-cooled fuel cell bipolar plate structure, the anode side and cathode side of the bipolar plate are formed by corrugated foil anode, cathode flow field, anode flow field and cathode flow field are separated by flat separation foil, and sealing assembly is arranged on the two sides of separation foil to realize the sealing of anode flow field and cathode flow field;

[0009] The cathode side includes a cathode frame, the cathode frame is located at the anode current collecting port, and the cathode frame is arranged at the two ends of the cathode corrugated foil, cooperates with the thickness of the cathode corrugated foil, to realize the close-fitting arrangement of the frame in the MEA assembly, and form the cathode flow field;

[0010] The cathode flow field also serves as a cooling flow field.

[0011] Further, the current collecting pipe port is an open channel in the stack assembly, for providing air flow for the cathode and cooling;The anode current collecting pipe is composed of a plurality of groups of pipe ports on the stacked bipolar plates.

[0012] Further, the anode corrugated foil is a zigzag offset fin type, allowing hydrogen gas to flow on both sides of the corrugated flow channel; the cathode corrugated foil is a common fin type, promoting shunt and limiting or reducing the drying of the fuel cell.

[0013] Further, the cathode corrugated foil, the anode corrugated foil and the separation foil comprise conductive materials such as stainless steel, aluminum alloy or titanium alloy, and have a wave or peak-valley shape, and are provided with a coating for reducing contact resistance and preventing corrosion of the polar plate.

[0014] Further, the thickness of the cathode corrugated foil, the anode corrugated foil and the separation foil is 0.05-0.2mm.

[0015] Further, in the bipolar plate, the distribution flow channel of the reaction gas comprises a corrugated structure and / or a wave structure based on the surface of the corrugated foil.

[0016] Further, the separation foil is used to prevent the generation of bypass gas flow or cross leakage caused by the side edge of the battery or the anode current collector of the bipolar plate.

[0017] Further, the sealing assembly on the anode side is located on the periphery of the separation foil, and the sealing assembly on the cathode side is located on the cathode frame.

[0018] Beneficial effects: the utility model firstly adopts metal corrugated foil to prepare the anode, the cathode / cooling flow field, the corrugated structure increases the surface area and promotes the turbulent flow, thereby improving the heat transfer efficiency, and the metal foil structure significantly reduces the weight of the bipolar plate. A flat separation foil is placed between the anode and the cathode / cooling corrugated foil, which is used to separate the gas flow and support the sealing element on the corrugated foil, thereby improving the gas distribution channel based on the corrugated structure to achieve uniform distribution of the reactants. Finally, the utility model can be extended to different fuel cell sizes and power outputs. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the overall structure of the double splint of the utility model schematic diagram;

[0020] Figure 2 is the structure explosion schematic diagram of the bipolar plate of the utility model;

[0021] Figure 3 is the structure schematic diagram of the anode side of the bipolar plate of the utility model;

[0022] Figure 4 is the zigzag offset fin type corrugated foil structure of the anode side;

[0023] Figure 5 is the membrane electrode MEA plane schematic diagram;

[0024] Figure 6This is a schematic diagram of the cathode-side seal and the cathode frame;

[0025] Figure 7 This is a schematic diagram showing the combination of the cathode, cooling metal corrugated foil, membrane electrode assembly (MEA), and cathode frame.

[0026] Figure 8 It is a common finned corrugated foil structure;

[0027] Figure 9 This is a schematic cross-sectional view of the gas flow channel on the anode side;

[0028] Figure 10 This is a schematic diagram of the cross-section at the cathode / cooling gas flow channel. Detailed Implementation

[0029] To provide a detailed description of the technical solution disclosed in this utility model, further details are provided below with reference to the accompanying drawings.

[0030] First, the bipolar plate described in this invention uses corrugated metal foil for the anode and cathode. An anode flow field is constructed on the anode side based on the corrugated foil, and a cathode / cooling flow field is constructed on the cathode side. These flow fields extend to their respective manifold openings. For example... Figures 1-10 As shown, the bipolar plate of this utility model includes an anode corrugated foil 1 and a cathode corrugated foil 2. A flat separating foil 3 is disposed between the anode corrugated foil 1 and the cathode corrugated foil 2. A sealing assembly 4 is disposed between the separating foil 3 and the anode corrugated foil 1 or the cathode corrugated foil 2. The sealing assembly 4 on the anode side is arranged around the separating foil 3, such as... Figure 3 As shown, the sealing assembly 4 on the cathode side is located at the cathode frame 5, which is situated at both ends of the cathode corrugated foil 2. Figure 7 As shown. The bipolar plate structure also includes an MEA assembly 6, which includes a bottom frame 601, the two ends of which are connected to the cathode frame 5.

[0031] Specifically, in the bipolar plate structure described in this utility model, for the cathode / cooling airflow, the current collector opening is an open space within the fuel cell assembly, while the anode current collector is formed by the openings on multiple stacked bipolar plates. For example... Figure 9 and Figure 10 As shown, for cathode air intake, this invention can provide fresh airflow to both the cathode and cooling simultaneously using a single fan or blower.

[0032] Corrugated metal foil: This type of foil uses thin conductive metal foil, such as stainless steel, titanium, or aluminum alloy, with a corrugated sheet thickness of 0.05-0.2mm. The foil is rolled by machine to create a wavy or peak-and-valley structure. The advantage of using metal foil is that it reduces the height dimension of the fuel cell stack, as well as its volume and weight.

[0033] The corrugated structure of the anode and the cathode forms a cooling airflow channel on the anode side and the cathode / cooling side of the bipolar plate. The conventional corrugated structure can have various shapes (including sine, trapezoidal, rectangular) and sizes (wavelength, wave height) to optimize heat transfer and airflow pressure drop. The utility model structures the conventional corrugated structure for the cathode / cooling flow channel, forms a shunt of the cathode and the cooling airflow, reduces the volatilization of the cathode product water, and forms a self-humidification mechanism. There are many unconventional corrugated structures, and the utility model structures the corrugated structure of the sawtooth-shaped offset fin type ( Figure 4 ) in the anode flow channel of the bipolar plate, allowing airflow to pass from both sides of the corrugated groove, and enhancing the strength of the electrochemical reaction.

[0034] Secondly, the utility model places a piece of flat metal foil (separation foil 3) between the anode and the cathode / cooling two metal corrugated foils to separate the airflow and support the sealing assembly 4 on the corrugated plate. The membrane electrode assembly (MEA assembly 6) contains a bonded frame 601, the thickness of which matches the thickness of the compressed MEA assembly 6. The cathode frame 5 around the anode manifold port acts as a gasket to match the thickness of the cathode / cooling corrugated foil (cathode corrugated foil 2).

[0035] As shown in the combination Figure 5 , the MEA assembly 6 contains a standard proton membrane, catalyst, sub-gasket and GDL assembly. Each side of the MEA assembly is formed into a frame 601 by bonding and seals this interface with adhesive; the thickness of the frame 601 is equal to the thickness of the compressed gas diffusion layer GDL, and the compressed active area of the MEA should have the same thickness as the edge with the frame.

[0036] The cathode frame 5 has a sealing assembly 4 around the current collecting port. The sealing assembly here compresses the edge of the MEA assembly 6, preventing bypass leakage and supporting part of the anode seal. The thickness of the cathode frame 5 plus the compressed seal should be equal to the thickness of the cathode corrugated foil 2. The cathode frame 5 with the seal is bonded to the MEA frame (frame 601) with adhesive. This bonding process requires sealing this interface.

[0037] Gas distribution channels: on the fuel cell reaction side of the bipolar plate, form distribution channels for reaction gases, including hydrogen, cathode air, cooling air. These channels are integrated into the corrugated or wavy structure, or can be composed of separate features, such as embossed or etched patterns on the surface of the metal foil, or use of punched or mesh material structure, or add an insert to adjust the gas pressure drop. The design of the gas distribution channel is crucial for uniform reactant distribution and efficient electrochemical reaction. The wavy cathode and cooling inserts (fins) are fixed in place to be assembled to the MEA assembly 6 with adhesive.

[0038] Manifolds: Air flow in and out for cathode / cooling side and hydrogen flow in and out for reaction side (anode). These manifolds can be manifold bars that fluidically direct into and out of flow channels on bipolar plates.

[0039] Seals: The present application uses the seals on the separator foils to constrain the cell perimeter and the anode manifold, preventing the creation of bypass air flow or cross-over leaks. The seal assembly 4 on the separator foil 3 is able to support the cathode manifold, while the seal assembly 4 at the cathode frame 5 supports the seal of the cell perimeter. This ensures proper sealing and prevents the occurrence of bypass flow or cross-over leaks.

[0040] The preferred way is to have the aspect ratio of the bipolar plate of the present application relatively narrow, i.e. to provide shorter flow channels for the cathode and cooling flow channels, thereby minimizing the pressure drop of air.

[0041] Finally, the anode corrugated foil is preferably of the zigzag offset fin type, as shown in Figure 4 allowing hydrogen to flow on both sides of the corrugated flow channels. While the corrugated foil for the cathode / cooling flow field is of the common type fin, Figure 8 as shown, providing the possibility of shunt to minimize the drying of the fuel cell. In addition, the corrugated foil and the flat separator foil are electrically conductive (e.g. stainless steel or aluminum alloy or titanium alloy) and are covered with a coating to reduce contact resistance and prevent corrosion of the bipolar plate. The present application utilizes the zigzag offset fin type corrugated foil insert to provide preformed anode flow channels and to promote the diffusion of hydrogen in the active area and the removal of product water from the active area, reducing the possibility of reverse polarity due to hydrogen starvation. The positioning of the anode insert is preferably using adhesive, but can be welded with the separator foil.

[0042] The bipolar plate of the present application forms a forced air fuel stack / battery, where the cathode flow field and the cooling flow field can be supplied with air for the cathode and cooling by one blower, thereby simplifying the system and reducing cost. The corrugated foils in the flow field extend to the manifold ports, providing flow paths and passages from the manifold through the seal assembly to the active area, and a flat separator foil is placed between the anode and the cathode / cooling corrugated foils to separate the gas flows and support the seal assembly on the corrugated foils.

Claims

1. A bipolar plate structure for an air-cooled fuel cell, characterized in that, The bipolar plate forms anodic and cathode flow fields on both the anode and cathode sides through corrugated foil. The anodic and cathode flow fields are separated by a flat separation foil. Sealing components are provided on both sides of the separation foil to seal the anodic and cathode flow fields. The cathode side includes a cathode frame, which is located at the anode collector and is placed at both ends of the cathode corrugated foil. The cathode frame is matched with the thickness of the cathode corrugated foil to achieve a tight fit between the frame and the frame in the MEA assembly, forming a cathode flow field. The cathode flow field also serves as the cooling flow field.

2. The air-cooled fuel cell bipolar plate structure according to claim 1, characterized in that, For cathode airflow, the collector port is an open channel within the fuel cell assembly used to provide airflow for the cathode and cooling; the anode collector consists of ports on several stacked bipolar plates.

3. The air-cooled fuel cell bipolar plate structure according to claim 1, characterized in that, The anode corrugated foil is a serrated bias fin type, which allows hydrogen to flow on both sides of the corrugated flow channel; the cathode corrugated foil is a regular fin type, which promotes flow splitting and limits or reduces the drying of the fuel cell.

4. The air-cooled fuel cell bipolar plate structure according to claim 3, characterized in that, The cathode corrugated foil, anode corrugated foil, and separation foil are made of conductive materials including stainless steel, aluminum alloy, or titanium alloy, and have a wavy or peak-valley morphological structure. They are covered with a coating to reduce contact resistance and prevent electrode corrosion.

5. The air-cooled fuel cell bipolar plate structure according to claim 1 or 3, characterized in that, The thickness of the cathode corrugated foil, anode corrugated foil, and separation foil is 0.05-0.2 mm.

6. The air-cooled fuel cell bipolar plate structure according to claim 1, characterized in that, In the bipolar plate, the distribution channel for the reactive gas includes a corrugated structure based on the corrugated structure and / or the corrugated foil surface.

7. The air-cooled fuel cell bipolar plate structure according to claim 1, characterized in that, The separation foil is used to prevent bypass airflow or leakage caused by the battery side or anode current collector formed by the bipolar plate.

8. The air-cooled fuel cell bipolar plate structure according to claim 1 or 2, characterized in that, The sealing assembly on the anode side is located around the separation foil, and the sealing assembly on the cathode side is located on the cathode frame.

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