A method of manufacturing an air-cooled fuel cell

Abstract

The application discloses a kind of air-cooled fuel cell manufacturing method.Anode is sealed by the pulling force of sealant, cathode is sealed by the elastic force of sealing ring, comprising the following steps: using high viscosity resin to bond membrane electrode and polar plate at anode side sealing ring, i.e. mainly using the viscosity of sealant to seal; The resin includes polyolefin sealant, thermosetting epoxy resin, thermosetting phenolic resin, hot melt adhesive, ethylene-propylene-diene rubber or silicone rubber; For the sealing ring of cathode side, due to the compactness of anode flow channel, elastic sealing is used; That is, cathode sealing groove is formed into sealing rubber ring, and sealing effect is achieved by using the assembly pressure of electric pile. The application reduces the structure, simplifies the preparation process of air-cooled fuel cell, and at the same time reduces the disturbance of pressure-bearing structure to air flow, which is beneficial to improve the performance of electric pile.

Description

Technical Field

[0001] This invention belongs to the field of fuel cells, and specifically relates to a method for manufacturing an air-cooled fuel cell. Background Technology

[0002] Faced with the gradual depletion of fossil fuel resources and the risks of price fluctuations, seeking alternative energy sources has become an inevitable trend. Hydrogen energy, as a clean and efficient secondary energy source, can be produced through water electrolysis and can be produced on a large scale using renewable energy sources such as wind and solar power, which helps to build a sustainable energy system.

[0003] In recent years, significant progress has been made in materials science, electrochemistry, and other fields, providing a solid technological foundation for the development of air-cooled fuel cells. For example, the performance of key components such as novel catalysts, proton exchange membranes, and bipolar plates has been continuously improved, resulting in significant improvements in the efficiency, durability, and cost of air-cooled proton exchange membrane fuel cells (PEMFCs).

[0004] Beyond traditional transportation applications, air-cooled fuel cells are also suitable for small mobile devices such as drones and two-wheeled vehicles, as well as distributed power generation systems. These applications not only require high energy and power densities in the fuel cells but also necessitate simplified system design to reduce costs and improve reliability. Air-cooled fuel cells, with their simple structure, light weight, and lack of complex cooling devices, demonstrate unique appeal in these application scenarios.

[0005] Due to the grid structure on the cathode side of an air-cooled fuel cell, some areas are suspended, resulting in insufficient stress on the membrane electrode assembly frame. To achieve a sealing effect, existing technologies add structures or processes to water-cooled fuel cells. These can be further categorized into three types:

[0006] One type involves adding a pressure-bearing structure to the cathode (such as...). Figure 1 (As shown) (e.g., attaching thickened hard plastic strips, steel strips, etc.) to withstand pressure. This method has a complex process, requires high bonding precision, and the patch obstructs gas flow, which has a significant impact on performance.

[0007] The second type uses a closed cathode design (such as...). Figure 2 As shown in the diagram, two electrode plates are bonded together, forming a closed structure for the airflow channel in the middle. The original grid structure is separated and no longer affects the airtightness. This method is equivalent to processing an additional electrode plate and adding an extra bonding process, increasing material and manufacturing costs.

[0008] The third type involves thickening the frame to increase the pressure of the sealing ring at the suspended point. This method requires high sealing of the membrane electrode, and the thick frame is more likely to damage the proton exchange membrane and gas diffusion layer structure.

[0009] To achieve a sealing effect, the three methods described above partially sacrifice cost and ease of manufacturing, as well as some fuel cell performance. Essentially, they all rely on the elasticity of the sealing ring for sealing. Summary of the Invention

[0010] This invention addresses the characteristics of air-cooled fuel cells, specifically the large grid structure with low air pressure on the cathode side and the small grid structure with high hydrogen pressure on the anode side, by providing a method for sealing the anode using the tensile force of a sealant and sealing the cathode using the elastic force of a sealing ring.

[0011] The technical solution of this invention is as follows.

[0012] A method for manufacturing an air-cooled fuel cell, wherein the anode is sealed by the tensile force of a sealant and the cathode is sealed by the elastic force of a sealing ring, includes the following steps: using a high-viscosity resin to bond the membrane electrode and the electrode plate at the sealing ring on the anode side, i.e., mainly using the adhesiveness of the sealant for sealing; the resin includes polyolefin sealant, thermosetting epoxy resin, thermosetting phenolic resin, hot melt adhesive, EPDM rubber or silicone rubber.

[0013] For the cathode-side sealing ring, due to the tightness of the anode flow channel, an elastic seal is used; that is, a sealing ring is formed in the cathode sealing groove, and the sealing effect is achieved by utilizing the assembly pressure of the fuel cell stack.

[0014] The anode channel has a groove width of less than 0.5 mm and a porosity of less than 50%.

[0015] The anode-side flow channel corresponds to the sealed area, while the cathode-side corresponding area has a planar structure.

[0016] Specifically, the steps include the following:

[0017] (1) Prepare air-cooled electrode plates, membrane electrodes, anode tail plates and cathode tail plates;

[0018] (2) Molding resin at the anode side sealing ring of the air-cooled electrode plate; molding methods include spraying, dispensing, screen printing or high-pressure injection molding;

[0019] (3) After forming, attach the membrane electrode to the anode side of the electrode plate and press it with a pre-pressing fixture;

[0020] (4) Place the tooling, electrode plate, and membrane electrode in an oven at 100-150℃ and cure at high temperature for 1-2 hours to make a single cell; then take out the single cell and let it cool to room temperature.

[0021] (5) Apply thermosetting single-component liquid silicone to the sealing ring on the cathode side of the single cell, place the single cell in an oven at 120-160℃ for 1-3 hours to cure, take out the single cell, stack the prepared single cells, and add surrounding plates, current collectors, end plates and other structures to form an air-cooled fuel cell stack.

[0022] (6) Apply pressure to the stack and lock it to maintain the stack loading force at 10000N, thus producing an air-cooled fuel cell stack.

[0023] In the above method, in step (1), the number of air-cooled electrode plates is 9-59, the number of membrane electrodes is 10-60, and the number of membrane electrodes needs to be one more than the number of bipolar plates. The number of cathode tail plates and anode tail plates is 1 each. The dimensions of the air-cooled electrode plates are: length 150-250mm, width 40-80mm, thickness 2.5-5mm, and the active area of ​​the membrane electrodes is 30-190cm². 2 .

[0024] In the above method, in step (3), the contact surface between the tooling and the electrode plate and the membrane electrode is a plane, and the clamping force is 500-10000N.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] Compared to the first type of existing technology, this invention reduces the structure and simplifies the fabrication process of air-cooled fuel cells. It also reduces the disturbance of airflow by the pressure-bearing structure, which is beneficial to improving the performance of the fuel cell stack. Compared to the second type of existing technology, this invention reduces the processing of one bipolar plate, saving material and manufacturing costs. Compared to the third type of existing technology, this invention can use a thinner membrane electrode frame, thereby improving the performance and durability of the fuel cell stack. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a Type I air-cooled reactor.

[0028] Figure 2 This is a schematic diagram of a Type II air-cooled reactor structure.

[0029] Figure 3 This is a schematic diagram of the air-cooled reactor structure of the present invention;

[0030] Figure 4 This is a schematic diagram of the anode side structure of a bipolar plate;

[0031] Figure 5 This is a schematic diagram of the cathode side structure of a bipolar plate;

[0032] Figure 6 This is a schematic diagram of the anode side structure of a single cell;

[0033] Figure 7 This is a schematic diagram of the cathode structure of a single cell. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0035] The key feature of this invention is the use of a highly viscous resin to bond the membrane electrode and the electrode plate at the anode-side sealing ring, primarily utilizing the adhesive properties of the sealant for sealing. The resin includes polyolefin sealants, thermosetting epoxy resins, thermosetting phenolic resins, hot melt adhesives, EPDM rubber, silicone rubber, etc.

[0036] For the cathode-side sealing ring, due to the tightness of the anode flow channel, an elastic seal is used. That is, a sealing ring is formed in the cathode sealing groove, and the sealing effect is achieved by utilizing the assembly pressure of the fuel cell stack.

[0037] The schematic diagrams of the anode and cathode sides of the bipolar plate in this invention are shown below. Figure 4 and Figure 5 As shown, the structural schematic diagrams of the anode and cathode sides of a single cell are as follows: Figure 6 and Figure 7 As shown.

[0038] To address the issue of channel compactness, the anode channel is required to have a groove width of less than 0.5 mm and a porosity of less than 50%. For example, groove width and depth combinations could be 0.45 mm + 0.6 mm, 0.4 mm + 0.6 mm, etc. The appropriate configuration depends on the type of adhesive used. Generally, higher adhesive hardness allows for greater groove width and porosity. Since this patent involves a graphite fuel cell, the selected adhesive hardness is below A45, thus requiring the anode channel groove width to be less than 0.5 mm and the porosity to be less than 50%.

[0039] The anode-side flow channel is required to have a corresponding sealed area, while the corresponding area on the cathode side is required to have a planar structure.

[0040] Because the types of sealants used for the anode and cathode are different, the air-cooled reactor manufacturing method described in this invention also varies. Side sealants can be broadly classified into: thermosetting sealants, photocurable sealants, and room-temperature curing two-component sealants. Detailed implementation examples are provided using thermosetting and photocurable sealants. It is required that the curing agent selected directly contacts the membrane electrode frame and plates, and that both have strong bonding strength, with a tensile bond strength of not less than 1.2 MPa. The area-to-permeable area ratio of the anode side sealing ring should be not less than 1:10 to ensure sufficient adhesion between the plates and the membrane electrode during fuel cell operation, preventing leakage. The invention will be described in detail below with reference to specific embodiments.

[0041] Example 1 (Thermosetting sealant):

[0042] 1) Prepare 19 air-cooled electrode plates, 20 membrane electrode plates, and one anode and cathode tail plate each;

[0043] 2) The electrode plate dimensions are 190mm*60mm*3mm, and the active area of ​​the membrane electrode is 70cm². 2 ;

[0044] 3) Apply an appropriate amount of thermosetting epoxy resin to the sealing ring on the anode side of the air-cooled electrode plate; the molding method includes, but is not limited to, spraying, dispensing, screen printing, high-pressure injection molding, etc. (dispensing is used in this embodiment).

[0045] 4) After molding, attach the membrane electrode to the anode side of the electrode plate and press it with a pre-pressing fixture. The contact surface between the fixture and the electrode plate and the membrane electrode is flat, and the pressing force is 7000N.

[0046] 5) Place the tooling, electrode plates, and membrane electrode in a 120℃ oven and cure at high temperature for 2 hours to produce a single cell;

[0047] 6) Remove the single battery and allow it to cool to room temperature;

[0048] 7) Apply appropriate amounts of thermosetting, single-component liquid silicone to the sealing ring on the cathode side of the single cell.

[0049] 8) Place the single cell in a 130℃ oven to cure for 1.5 hours, then remove the single cell;

[0050] 9) Stack the prepared single cells and add surrounding plates, current collectors, end plates and other structures to form an air-cooled fuel cell stack;

[0051] 10) Apply pressure to the fuel cell stack and lock it in place to maintain the stack loading force at 10,000 N, thus creating an air-cooled fuel cell stack.

[0052] Example 2 (Photocurable polyolefin):

[0053] 1) Prepare 19 air-cooled electrode plates, 20 membrane electrode plates, and one anode and cathode tail plate each;

[0054] 2) The electrode plate dimensions are 210mm*60mm*3mm, and the active area of ​​the membrane electrode is 900cm². 2 ;

[0055] 3) Apply an appropriate amount of light-cured polyolefin resin to the sealing ring on the anode side of the bipolar plate; the molding method includes, but is not limited to, dispensing, screen printing, high-pressure injection molding, etc. (screen printing is used in this embodiment);

[0056] 4) After molding, place it in a tunnel oven with a wavelength of 50nm for curing for 15 minutes;

[0057] 5) Remove the electrode plate with the formed sealing ring and cover it with another layer of polyolefin sealant; the forming method is the same as the above method.

[0058] 6) Place the membrane electrode above the anode of the electrode plate and the sealing ring, and press it with a pre-pressing fixture; the contact surface between the fixture and the electrode plate and the membrane electrode is flat, and the pressing force is 9000N;

[0059] 7) Place the compressed electrode plate and membrane electrode in a 50nm light-curing tunnel oven for 30 minutes to cure and form a single cell; remove the single cell after curing.

[0060] 8) Apply an appropriate amount of light-cured polyolefin resin to the sealing ring on the cathode side of the single cell;

[0061] 9) Place the single cell in a tunnel oven with a wavelength of 50nm for 15 minutes to cure, then remove the single cell;

[0062] 10) Stack several single cells together and add current collectors, end plates and other structures to form a fuel cell stack;

[0063] 11) Apply pressure to the fuel cell stack and lock it in place to maintain the stack loading force at 12000N, thus creating an air-cooled fuel cell stack.

[0064] Depending on the curing agent, the above-mentioned sealants can be organically combined to form various specific methods for preparing air-cooled fuel cells. The focus of this invention is on using the adhesive force of the sealant to seal the anode side and the elastic force of the sealant to seal the cathode side, which can lead to many embodiments: such as using epoxy + polyolefin resin for sealing the anode and silicone for sealing the cathode; or using epoxy for sealing the anode and polyolefin for sealing the cathode, etc. It is crucial to avoid using adhesive force or elastic force to seal both sides simultaneously.

Claims

1. A method for manufacturing an air-cooled fuel cell, characterized in that, The anode is sealed using the tensile force of a sealant, and the cathode is sealed using the elastic force of a sealing ring. The process includes the following steps: using a highly viscous resin to bond the membrane electrode and the electrode plate at the sealing ring on the anode side, i.e., mainly using the adhesiveness of the sealant for sealing; the resin includes polyolefin sealant, thermosetting epoxy resin, thermosetting phenolic resin, hot melt adhesive, EPDM rubber, or silicone rubber. For the cathode-side sealing ring, due to the tightness of the anode flow channel, an elastic seal is used; that is, a sealing ring is formed in the cathode sealing groove, and the sealing effect is achieved by utilizing the assembly pressure of the fuel cell stack. The anode channel has a groove width of less than 0.5 mm and a porosity of less than 50%. The anode-side flow channel corresponds to the sealed area, while the cathode-side corresponding area has a planar structure.

2. The method for manufacturing an air-cooled fuel cell as described in claim 1, characterized in that, Includes the following steps: (1) Prepare air-cooled electrode plates, membrane electrodes, anode tail plates and cathode tail plates; (2) Molding resin at the anode side sealing ring of the air-cooled electrode plate; molding methods include spraying, dispensing, screen printing or high-pressure injection molding; (3) After forming, attach the membrane electrode to the anode side of the electrode plate and press it with a pre-pressing fixture; (4) Place the tooling, electrode plate, and membrane electrode in an oven at 100-150℃ and cure at high temperature for 1-2 hours to make a single cell; then take out the single cell and let it cool to room temperature. (5) Apply thermosetting single-component liquid silicone to the sealing ring on the cathode side of the single cell, place the single cell in an oven at 120-160℃ for 1-3 hours to cure, take out the single cell, stack the prepared single cells, and add surrounding plates, current collectors, end plates and other structures to form an air-cooled fuel cell stack. (6) Apply pressure to the stack and lock it to maintain the stack loading force at 10000N, thus producing an air-cooled fuel cell stack.

3. The method for manufacturing an air-cooled fuel cell as described in claim 2, characterized in that, In step (1), the number of air-cooled plates is 9-59 pieces, and the number of membrane electrodes is 10-60 pieces. The number of membrane electrodes needs to be 1 more than the number of bipolar plates.

4. The method for manufacturing an air-cooled fuel cell as described in claim 2, characterized in that, In step (1), the number of cathode tail plates and anode tail plates is 1.

5. The method for manufacturing an air-cooled fuel cell as described in claim 2, characterized in that, In step (1), the dimensions of the air-cooled plate are: length 150-250mm, width 40-80mm, and thickness 2.5-5mm.

6. The method for manufacturing an air-cooled fuel cell as described in claim 2, characterized in that, In step (1), the active area of ​​the membrane electrode is 30-190 cm². 2 .

7. The method for manufacturing an air-cooled fuel cell as described in claim 2, characterized in that, In step (3), the contact surface between the tooling and the electrode plate and the membrane electrode is a plane, and the clamping force is 500-10000N.

Images