A high-performance fuel cell membrane electrode

Abstract

This invention discloses a high-performance fuel cell membrane electrode assembly (MEA), comprising a MEA body, which consists of a proton exchange membrane, a cathode catalyst layer and an anode catalyst layer disposed on both sides of the proton exchange membrane, and a cathode gas diffusion layer and an anode gas diffusion layer disposed on one side of the cathode catalyst layer and the anode catalyst layer. A pressure-resistant frame is installed on one side of the proton exchange membrane, and an active layer is disposed inside the pressure-resistant frame. The MEA also includes an active unit disposed on the pressure-resistant frame and a pressure detection unit disposed inside the pressure-resistant frame. This high-performance fuel cell MEA utilizes heating wires inside the cavity to generate heat, and rapidly and effectively transfers the heat to the active layer through a heat conversion channel. Under the heat transfer effect of the active layer, the ice layer in the cathode gas diffusion layer can be effectively melted, avoiding the ice layer from hindering the water film transfer. The cathode gas diffusion layer is designed accordingly, and the reaction efficiency of the MEA body is accelerated through this cross-flow method.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a high-performance fuel cell membrane electrode. Background Technology

[0002] A fuel cell is a chemical device that directly converts the chemical energy of fuel into electrical energy; it is also known as an electrochemical generator. Because fuel cells convert the Gibbs free energy portion of the chemical energy of fuel into electrical energy through an electrochemical reaction, they are not limited by the Carnot cycle effect and are therefore highly efficient. In addition, fuel cells use fuel and oxygen as raw materials and have no mechanical transmission parts, so they emit very few harmful gases and have a long service life. Furthermore, fuel cells are energy conversion devices that, according to the electrochemical principle, i.e., the working principle of a galvanic cell, isothermally convert the chemical energy stored in fuel and oxidant directly into electrical energy; therefore, the actual process is a redox reaction.

[0003] The membrane electrode assembly (MEA) is a core component of a proton exchange membrane fuel cell (PEMFC). A MEA typically consists of a proton exchange membrane and electrodes disposed on its two surfaces. The electrodes usually include a catalyst layer and a gas diffusion layer, with the catalyst layer positioned between the gas diffusion layer and the proton exchange membrane. The working principle of the fuel cell MEA is as follows: hydrogen is delivered to the anode via the anode flow channel, and oxygen is delivered to the cathode via the cathode flow channel. The hydrogen is catalytically oxidized, releasing electrons and forming hydrogen ions. These hydrogen ions pass through the proton exchange membrane to the cathode side, while electrons are conducted to the cathode side via an external circuit. Oxygen on the cathode side is reduced by electrons and reacts with the hydrogen ions that have passed through the proton exchange membrane to produce water, which is then discharged. However, in practice, it has been found that when the fuel cell is started in an environment below 0°C, the water generated on the cathode side is prone to freezing, leading to blockage of the gas diffusion layer, hindering the reaction, and reducing fuel cell performance. Therefore, we propose a high-performance fuel cell MEA. Summary of the Invention

[0004] The purpose of this invention is to provide a high-performance fuel cell membrane electrode to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-performance fuel cell membrane electrode assembly, comprising a membrane electrode body, wherein the membrane electrode body comprises a proton exchange membrane, a cathode catalyst layer and an anode catalyst layer disposed on both sides of the proton exchange membrane, and a cathode gas diffusion layer and an anode gas diffusion layer disposed on one side of the cathode catalyst layer and the anode catalyst layer, wherein a pressure-resistant frame is installed on one side of the proton exchange membrane, and an action layer is disposed inside the pressure-resistant frame, wherein the cathode catalyst layer and the cathode gas diffusion layer are located inside the action layer, and further comprising: an action unit disposed on the pressure-resistant frame, the action unit being used to clear ice-covered pores in the cathode gas diffusion layer through the action layer; and a pressure detection unit disposed inside the pressure-resistant frame, the pressure detection unit being used to detect the installation pressure during the installation of the membrane electrode body.

[0006] Preferably, the action unit includes a cavity disposed inside the pressure-resistant frame, and an electric heating wire is disposed inside the cavity, and heat conversion channels for connecting with the two side walls of the action layer are installed on the inner walls of both sides of the pressure-resistant frame.

[0007] Preferably, the action unit includes a connecting frame disposed on the inner walls of both sides of the compression-resistant frame, wherein a transmission plate is installed on both sides of the action layer, and the end of the transmission plate is located inside the connecting frame, and piezoelectric vibrating plates are installed on the top and bottom inner walls of the connecting frame.

[0008] Preferably, the cathode gas diffusion layer is composed of multiple A regions and B regions, wherein the multiple A regions and B regions are distributed equidistantly and alternately on the cathode gas diffusion layer, and the A regions and B regions are respectively a hydrophobic layer and a hydrophilic layer.

[0009] Preferably, both region A and region B are composed of multiple pores, and the contact angle θc of region A is in the range of 90°-150°, while the contact angle θc of region B is in the range of 10°-90°.

[0010] Preferably, the pore size in region A is smaller than the pore size in region B.

[0011] Preferably, the pressure detection unit includes a cavity disposed inside the pressure-resistant frame, and the cavity is located near one of the corners of the pressure-resistant frame. A trapezoidal block one is disposed inside the cavity, and a trapezoidal block two is disposed inside the cavity for sliding connection with trapezoidal block one. A through-post is installed on trapezoidal block one, and the end of the through-post penetrates the inner wall of the cavity and extends to the top of the pressure-resistant frame. A force-receiving panel is installed at the end of the through-post. A magnetic block is installed at the end of trapezoidal block two, and a thick magnet for generating an attractive force on the magnetic block is fixedly installed on the inner wall of the cavity. Trapezoidal block two is slidably connected to the inner wall of the cavity.

[0012] Preferably, the trapezoidal block is equipped with connecting columns at both ends, and a circular hole is provided on the side wall of the compression frame. The end of the connecting column is located in the circular hole and is equipped with a detection panel. The top of the compression frame is provided with a circular groove for sliding connection with the force-bearing panel.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1. This invention utilizes the heating wire inside the cavity to generate heat, and then rapidly and effectively transfers the heat to the working layer through a heat conversion channel. Under the heat transfer effect of the working layer, the ice layer in the cathode gas diffusion layer can be effectively melted, avoiding the ice layer from hindering the water film transfer. Taking advantage of the characteristic of the water film flowing out to the area with low capillary pressure, the cathode gas diffusion layer is designed accordingly so that the water film flows out from area B and the gas flows in from area A. This cross-flow method accelerates the reaction efficiency of the membrane electrode body.

[0015] 2. This invention utilizes a piezoelectric vibrating plate to effectively drive the action layer to vibrate under the action of the transmission plate. The action layer acts on the surface of the cathode gas diffusion layer, causing changes in the internal fiber pores. This effectively solves the problem of ice layer obstructing the outflow of water film. Furthermore, by utilizing the working characteristics of fuel cells, the outflow rate of water film can be effectively accelerated. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the water film flow direction structure of the present invention;

[0017] Figure 2 This is a schematic diagram of the contact angle θc structure in regions A and B of the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of the present invention;

[0019] Figure 4 This is a schematic diagram showing the partial structural separation of the membrane electrode body of the present invention;

[0020] Figure 5 This is a partial structural diagram of the pressure detection unit of the present invention;

[0021] Figure 6 This is a schematic diagram of the pressure detection unit structure of the present invention;

[0022] Figure 7 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0023] Figure 8 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0024] Figure 9 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0025] Figure 10 This is a partial structural diagram of Embodiment 1 of the present invention.

[0026] In the diagram: 1-Membrane electrode body; 11-Proton exchange membrane; 12-Cathode catalyst layer; 13-Anode catalyst layer; 14-Cathode gas diffusion layer; 141-Region A; 142-Region B; 143-Pore; 15-Anode gas diffusion layer; 2-Pressure-resistant frame; 3-Action layer; 4-Action unit; 41-Cavity; 42-Heating wire; 43-Heat conversion channel; 44-Connecting frame; 45-Transmission plate; 46-Piezoelectric vibrator; 5-Pressure detection unit; 51-Cavity; 52-Trapezoidal block one; 53-Trapezoidal block two; 54-Through column; 55-Force-bearing panel; 56-Magnetic block; 57-Thick magnet; 58-Connecting column; 59-Circular hole; 50-Detection panel; 501-Circular groove. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1-10This invention provides a technical solution: a high-performance fuel cell membrane electrode assembly (MEA). This invention addresses the problems in the prior art by making corresponding improvements. When a fuel cell is started in an environment below 0°C, the water generated by the reaction on the cathode side easily freezes, causing blockage of the gas diffusion layer, hindering the reaction and reducing fuel cell performance. This invention addresses these problems by including a MEA body 1, wherein bipolar plates are provided on both sides of the MEA body 1. During installation, the bipolar plates, MEA body 1, and bipolar plates are sequentially stacked on the lower end plate of the already installed insulating plate and current collector plate to form the first single cell. The fuel cell stack is fabricated by repeatedly stacking cells in this manner. Existing auxiliary positioning devices are used to ensure the single cells are aligned. After the single cells are installed, the upper end plate is stacked on top, and pressure is applied using an assembly machine to compress the fuel cell stack. However, in actual operation, the required pressure varies depending on the thickness of the fuel cell stack. Unlike other methods, after being compressed under pressure, the stack of multiple single cells is assembled by installing screws. The membrane electrode body 1 consists of a proton exchange membrane 11, a cathode catalyst layer 12 and an anode catalyst layer 13 disposed on both sides of the proton exchange membrane 11, and a cathode gas diffusion layer 14 and an anode gas diffusion layer 15 disposed on one side of the cathode catalyst layer 12 and the anode catalyst layer 13. A pressure-resistant frame 2 is installed on one side of the proton exchange membrane 11. The side wall of the pressure-resistant frame 2 contacts the bipolar plate during installation. The pressure-resistant frame 2 is made of a high-strength material, and a pressure detection unit 5 is set inside the pressure-resistant frame 2 to detect the applied pressure during the assembly of the membrane electrode. The pressure detection unit 5 can detect the applied pressure during the assembly process to avoid excessive or insufficient pressure. At the same time, an active layer 3 is set inside the pressure-resistant frame 2, and the cathode catalyst layer 12 and the cathode gas diffusion layer 14 are both located inside the active layer 3.

[0029] To address the problems in the background art, this invention provides an action unit 4 inside the pressure-resistant frame 2 for clearing the ice-filled pores 143 within the cathode gas diffusion layer 14 through the action layer 3. The action layer 3 is made of a hydrophobic material, so that when a water film flows out from the pores 143 inside the action layer 3, it forms water droplets within the pores 143 and flows into the flow channel. It should be noted that although some existing assembly pressure devices are equipped with pressure gauges during assembly, since the pressure assembly is done manually, insufficient human control can easily lead to excessive or insufficient pressure near the completion of assembly. Insufficient clamping force can also result in insufficient contact area and contact force between the bipolar plate and the cathode gas diffusion layer 14 and anode gas diffusion layer 15 (hereinafter collectively referred to as GDL), leading to increased contact resistance and decreased stack performance. Simultaneously, the clamping force also affects the porosity 143 of the GDL layer, thereby affecting the water and air permeability of the GDL. Larger compressive forces can cause plastic deformation of the GDL, altering its properties. High pressure also poses a significant risk to the proton exchange membrane 11; the combination of higher pressure and the expansion and contraction process of the proton exchange membrane 11 makes it more prone to cracks and pinholes. Furthermore, studies on the proton exchange membrane 11 show that high pressure accelerates fluoride formation, a major reason for reduced membrane lifespan. To further clarify, the membrane electrode body 1 in this invention is a low-platinum, high-performance membrane electrode body 1, with a Pt mass of 0.05–0.25 mg / cm² per unit area, where Pt / CO:Pt / C = ~3:1. Currently, commonly used catalysts use Pt with a mass of 0.4 mg / cm², and commonly used membrane electrode bodies 1 mainly employ Pt / C, where Pt, as a precious metal, is expensive. This invention, by using a Pt / CO:Pt / C mixture as a catalyst, significantly reduces the amount of Pt used in the catalyst layer while ensuring improved polarization performance, thus lowering the cost of the catalyst layer.

[0030] Specifically, during the assembly of the membrane electrode body 1, the bipolar plate, the action layer 3, the cathode gas diffusion layer 14, the cathode catalyst layer 12, the proton exchange membrane 11, the anode catalyst layer 13, the anode gas diffusion layer 15, and the bipolar plate are placed sequentially on the assembly machine. During the assembly process, the assembly pressure is detected by the pressure detection unit 5 to avoid excessive or insufficient pressure. During use, if the machine is started in a low-temperature environment, the water film in the cathode gas diffusion layer 14 may easily condense into an ice layer. The action unit 4 can effectively utilize the action layer 3 to act on the ice layer in the cathode gas diffusion layer 14, preventing the ice layer from affecting the outflow of the water film.

[0031] The cathode gas diffusion layer 14 is composed of multiple A regions 141 and B regions 142, which are equidistantly and alternately distributed on the cathode gas diffusion layer 14. Regions 141 and 142 are respectively a hydrophobic layer and a hydrophilic layer. Both regions 141 and 142 are composed of multiple pores 143. The contact angle θc of region 141 ranges from 90° to 150°, and the contact angle θc of region 142 ranges from 10° to 90°. Regions 142 with a contact angle θc less than 90° are hydrophilic, while those with a contact angle θc greater than 90° are hydrophobic. The size of the pores 143 in region 141 is smaller than the size of the pores 143 in region 142. Region 142 is the hydrophilic layer. As the water outflow area, since the pore size 143 of region B 142 is larger than that of region A 141, and since capillary pressure is related to capillary action, the stronger the capillary action, the greater the capillary pressure, and the smaller the pore size 143, the stronger the capillary action, it can be concluded that region A 141 is a hydrophobic layer, and the pore size 143 of region B 142 is smaller than that of region A 141, thus its capillary pressure is less than that of region B 142. Water flows out in the direction of lower capillary pressure, while region A 141 is an oxygen inflow layer. Since region A 141 and region B 142 are staggered, the water film is avoided from hindering the input of oxygen, thus accelerating the reaction efficiency of the membrane electrode body 1.

[0032] Example 1: As a further limitation of the present invention, the action unit 4 includes a cavity 41 disposed inside the pressure-resistant frame 2, and an electric heating wire 42 is installed inside the cavity 41. Multiple heat conversion channels 43 for connecting with the side walls of the action layer 3 are installed on the inner walls of both sides of the pressure-resistant frame 2. The heat conversion channels 43 are evenly distributed on the pressure-resistant frame 2. The connection points of the two ends of the heat conversion channels 43 with the side walls of the pressure-resistant frame 2 and the side walls of the action layer 3 are set with a large diameter. The diameter of the middle conveying channel is smaller than the diameters of the two ends, so that the gas containing heat flows out from the cavity 41 and its conveying rate is accelerated through the middle conveying channel, and finally comes into contact with the side walls of the action layer 3. Through this design, the contact area between the gas and the side walls of the action layer 3 is larger. The action layer 3 transfers heat to the cathode gas diffusion layer 14, so that the ice layer inside can melt quickly to form a water film that flows out.

[0033] Example 2: The action unit 4 includes a connecting frame 44 fixedly installed on the inner walls of both sides of the pressure-resistant frame 2. A transmission plate 45 is fixedly installed on both sides of the action layer 3, and the end of the transmission plate 45 is located inside the connecting frame 44. Piezoelectric vibrating plates 46 are installed on the top and bottom inner walls of the connecting frame 44. In a low-temperature environment, the water film in the cathode gas diffusion layer 14 is frozen. At this time, the piezoelectric vibrating plate 46 is energized and works, causing the action layer 3 to vibrate through the transmission plate 45. During the vibration, the action layer 3 acts on the cathode gas diffusion layer 14, causing slight changes in the internal fiber pores 143 and acting on the ice layer. Since the ice layer formed by the water film is thin, under the action of force, some of the ice layer breaks or the gap between the ice layer and the fiber pores 143 increases, and the water film can flow out. At this time, in conjunction with the start-up of the fuel cell, the internal ice layer can be quickly broken and melted to avoid a cold start.

[0034] Implementation Force 3: The pressure detection unit 5 includes a cavity 51 disposed inside the pressure-resistant frame 2, and the cavity 51 is located near one of the corners of the pressure-resistant frame 2. Further explanation: since every point on the membrane electrode body 1 can be affected when the assembly machine applies pressure, only a single point needs to be detected. Adding multiple detection points would reduce the structural strength of the pressure-resistant frame 2. A trapezoidal block 1 52 is disposed inside the cavity 51, and a trapezoidal block 2 53 is disposed inside the cavity 51 for sliding connection with trapezoidal block 1 52. A through-post 54 is installed on trapezoidal block 1 52, and the end of the through-post 54 penetrates the inner wall of the cavity 51 and extends to the top of the pressure-resistant frame 2. A force-bearing panel 55 is installed at the end of the through-post 54. The through-post 54 is slidably connected to the inner wall of the top of the pressure-resistant frame 2, and a useful... In the initial state, trapezoidal block 52 and trapezoidal block 53 are in contact with each other in the circular groove 501 that is slidably connected to the force-bearing panel 55, and the force-bearing panel 55 is located above the circular groove 501. A magnetic block 56 is installed at the end of trapezoidal block 53, and a thick magnet 57 is fixedly installed on the inner wall of the cavity 51 to generate an attractive force on the magnetic block 56. The thick magnet 57 generates a certain attraction force on the magnetic block 56, and the thick magnet 57 is a strong magnet with a strong attraction force. Trapezoidal block 53 is slidably connected to the inner wall of the cavity 51. A connecting post 58 is installed at the end of trapezoidal block 53, and a circular hole 59 is provided on the side wall of the compression frame 2. The end of the connecting post 58 is located in the circular hole 59 and a detection panel 50 is installed thereon. The detection panel 50 is also located in the circular hole 59.

[0035] Specifically, during the assembly process, an electrode plate (which generates a signal or current upon contact) is installed at the circular hole 59, and the electrode plate is electrically connected to the control system on the assembly machine. During the assembly process, the operator uses the assembly machine to assemble the membrane electrode body 1. The assembly machine acts on the pressure-resistant frame 2 through the bipolar plate, which first acts on the force-bearing panel 55. The force-bearing panel 55 descends, and during the descent, the trapezoidal block 52 acts on the trapezoidal block 53 through the through column 54, causing it to move in an orienting motion. The magnetic block 56 on the trapezoidal block 53 gradually moves away from the thick magnet 57, and under the action of the connecting column 58, the detection panel 50 gradually approaches the electrode plate. Since the electrode plate is an existing structure, this invention does not describe it in detail. When the assembly pressure reaches the limit value, the detection panel 50 touches and acts on the electrode plate, so that the electrode plate sends information to the assembly machine through electrical signal transmission, and the assembly machine stops working. Thus, through the structural design of this invention, the assembly pressure can be effectively controlled, avoiding assembly failure due to excessive or insufficient pressure, improving both assembly efficiency and assembly quality.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-performance fuel cell membrane electrode assembly (MEA), comprising a MEA body (1), wherein the MEA body (1) is composed of a proton exchange membrane (11), a cathode catalyst layer (12) and an anode catalyst layer (13) disposed on both sides of the proton exchange membrane (11), and a cathode gas diffusion layer (14) and an anode gas diffusion layer (15) disposed on one side of the cathode catalyst layer (12) and the anode catalyst layer (13), characterized in that: A pressure-resistant frame (2) is installed on one side of the proton exchange membrane (11), and an active layer (3) is provided inside the pressure-resistant frame (2). The cathode catalyst layer (12) and the cathode gas diffusion layer (14) are located inside the active layer (3), and the active layer (3) also includes: The action unit (4) is provided on the pressure-resistant frame (2), and the action unit (4) is used to clear the ice pores (143) in the cathode gas diffusion layer (14) through the action layer (3); and the pressure detection unit (5) is provided inside the pressure-resistant frame (2), and the pressure detection unit (5) is used to detect the installation pressure when the membrane electrode body (1) is installed; the action unit (4) includes a cavity (41) provided inside the pressure-resistant frame (2), and an electric heating wire (42) is provided inside the cavity (41), and heat conversion channels (43) for connecting with the two side walls of the action layer (3) are installed on the inner walls of both sides of the pressure-resistant frame (2).

2. A high-performance fuel cell membrane electrode according to any one of claims 1, characterized in that: The action unit (4) includes a connecting frame (44) disposed on the inner walls of both sides of the compression frame (2), wherein a transmission plate (45) is installed on both sides of the action layer (3), and the end of the transmission plate (45) is located inside the connecting frame (44), and piezoelectric vibrating plates (46) are installed on the inner walls of the top and bottom of the connecting frame (44).

3. The high-performance fuel cell membrane electrode according to claim 1, characterized in that: The cathode gas diffusion layer (14) is composed of multiple A regions (141) and B regions (142), wherein the multiple A regions (141) and B regions (142) are equidistantly staggered on the cathode gas diffusion layer (14), and the A regions (141) and B regions (142) are respectively a hydrophobic layer and a hydrophilic layer.

4. The high-performance fuel cell membrane electrode according to claim 3, characterized in that: Both region A (141) and region B (142) are composed of multiple pores (143), and the contact angle θc of region A (141) is in the range of 90°-150°, while the contact angle θc of region B (142) is in the range of 10°-90°.

5. A high-performance fuel cell membrane electrode according to claim 4, characterized in that: The size of the pores (143) in region A (141) is smaller than the size of the pores (143) in region B (142).

6. The high-performance fuel cell membrane electrode according to claim 1, characterized in that: The pressure detection unit (5) includes a cavity (51) disposed inside the pressure-resistant frame (2), and the cavity (51) is located near one of the corners of the pressure-resistant frame (2). A trapezoidal block one (52) is disposed inside the cavity (51), and a trapezoidal block two (53) is disposed inside the cavity (51) for sliding connection with the trapezoidal block one (52). A through column (54) is installed on the trapezoidal block one (52), and the end of the through column (54) penetrates the inner wall of the cavity (51) and extends to the top of the pressure-resistant frame (2). A force-bearing panel (55) is installed at the end of the through column (54). A magnetic block (56) is installed at the end of the trapezoidal block two (53), and a thick magnet (57) for generating an attractive force on the magnetic block (56) is fixedly installed on the inner wall of the cavity (51). The trapezoidal block two (53) is slidably connected to the inner wall of the cavity (51).

7. A high-performance fuel cell membrane electrode according to claim 6, characterized in that: The trapezoidal block 2 (53) is equipped with a connecting column (58) at its end, and a circular hole (59) is provided on the side wall of the compression frame (2). The end of the connecting column (58) is located in the circular hole (59) and is equipped with a detection panel (50). The top of the compression frame (2) is provided with a circular groove (501) for sliding connection with the force-bearing panel (55).

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