Flow field plate device of proton exchange membrane electrolytic cell

Abstract

The invention discloses a proton exchange membrane electrolyzer flow field plate device, which belongs to the technical field of proton exchange membrane electrolyzed water, and comprises an anode flow field plate and a cathode flow field plate, the anode flow field plate is the same as the cathode flow field plate, one side plate surface of the anode flow field plate is provided with a plurality of parallel linear flow channels, and the other side plate surface of the anode flow field plate is provided with a plurality of parallel linear flow channels. Through holes perpendicular to the plate surface of the anode flow field plate are formed in the two ends of each linear flow channel; every two adjacent linear runners are separated by a ridge, and the top of the cross section of each ridge is in an arch shape. According to the invention, the uniformity of current density and the utilization of a catalyst are improved, and the linear flow channel is simple in structure and easy to process. The design of the through holes at the two ends improves gas utilization rate and flow velocity, and water generated by reaction is easy to discharge. The defects that the snake-shaped flow channel is high in airflow speed, long in path, large in pressure loss and easy to cause that the electrolytic cell cannot work are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of proton exchange membrane water electrolysis, and particularly relates to a proton exchange membrane electrolyzer flow field plate device. Background Art

[0002] Currently, proton exchange membrane electrolyzers (PEM electrolyzers) are assembled from a proton exchange membrane, catalyst, gas diffusion layer, and flow field plate. The flow field plate serves as a support for the membrane structure and isolates the gas, so its drainage and exhaust properties, thermal dispersion, and ability to withstand clamping forces must be considered.

[0003] Current PEM electrolyzers mainly use metal flow field plates, most commonly regular serpentine flow fields, which have poor fluidity for gas and liquid water. In addition, the serpentine flow channel has high air flow velocity, long path, and large pressure loss, which can easily cause the electrolyzer to malfunction. In addition, the cathode flow field and anode flow field plates need to be designed separately, and the flow field plates have poor adaptability. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments.

[0005] The present invention solves the shortcomings of the prior art flow field plate serpentine flow channel, such as high air flow velocity, long path, large pressure loss, which easily causes the electrolyzer to fail to work, and the need to design the cathode flow field and anode flow field plates separately, and provides a proton exchange membrane electrolyzer flow field plate device.

[0006] The present invention provides a proton exchange membrane electrolyzer flow field plate device, which is characterized in that it includes an anode flow field plate and a cathode flow field plate, the anode flow field plate is identical to the cathode flow field plate, a plurality of mutually parallel linear flow channels are provided on one side surface of the anode flow field plate, and through holes perpendicular to the plate surface of the anode flow field plate are provided at both ends of each linear flow channel; every two adjacent linear flow channels are separated by a ridge, and the top of the cross section of the ridge is arched.

[0007] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention, the bottom of the cross section of the ridge is square.

[0008] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention, the heights of each two ridges are different.

[0009] As a preferred embodiment of the proton exchange membrane electrolyzer flow field plate device of the present invention, every four adjacent ridges are grouped together, and the groups are arranged regularly. The height arrangement pattern of the ridges is as follows: the first ridge has the largest height, the second ridge is lower than the first ridge, the third ridge is lower than the second ridge, and the fourth ridge is the same height as the second ridge.

[0010] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention, the ratio of the length to the width of the linear flow channel is 50 to 100:1.

[0011] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention, the ratio of the length of the linear flow channel to the aperture of the through hole is 50 to 100:1.

[0012] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention, the width of each linear flow channel is equal to the width of the ridge.

[0013] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention, the distance between every two ridges is equal.

[0014] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention, a groove is provided on the periphery of the flow channel area of ​​the anode flow field plate.

[0015] As a preferred solution of the proton exchange membrane electrolyzer flow field plate device of the present invention: the material of the anode flow field plate and the cathode flow field plate includes platinum-plated aluminum plate.

[0016] The present invention improves current density uniformity and catalyst utilization, while also simplifying the linear flow channel structure and making it easy to process. The through-hole design at both ends improves gas utilization, increases flow rate, and facilitates the discharge of water generated by the reaction. This overcomes the shortcomings of serpentine flow channels, which suffer from high gas velocity, long paths, and high pressure drop, which can easily cause electrolytic cell inoperability.

[0017] The present invention enables the water medium to form a turbulent effect during the flow process, increases the contact area and contact time between the water medium and the reactants inside the electrolyzer, effectively avoids the rapid loss of the water medium, and enables it to fully react chemically with other reactants in the proton exchange membrane electrolyzer, significantly improves the overall performance of the electrolyzer, and extends the durability of the flow field.

[0018] The top of the cross-section of the ridge of the present invention is arched, which has significant advantages in improving the performance of the electrolyzer and protecting key components. When the proton exchange membrane electrolyzer is assembled, the arched top forms a uniform contact pressure distribution with the membrane electrode surface, avoiding the situation where the traditional right-angle top is prone to forming local excessive or insufficient pressure, and at the same time effectively preventing the gas diffusion layer from falling into the flow field. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, wherein:

[0020] Figure 1 This is the overall picture of the anode flow field plate.

[0021] Figure 2 Schematic diagram of the cross section of the anode flow field plate.

[0022] Figure 3 The performance of the membrane electrode assembly under the flow field plate of Example 1, Comparative Example 1 or Comparative Example 2 was tested.

[0023] Figure 4 This is the high-frequency impedance test result diagram.

[0024] In the figure, 1 is the flow channel, 2 is the through hole, 3 is the ridge, 4 is the groove, L is the length of the flow channel, B is the width of the flow channel, W is the width of the ridge, and H is the height of the ridge. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0026] The present invention provides a proton exchange membrane electrolyzer flow field plate device, comprising an anode flow field plate and a cathode flow field plate. The anode flow field plate is identical to the cathode flow field plate. A plurality of mutually parallel linear flow channels are provided on one side surface of the anode flow field plate. Through holes perpendicular to the anode flow field plate surface are provided at both ends of each linear flow channel. Every two adjacent linear flow channels are separated by a ridge, and the top of the cross section of the ridge is arched.

[0027] Preferably, the cross-section of the ridge is square at the bottom.

[0028] Preferably, the heights of each two ridges are different.

[0029] Furthermore, every four adjacent ridges are grouped together, and the groups are arranged regularly. The ridge height arrangement pattern is: the first ridge is the highest, the second ridge is lower than the first ridge, the third ridge is lower than the second ridge, and the fourth ridge is the same height as the second ridge.

[0030] Preferably, the ratio of the length to the width of the linear flow channel is 50-100:1.

[0031] Preferably, the ratio of the length of the linear flow channel to the aperture of the through hole is 50-100:1.

[0032] Preferably, the width of each linear flow channel is equal to the width of the ridge, and the distance between every two ridges is equal.

[0033] The material of the flow field plate includes a platinum-plated aluminum plate. Preferably, the aluminum plate has a thickness of 5 mm to 15 mm, and a coating thickness of the platinum-plated aluminum plate is 50 to 200 nm, preferably 100 nm.

[0034] Preferably, a groove is provided on the periphery of the flow channel region of the anode flow field plate.

[0035] In the present invention, the design of the mutually parallel linear flow channels and the through-holes at both ends of the flow channels is shorter than that of the traditional serpentine flow channels, and the pressure loss at the inlet and outlet is small, which is conducive to the uniform distribution of gas and cooling water, improving the uniformity of current density and the utilization of catalyst. At the same time, the linear flow channel has a simple structure and is easy to process. The design of the through-holes at both ends improves gas utilization, increases flow rate, and facilitates the discharge of water generated by the reaction. This overcomes the shortcomings of the serpentine flow channel, such as high air flow velocity, long path, large pressure loss, and easy to cause the electrolyzer to fail to work.

[0036] Among them, every two adjacent straight flow channels are separated by a ridge, so that the gas can be transmitted in the flow field with the shortest path and less resistance. At the same time, the non-connected flow channel design avoids the disordered mixing and eddy current phenomenon of the gas in the flow field, so that the gas can be evenly distributed to the reaction area of ​​the electrolyzer according to the preset path. In actual application, the design of the straight flow channel and the through holes at both ends of the flow channel significantly improves the gas diffusion effect. Through real-time monitoring of different areas by gas concentration detection equipment, it is found that this design achieves highly uniform diffusion of gas inside the electrolyzer, providing a good gas environment for efficient reaction of the electrolyzer.

[0037] In the traditional electrolytic cell structure, the water medium flows at a high speed inside the electrolytic cell, and it is easy to be washed away before fully participating in the reaction, resulting in insufficient reaction and the inability to fully exert the performance of the electrolytic cell. The height arrangement rule of every two ridges of the present invention is: the first ridge has the largest height, the second ridge is lower than the first ridge, the third ridge is lower than the second ridge, and the fourth ridge is the same height as the second ridge. Every four adjacent ridges are grouped as a group, and each group is arranged regularly. The principle of fluid mechanics is cleverly utilized. When the water medium enters the inverted triangle-like area formed by the top of the second, third and fourth ridges, due to the height difference of the ridges, the flow rate of the water medium will gradually decrease and the residence time will be extended. At the same time, the special structure of the inverted triangle makes the water medium form a turbulent effect during the flow process, increasing the contact area and contact time between the water medium and the reactants inside the electrolytic cell, effectively avoiding the rapid loss of the water medium, so that it can fully react chemically with other reactants in the proton exchange membrane electrolyzer, significantly improving the overall performance of the electrolytic cell, and extending the durability of the flow field.

[0038] The top of the ridge's cross-section is arched, offering significant advantages in improving electrolyzer performance and protecting key components. Once the PEM electrolyzer is assembled, the arched top forms a uniform contact pressure distribution with the membrane electrode surface, avoiding the localized excessive or insufficient pressure often seen with conventional right-angled tops. It also effectively prevents the gas diffusion layer from becoming trapped in the flow field. During electrolyzer operation, conventional flow field structures, with their sharp corners, can easily cause the gas diffusion layer to deform under pressure or even become trapped within the flow field, thereby affecting gas transport and PEM electrolyzer performance. The arched surface, however, provides excellent support and protection for the gas diffusion layer, reducing the risk of component deformation and damage and effectively extending the PEM electrolyzer's service life.

[0039] The grooves around the flow channel area ensure a tight fit between the flow field plate and the gas diffusion layer during assembly of the proton exchange membrane electrolyzer, greatly reducing the risk of cross-gas transmission between different gas chambers. This ensures that the components are positioned quickly and accurately during installation, effectively avoiding positional movement due to installation deviation or applied force, and providing reliable protection for the stable operation of the electrolyzer.

[0040] During testing, the proton exchange membrane electrolyzer was assembled in the following order: cathode end plate, cathode insulator plate, cathode flow field plate, membrane electrode, anode flow field plate, anode insulator plate, and anode end plate. The cathode and anode flow field plates were identical and tightened with M6 bolts and nuts. Circulating water entered through the anode flow field plate. After assembly, the cells were tested using an electrochemical workstation (DH-7007). The assembled membrane electrode was subjected to IV performance testing: each linear flow channel of the flow field plate was 50 mm long and 0.5 mm wide. The ridges were 0.5 mm wide, with the first ridge height being 0.5 mm, the second ridge height being 0.45 mm, and the third ridge height being 0.4 mm. The active area of ​​the flow field region was 5 cm x 5 cm, and the through-hole radius at each end of the linear flow channel was 0.25 mm. A catalyst-coated membrane (CCM) was assembled between a 0.4 mm thick titanium felt at the anode and a 0.24 mm thick gas diffusion layer (GDL) at the cathode, and two polytetrafluoroethylene gaskets to form a membrane electrode assembly (MEA). The effective electrode area was 25 cm 2 The PEM thickness is 80 μm. The iridium loading of the anode CL is 1.0 mglr / cm 2 , the platinum loading of cathode CL is 0.4 mgPt / cm 2 The O-ring seal is used, the diameter of the O-ring is 0.2mm, the hardware is tightened with a torque of 8N·m, and the flow rate of circulating water at 60℃ and 100mL / min is 0.5A / cm 2 -1A / cm 2-1.5A / cm 2 -2A / cm 2 After 10 min activation, the test step was set to 0.5 A / cm at 60 °C and 100 mL / min circulating water flow. 2 Perform the test and record 0 A / cm 2 -1A / cm 2 -2A / cm 2 -3A / cm 2 The corresponding voltage data were tested on a proton exchange membrane water electrolysis test bench. Figure 3 As shown. Figure 3 It can be seen that the flow field plate of Example 1 has higher energy conversion efficiency, more efficient mass transfer process and less energy loss, thereby achieving a lower voltage at the same current density.

[0041] High Frequency Resistance (HFR) testing is used to monitor changes in water content. When the hydration capacity of the proton exchange membrane decreases, the HFR value increases, indicating that the membrane is drying out, indicating that the adhesion of the membrane electrode components in the proton exchange membrane electrolyzer test is reduced.

[0042] Connect the electrochemical workstation to the cathode and anode of the single cell, select EIS (electrochemical impedance spectroscopy) mode, and set the frequency to 0.1 to 10 5 HZ, high frequency impedance test of single cells under different electrical densities is performed at the test value of 15~25mQ impedance value.

[0043] At a current density of 0.5 A / cm 2 and 3.0A / cm 2 Under the conditions of , individual overpotential contributions (including HFR and kinetics) were analyzed for PEM water electrolysis cells with different flow field types. Although the HFR trend remains consistent across the overpotential range, kinetic losses dominate at lower current densities, while ohmic losses become increasingly important at higher current densities, while HFR resistance decreases relatively.

[0044] Comparative Example 1:

[0045] A commercially available cathode flow field plate with a three-snake flow channel is used, and the anode flow field plate adopts a single-snake flow channel. The flow channel width, depth and ridge width parameters of the anode flow field plate and the cathode flow field plate are consistent, with a flow channel depth of 0.5 mm and a ridge width of 1 mm. The active area of ​​the flow field plate is 5 cm*5 cm, and the test conditions are the same as in Example 1.

[0046] Comparative Example 2:

[0047] A commercially available cathode flow field plate was used, the flow channel was a single serpentine type, the anode flow field plate was a lattice type with a length and width of 2mm*2mm, the flow channel depth was 1mm, the spacing between each two lattice flow channels was 2mm, the active area of ​​the flow field plate was 5cm*5cm, and the test conditions were the same as those in Example 1.

[0048] from Figure 4 It can be seen that with the current density (0-4.0A / cm 2 ) increases, the HFR of Example 1 and Comparative Example 2 quickly tends to be stable, reflecting that the ohmic loss of the PEM electrolyzer enters a relatively stable stage after the current density is increased; however, the ohmic resistance of Comparative Example 1 increases abnormally at high current density, and the HFR increases sharply.

[0049] The H FR value of Example 1 is the lowest and stable (about 60 mΩ·cm 2 ), indicating that the ohmic loss in its flow field design is minimal, and the performance in the full current density range (especially high current) is more reliable. The initial HFR of Comparative Example 2 is higher. Although it decreases with the increase of current density, it is still higher than that of Example 1 as a whole, indicating that the initialization ohmic loss of Comparative Example 2 is greater, and the contact resistance between the flow field and the membrane electrode assembly is larger. Comparative Example 1 is at low / medium current density (0-3.5A / cm 2 )H FR is stable, but the ohmic loss increases abnormally at high current, and the energy efficiency drops sharply, indicating that the high current stability of Comparative Example 1 is poor, and there may be poor contact at the material structure interface, and the risk of failure under high load.

[0050] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A proton exchange membrane electrolyzer flow field plate device, characterized in that: It includes an anode flow field plate and a cathode flow field plate. The anode flow field plate is the same as the cathode flow field plate. A plurality of parallel linear flow channels are provided on one side of the anode flow field plate. Through holes perpendicular to the anode flow field plate surface are provided at both ends of each linear flow channel. Every two adjacent linear flow channels are separated by a ridge, and the top of the cross section of the ridge is arched.

2. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1, characterized in that: The cross-section of the ridge is square at the bottom.

3. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1 or 2, characterized in that: The height of each two ridges is different.

4. The flow field plate device for a proton exchange membrane electrolyzer according to claim 3, characterized in that: Every four adjacent ridges form a group, and each group is arranged regularly. The height arrangement pattern of the ridges is: the first ridge is the highest, the second ridge is lower than the first ridge, the third ridge is lower than the second ridge, and the fourth ridge is the same height as the second ridge.

5. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1 or 2, characterized in that: The ratio of the length to the width of the straight flow channel is 50 to 100:

1.

6. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1 or 2, characterized in that: The ratio of the length of the linear flow channel to the aperture of the through hole is 50 to 100:

1.

7. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1 or 2, characterized in that: The width of each linear flow channel is equal to the width of the ridge.

8. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1 or 2, characterized in that: The distance between each two ridges is equal.

9. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1 or 2, characterized in that: Grooves are arranged on the periphery of the flow channel area of ​​the anode flow field plate.

10. The flow field plate device for a proton exchange membrane electrolyzer according to claim 1 or 2, characterized in that: The materials of the anode flow field plate and the cathode flow field plate include platinum-plated aluminum plates.

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