A composite flow field assembly for an alkaline water electrolyzer

Abstract

This invention relates to a composite flow field assembly for an alkaline water electrolyzer, comprising a diaphragm, an anode and a cathode respectively disposed on both sides of the diaphragm, electrode plates disposed on the sides of the anode and cathode, an electrode frame matching the electrode plates, and an outlet and an inlet disposed on the electrode frame; the electrode plates have hemispherical protrusions and hemispherical depressions in the area near the inlet, and nickel mesh structures in the remaining positions. Compared with the prior art, this invention can achieve fluid dispersion of the nickel mesh flow field near the inlet in a simple manner, promoting uniform distribution of fluid in the flow field, thus improving the working stability of the electrolyzer. At the same time, the high specific surface area structure of the nickel mesh can also improve electrolysis efficiency, achieving higher electrolytic reaction activity. That is, it combines the advantages of both the nipple-shaped flow field and the nickel mesh flow field, resulting in better economic benefits and higher practical value.

Description

Technical Field

[0001] This invention relates to the field of electrolytic hydrogen production technology, and in particular to a composite flow field component for alkaline water electrolyzers. Background Technology

[0002] Hydrogen energy, as a clean, efficient, and sustainable energy source, will play a vital role in the future global energy system. Therefore, utilizing renewable electricity for water electrolysis to produce hydrogen is an inevitable requirement in line with my country's energy development trends. Consequently, with the increasing demand for renewable energy, the need for large-scale, high-purity hydrogen production is also growing stronger.

[0003] Alkaline electrolysis for hydrogen production is the most widely used water electrolysis technology. Also known as alkaline aqueous solution electrolysis for hydrogen production, it uses a strong alkali as the electrolyte and a porous membrane. This technology was the first water electrolysis technology discovered and applied, with over 100 years of industrial application history, and is of great significance for achieving my country's "dual carbon goals."

[0004] In commercially used alkaline water electrolyzers, a nickel mesh is typically used on the main electrode plate to form a flow field with the electrodes, replacing the traditional convex flow field. This flow field increases the contact between the electrodes and the electrolyte, reduces ohmic resistance, and further increases the maximum current density of the electrolyzer. However, at the inlet of the alkaline solution, the nickel mesh flow field does not have a significant flow-blocking effect, and its dispersing effect on the fluid still needs improvement.

[0005] Currently, there is limited research on novel nickel mesh flow fields, and no related patents exist; relevant patents are still concentrated on nipple-shaped flow fields. Chinese invention CN115652352 A discloses a modified nipple-shaped flow field, which modifies the traditional nipple flow field by creating a wave-shaped flow channel made of woven or printed mesh, partially reducing flow resistance. Chinese invention CN113818038A discloses an axially non-equidistant corrugated plate electrode with positive and negative protruding nipple structures on the electrode sheet. The spacing between adjacent nipple structures gradually increases from the central axis to the outside, resulting in a more uniform electrolyte distribution in the flow field, with the overall flow velocity approaching the fluid velocity near the central axis. It can be seen that the advantage of the traditional nipple-shaped flow field lies in its better dispersion effect on the fluid; however, compared to the nickel mesh flow field, the nipple-shaped flow field is more complex to manufacture, has higher costs, and lower efficiency.

[0006] Therefore, there is an urgent need to design a flow field that optimizes the flow field structure while maintaining high electrolytic reaction activity, that is, to combine the advantages of both the nipple flow field and the nickel mesh flow field. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite flow field component for alkaline water electrolyzers. This component can achieve fluid dispersion near the inlet of the nickel mesh flow field in a simple way, promoting uniform distribution of the fluid in the flow field. Therefore, it can improve the working stability of the electrolyzer. At the same time, the high specific surface area structure of the nickel mesh can also improve the electrolysis efficiency and achieve higher electrolysis reaction activity. That is, it combines the advantages of both the nipple flow field and the nickel mesh flow field, resulting in good economic benefits and high practical value.

[0008] The objective of this invention can be achieved through the following technical solutions: The present invention provides a composite flow field assembly for an alkaline water electrolyzer, comprising a diaphragm, an anode and a cathode respectively disposed on both sides of the diaphragm, an electrode plate disposed on the sides of the anode and the cathode, an electrode frame matching the electrode plate, an outlet, and an inlet. The electrode plate has a hemispherical protrusion and a hemispherical depression in the area near the liquid inlet, and a nickel mesh structure in the remaining positions.

[0009] Furthermore, the structure that needs to be described in this technical solution compared to conventional electrolytic bipolar plates is as follows: Liquid outlet: The outlet for alkaline solution, used to simplify the flow field, including radial outlet channels for alkaline solution outflow and gas-liquid channels, etc.

[0010] Liquid inlet: Alkali inlet, used to simplify the flow field, including radial inlet channels for alkali inflow and alkali channels, etc.

[0011] Nickel mesh structure: Part of the electrode plate, forming the flow field boundary with the other electrode plate. Nickel mesh structure is less expensive while increasing contact points, reducing ohmic resistance, and thus improving electrolysis efficiency.

[0012] Hemispherical protrusion structure: Together with the hemispherical depression structure, it serves as part of the electrode plate, dispersing the electrolyte introduced from the inlet.

[0013] Hemispherical concave structure: Together with the hemispherical convex structure, it serves as part of the electrode plate, dispersing the electrolyte introduced from the inlet.

[0014] Furthermore, the bottom of the electrode frame is provided with an alkaline solution channel for liquid inlet, and the top of the electrode frame is provided with a gas-liquid channel for liquid outlet.

[0015] Furthermore, the diameter of the hemispherical protrusion structure is 15 mm; The diameter of the hemispherical recessed structure is 15 mm.

[0016] Furthermore, radial perforated channels are provided between the electrode plate and the alkali solution channel, and between the electrode plate and the gas-liquid channel.

[0017] Furthermore, after the alkali solution enters the inner flow field of the electrode plate through the inlet, the alkali solution is forced to flow around the hemispherical protrusion structure and the hemispherical depression structure, forming a certain vortex, which makes the overall flow more turbulent, thereby achieving the initial dispersion of the alkali solution. After the initial dispersion of the alkali solution, the alkali solution enters the corresponding area of ​​the nickel mesh structure, and finally flows out from the radial hole channel and converges and flows out in the gas-liquid channel.

[0018] Furthermore, the electrode plate is welded to the electrode frame; A gasket is provided between the pole frame and the diaphragm.

[0019] Furthermore, the nickel mesh structure has a mesh count between 0.3 mesh and 400 mesh, a nickel purity of ≥99.6%, and a pore size between 0.02 mm and 24.0 mm.

[0020] In one embodiment of the present invention, the hemispherical protrusion structure and the hemispherical recess structure are arranged in a square staggered pattern, and only one liquid inlet is provided at the bottom of the flow field.

[0021] In one embodiment of the present invention, the hemispherical protrusion structure and the hemispherical depression structure are arranged in a square sequence, and only one liquid inlet is provided at the bottom of the flow field.

[0022] In one embodiment of the present invention, the hemispherical protrusion structure and the hemispherical depression structure are arranged in a square staggered pattern, and two liquid inlets are provided at the bottom of the flow field.

[0023] Compared with the prior art, the present invention has the following technical advantages: (1) The component structure in this technical solution is highly feasible, and the innovative flow field structure design with the characteristics of this invention only requires updating the electrode process. At the same time, both the hemispherical concave-convex structure and the related processes of nickel mesh can be mass-produced through automated processing, thus having great practical value.

[0024] (2) The structure of this technical solution optimizes the flow of alkaline solution. The hemispherical concave-convex structure can disperse the alkaline solution entering the flow field, promote the uniform distribution of alkaline solution in the flow field, avoid the phenomenon of uneven flow field distribution, and reduce the impact on performance. Attached Figure Description

[0025] Figure 1 This is a structural diagram of the composite flow field component for an alkaline water electrolyzer according to the present invention; Figure 2 This is one embodiment of the present invention. Figure 3 This is a schematic diagram of the corresponding flow field effect.

[0026] Figure 4 This is one embodiment of the present invention. Figure 5This is a schematic diagram of the corresponding flow field effect.

[0027] Figure 6 This is one embodiment of the present invention. Figure 7 This is a schematic diagram of the corresponding flow field effect.

[0028] In the figure: 1 is the electrode frame, 2 is the radial hole channel, 3 is the gasket, 4 is the anode, 5 is the diaphragm, 6 is the gas-liquid channel, 7 is the electrode plate, 8 is the cathode, 9 is the alkali channel, 10 is the nickel mesh structure, 11 is the hemispherical protrusion structure, 12 is the liquid inlet, 13 is the hemispherical recess structure, and 14 is the liquid outlet. Detailed Implementation

[0029] According to the present invention, a novel composite flow field component for alkaline water electrolyzers can be designed. The design provided by this invention has a simple structure, is easy to manufacture on a large industrial scale, and can be modified based on a nickel mesh flow field by incorporating a nipple-like structure at the inlet. It can be easily assembled with electrodes, and the flow field near the inlet can be easily dispersed, promoting uniform fluid distribution and thus improving the operational stability of the electrolyzer. Furthermore, the high specific surface area of ​​the nickel mesh can also improve electrolysis efficiency, resulting in good economic benefits and high practical value.

[0030] The composite flow field structure that makes this invention distinctive consists of an anode, a diaphragm, a gas-liquid flow channel, an electrode plate, a cathode, and an alkaline flow channel. By setting a hemispherical concave-convex structure below the electrode plate, the fluid entering the electrolysis region divided by the electrode plate is quickly dispersed into various directions of the circular cross-section of the electrolysis region, thereby fully developing the flow, ensuring the uniform distribution of the fluid in the flow field, and improving the stability of the electrolysis operation.

[0031] According to the present invention, by setting the above-mentioned flow field scheme in the electrolytic cell, a relatively uniform fluid will exist throughout the flow field. When the alkali solution enters the flow field, the hemispherical uneven structure at the flow field inlet forces the alkali solution to flow around the hemispherical uneven structure, forming a certain vortex, making the overall flow more turbulent, and the liquid is easier to disperse. After initial dispersion, the fluid enters the nickel mesh structure region, where the fluid can quickly traverse the entire flow field, ensuring smooth flow.

[0032] like Figure 1 As shown, this invention controls the properties of the flow field through an innovative electrode design. Gas-liquid channels for hydrogen and oxygen flow, an alkali solution channel, and radial perforated channels connecting to the electrolysis unit are formed on the electrode frame. The alkali solution flows into the electrode through the radial perforated channels and is evenly dispersed throughout the flow field by the hemispherical protrusions and depressions of the electrode. After passing through the flow field formed by the nickel mesh structure, it finally flows out from the radial perforated channels and converges in the gas-liquid channels.

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0034] Example 1 Figure 1-3 This is an illustrative schematic diagram for the first embodiment of the present invention, showing an example of a simplified novel composite flow field. A composite flow field assembly for an alkaline water electrolyzer, characteristic of the present invention, includes an anode 4, a diaphragm 5, a gas-liquid flow channel 6, an electrode 7, a cathode 8, and an alkaline flow channel 9. A portion of the area below the electrode 7, where it connects to the inlet 12, is provided with a hemispherical protrusion structure 11 and a hemispherical recess structure 13. The remaining structure, including the portion above connecting to the outlet 14, is entirely a nickel mesh structure 10. The hemispherical protrusion structure 11 and the hemispherical recess structure 13 below the electrode 7 are formed by mechanical stamping. The electrode plate can be made of metal materials such as nickel, titanium, and stainless steel. The remaining nickel mesh structure 10 has a mesh size between 0.3 mesh and 400 mesh, a nickel purity ≥99.6%, and a pore size between 0.02 mm and 24.0 mm.

[0035] The electrode plate 7 is surrounded by an electrode frame 1. The bottom of the electrode frame 1 is provided with an alkaline liquid flow channel 9 for liquid inlet and a gas-liquid flow channel 6 for liquid outlet. At the same time, a gasket 3 is installed between the electrode frame 1 and the diaphragm. There is a radial hole flow channel 2 connecting the electrode plate 7 with the alkaline liquid flow channel 9 and the gas-liquid flow channel 6. The electrode plate and the electrode frame are connected by welding.

[0036] In this example, potassium hydroxide or sodium hydroxide with a mass fraction of 25%-35% is used as the electrolyte. The alkaline solution enters the electrolytic cell through the alkaline solution channel 9, and then flows into the electrode plate 7 through the radial hole channel 2. After the fluid enters the flow field inside the electrode plate, the alkaline solution is forced to flow around the hemispherical protrusion structure 11 and the hemispherical depression structure 13, forming a certain vortex, making the overall flow more turbulent, and undergoing initial dispersion. After initial dispersion, the fluid enters the nickel mesh structure 10 region, and finally flows out from the radial hole channel 2 and converges and flows out through the gas-liquid channel 6. The diameter of the hemispherical protrusion structure is 15 mm, and the diameter of the hemispherical depression structure is 15 mm.

[0037] In this embodiment, such as Figure 2 As shown, the hemispherical protrusion structure 11 and the hemispherical recess structure 13 are arranged in a square staggered pattern. The hemispherical protrusion structure 11 and the hemispherical recess structure 13 are not adjacent in either the horizontal or vertical directions, and an inlet is only provided at the lowest point of the flow field. The effect achieved by this embodiment is as follows: Figure 3As shown, after the alkali solution enters the flow field, it is effectively dispersed by the staggered hemispherical protrusions 11 and hemispherical depressions 13, resulting in some vortex characteristics. It quickly diffuses to all directions of the nickel mesh flow field and then flows out from the outlet 14 along the nickel mesh flow field. The composite flow field effectively enhances the uniform distribution of the fluid in the flow field.

[0038] Example 2 Figure 1 , 4 -5 is an illustrative diagram for the second embodiment of the present invention, showing an example of a simplified novel composite flow field. A composite flow field for an alkaline water electrolyzer, characteristic of the present invention, includes an anode 4, a diaphragm 5, a gas-liquid flow channel 6, an electrode 7, a cathode 8, and an alkaline flow channel 9. A portion of the area below the electrode 7, where it connects to the inlet 12, is provided with a hemispherical protrusion structure 11 and a hemispherical recess structure 13. The remaining structure, including the portion above connecting to the outlet 14, is entirely a nickel mesh structure 10. The hemispherical protrusion structure 11 and the hemispherical recess structure 13 below the electrode 7 are formed by mechanical stamping, with a substrate of metallic materials such as nickel, titanium, and stainless steel. The remaining nickel mesh structure 10 has a mesh size between 0.3 mesh and 400 mesh, a nickel purity ≥99.6%, and a pore size between 0.02 mm and 24.0 mm. The electrode plate 7 is surrounded by an electrode frame 1. The bottom of the electrode frame 1 is provided with an alkaline liquid flow channel 9 for liquid inlet and a gas-liquid flow channel 6 for liquid outlet. At the same time, a gasket 3 is installed between the electrode frame 1 and the diaphragm. There is a radial hole flow channel 2 connecting the electrode plate 7 with the alkaline liquid flow channel 9 and the gas-liquid flow channel 6. The electrode plate and the electrode frame are connected by welding.

[0039] In this example, potassium hydroxide or sodium hydroxide with a mass fraction of 25%-35% is used as the electrolyte. The alkaline solution enters the electrolytic cell through the alkaline solution channel 9, and then flows into the electrode plate 7 through the radial hole channel 2. After the fluid enters the flow field inside the electrode plate, the alkaline solution is forced to flow around the hemispherical protrusion structure 11 and the hemispherical concave structure 13, forming a certain vortex, making the overall flow more turbulent, and undergoing initial dispersion. After initial dispersion, the fluid enters the nickel mesh structure 10 region, and finally flows out from the radial hole channel 2 and converges and flows out through the gas-liquid channel 6.

[0040] In this embodiment, such as Figure 4 As shown, the hemispherical protrusions 11 and hemispherical recesses 13 are arranged in a square sequence, while the hemispherical protrusions 11 and hemispherical recesses 13 are staggered in a horizontal arrangement. Only one liquid inlet is located at the very bottom of the flow field. The effect achieved by this embodiment is as follows: Figure 5As shown, after the alkaline solution enters the flow field, it is effectively dispersed by the staggered hemispherical protrusions 11 and hemispherical depressions 13. The sequential arrangement further enhances the dispersion effect on the fluid, but it will generate a large number of vortex motion areas in the hemispherical protrusion and depression regions, forming a large area of ​​low flow velocity region. The fluid will slowly diffuse in this region and then flow out from the outlet 14 along the nickel mesh flow field.

[0041] Example 3 Figure 1 , 6 -7 is an illustrative diagram for the third embodiment of the present invention, showing an example of a simplified novel composite flow field. A composite flow field for an alkaline water electrolyzer, characteristic of the present invention, includes an anode 4, a diaphragm 5, a gas-liquid flow channel 6, an electrode 7, a cathode 8, and an alkaline flow channel 9. A portion of the area below the electrode 7, where it connects to the inlet 12, is provided with a hemispherical protrusion structure 11 and a hemispherical recess structure 13. The remaining structure, including the portion above connecting to the outlet 14, is entirely a nickel mesh structure 10. The hemispherical protrusion structure 11 and the hemispherical recess structure 13 below the electrode 7 are formed by mechanical stamping, with a substrate of metallic materials such as nickel, titanium, and stainless steel. The remaining nickel mesh structure 10 has a mesh size between 0.3 mesh and 400 mesh, a nickel purity ≥99.6%, and a pore size between 0.02 mm and 24.0 mm. The electrode plate 7 is surrounded by an electrode frame 1. The bottom of the electrode frame 1 is provided with an alkaline liquid flow channel 9 for liquid inlet and a gas-liquid flow channel 6 for liquid outlet. At the same time, a gasket 3 is installed between the electrode frame 1 and the diaphragm. There is a radial hole flow channel 2 connecting the electrode plate 7 with the alkaline liquid flow channel 9 and the gas-liquid flow channel 6. The electrode plate and the electrode frame are connected by welding.

[0042] In this example, potassium hydroxide or sodium hydroxide with a mass fraction of 25%-35% is used as the electrolyte. The alkaline solution enters the electrolytic cell through the alkaline solution channel 9, and then flows into the electrode plate 7 through the radial hole channel 2. After the fluid enters the flow field inside the electrode plate, the alkaline solution is forced to flow around the hemispherical protrusion structure 11 and the hemispherical concave structure 13, forming a certain vortex, making the overall flow more turbulent, and undergoing initial dispersion. After initial dispersion, the fluid enters the nickel mesh structure 10 region, and finally flows out from the radial hole channel 2 and converges and flows out through the gas-liquid channel 6.

[0043] In this embodiment, such as Figure 6 As shown, the hemispherical protrusion structure 11 and the hemispherical recess structure 13 are arranged in a square staggered pattern. The hemispherical protrusion structure 11 and the hemispherical recess structure 13 are not adjacent in either the horizontal or vertical directions. Two liquid inlets are located at the lowest point of the flow field. The effect achieved by this embodiment is as follows: Figure 7As shown, after the alkali solution enters the flow field, it is effectively dispersed by the staggered hemispherical protrusions 11 and hemispherical depressions 13, resulting in some vortex characteristics. It quickly diffuses to all directions of the nickel mesh flow field. The dual inlets enhance the dispersion effect and increase the fluid velocity on both sides. Afterward, the fluid continues to flow out from the outlet 14 along the nickel mesh flow field, but a dead zone may be formed at the bottom of the flow field.

[0044] Those skilled in the art should understand that this invention is not limited to the above embodiments. Other spherical convex / concave structure designs, arrangements, and inlet designs should also be included within the scope of protection of this invention. The above embodiments only illustrate the principles of this invention. Any changes and improvements based on this invention without departing from its principles fall within the scope of the claimed patent.

[0045] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A composite flow field component for an alkaline water electrolyzer, characterized in that, It includes a diaphragm (5), an anode (4) and a cathode (8) respectively disposed on both sides of the diaphragm (5), an electrode plate (7) disposed on the side of the anode (4) and the cathode (8), an electrode frame (1) matching the electrode plate (7), an outlet (14), and an inlet (12). The electrode plate (7) is provided with a hemispherical protrusion structure (11) and a hemispherical recess structure (13) in the area near the liquid inlet (12), and a nickel mesh structure (10) is provided in the other positions. The bottom of the electrode frame (1) is provided with an alkaline liquid flow channel (9) for liquid inlet, and the top of the electrode frame (1) is provided with a gas-liquid flow channel (6) for liquid outlet. There are radial hole channels (2) connecting the electrode plate (7) and the alkaline liquid flow channel (9), and the electrode plate (7) and the gas-liquid flow channel (6). The electrode plate (7) is welded to the electrode frame (1), and a gasket (3) is provided between the electrode frame (1) and the diaphragm (5). After the alkaline solution enters the inner flow field of the electrode plate through the inlet (12), the alkaline solution is forced to flow around the hemispherical protrusion structure (11) and the hemispherical concave structure (13), forming a certain vortex, which makes the overall flow more turbulent, thereby achieving the initial dispersion of the alkaline solution. After the initial dispersion of the alkaline solution, the alkaline solution enters the corresponding area of ​​the nickel mesh structure (10), and finally flows out from the radial hole channel (2) and converges and flows out in the gas-liquid channel (6); Furthermore, the hemispherical protrusion structure (11) and the hemispherical recess structure (13) are arranged in a square staggered arrangement, and only one liquid inlet (12) is set at the bottom of the flow field. Alternatively, the hemispherical protrusion structure (11) and the hemispherical recess structure (13) are arranged in a square sequential arrangement, and only one liquid inlet (12) is set at the bottom of the flow field.

2. The composite flow field component for an alkaline water electrolyzer according to claim 1, characterized in that, The diameter of the hemispherical protrusion structure (11) is 15 mm; The diameter of the hemispherical recessed structure (13) is 15 mm.

3. The composite flow field component for an alkaline water electrolyzer according to claim 1, characterized in that, The nickel mesh structure (10) has a mesh size between 0.3 mesh and 400 mesh, a nickel purity of ≥99.6%, and a pore size between 0.02 mm and 24.0 mm.

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