A two-chamber electrolysis unit using high-performance electrode plates

Abstract

The invention discloses a double-chamber electrolysis unit adopting a high-performance electrode plate, wherein a flow channel area of ​​a cathode flow field at least comprises a cathode straight flow channel area having a plurality of straight flow channels and a curved flow channel area having a plurality of bent flow channels, wherein the cathode straight flow channel area is evenly arranged on both sides of the curved flow channel area; the length of the bent flow channel is 1.1-1.3 times the length of the straight flow channel; by extending the path length of the electrolyte passing through the bent flow channel, the pressure drop of the electrolyte flowing through the curved flow channel area is 1-2 times that of the pressure drop of the cathode straight flow channel area, and the overall pressure drop of the cathode flow field is also increased, so that the flow rate of hydrogen is reduced, and the excessively fast outflow of hydrogen in the cathode flow channel is avoided; the invention ensures that the electrolyte is evenly distributed in the flow channel, and by optimizing the layout of the flow channel area and adding the design of anode bent flow channel and anode flow channel truncation on the basis of the variable diameter flow channel, the working stability of the electrolysis unit is ensured, and the efficiency and stability of the electrolysis unit are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolyzing water, and particularly to a two-chamber electrolysis unit using high-performance electrode plates. Background Art

[0002] With the increasingly wide application of the alkaline anion exchange membrane (AEM) electrolysis water hydrogen production technology in hydrogen energy production, it is urgent to improve the performance of the AEM electrolysis unit. Among them, as one of the core components of the electrolysis unit, the innovative design and patent layout of the electrode plate play a key role in improving the performance of the electrolysis unit and reducing production costs. The AEM electrolysis unit has attracted wide attention due to its advantages such as simple operation and low dependence on precious metals. As an important component in the electrolysis unit, the electrode plate has multiple functions such as conducting current, separating gases, and providing flow channels. Therefore, the design of the electrode plate has a great impact on the overall performance of the electrolysis unit.

[0003] Patent CN118407075A discloses a bipolar plate and an electrolytic cell. The anode flow channel of the bipolar plate adopts a variable flow channel. By changing the local flow cross-sectional area of the anode flow field of the PEM electrolytic cell bipolar plate, the local flow channel flow resistance is adjusted, thereby promoting longitudinal mass transfer of the fluid, reducing the mass transfer polarization loss of the electrolytic cell, and improving the high current density electrolysis performance of the electrolytic cell.

[0004] There is still room for improvement in the stability of the electrolysis unit during operation and the control of the hydrogen evolution flow rate at the cathode in the above patent. In view of this, it is necessary to design an electrode plate with smaller voltage fluctuations and better stability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a two-chamber electrolysis unit using high-performance electrode plates in view of the deficiencies in the above-mentioned prior art.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A dual-chamber electrolysis unit using high-performance electrode plates. The dual-chamber electrolysis unit at least includes a cathode plate with a cathode flow field and an anode plate with an anode flow field. The cathode monoplate has a cathode flow field, the anode monoplate has an anode flow field, and the bipolar plate has a cathode flow field and an anode flow field. The cathode flow field includes a first electrolyte inlet, a first inlet distribution area, a first flow channel area, a first outlet distribution area, and a first electrolyte outlet arranged in sequence along the electrolyte flow direction. The flow channel area of the cathode flow field includes multiple flow channels for the electrolyte to pass through. The flow channel area of the cathode flow field at least includes a cathode linear flow channel area with multiple straight flow channels and a curved flow channel area with multiple bent flow channels. The cathode linear flow channel area is evenly arranged on both sides of the curved flow channel area; the length of the bent flow channel is 1.1 - 1.3 times the length of the straight flow channel; by means of including extending the path length of the electrolyte passing through the bent flow channel, the pressure drop of the electrolyte flowing through the curved flow channel area reaches a ratio of 1 - 2 times that of the cathode linear flow channel area, and at the same time, the overall pressure drop of the cathode flow field is also increased, so that the flow rate of hydrogen is reduced, and the hydrogen in the cathode flow channel is prevented from flowing out too fast;

[0007] The anode flow field includes a second electrolyte inlet, a second inlet distribution area, a second flow channel area, a second outlet distribution area, and a second electrolyte outlet arranged in sequence along the electrolyte flow direction. The second flow channel area includes multiple flow channels for the electrolyte to pass through. The second flow channel area at least includes an anode linear flow channel area with multiple straight flow channels and a truncated distribution type flow channel area with multiple multi-segment line type flow channels. The anode linear flow channel area is evenly arranged on both sides of the truncated distribution type flow channel area; each of the multi-segment line type flow channels is composed of two flow channel ridges with uniformly and symmetrically distributed multiple break points; the electrolyte flow directions of the anode linear flow channel area and the cathode linear flow channel area are perpendicular to each other.

[0008] Preferably, the bent flow channel is a wavy flow channel; the length of each break point on both flow channel ridges of the multi-segment line type flow channel is not greater than the width of the multi-segment line type flow channel.

[0009] Preferably, the area of the curved flow channel area accounts for 40% - 60% of the area of the first flow channel area.

[0010] Preferably, the flow channel width of the wavy flow channel decreases at its wave crest and / or wave trough.

[0011] Preferably, the flow channel width of the wavy flow channel at its wave crest and / or wave trough is not less than 70% of the width at the remaining flow channel positions.

[0012] Preferably, a convex platform with a height not greater than 1 / 3 of the height of the flow channel ridge is also provided in the multi-segment line type flow channel, and the convex platform is arranged between two symmetric flow channel ridges.

[0013] Preferably, the double-chamber electrolysis unit includes a left end plate, a left insulating gasket, a cathode monoplate, a first-chamber cathode insulating seal frame, a first-chamber membrane electrode, a first-chamber anode insulating seal frame, a bipolar plate, a second-chamber cathode insulating seal frame, a second-chamber membrane electrode, a second-chamber anode insulating seal frame, an anode monoplate, a right insulating gasket, and a right end plate arranged in sequence. Among them, the cathode monoplate has a cathode flow field, the anode monoplate has an anode flow field, and the bipolar plate has a cathode flow field and an anode flow field.

[0014] Preferably, the materials of the left end plate and the right end plate are stainless steel, titanium or nickel.

[0015] Preferably, the diffusion layer of the membrane electrode is made of a conductive porous material.

[0016] Preferably, the left insulating gasket, the first-chamber cathode insulating seal frame, the first-chamber anode insulating seal frame, the second-chamber cathode insulating seal frame, the second-chamber anode insulating seal frame, and the right insulating gasket are all made of insulating and corrosion-resistant materials, and the insulating and corrosion-resistant materials at least include materials such as PTFE, PP, PPS, silica gel or fluororubber.

[0017] The beneficial effects of the present invention are:

[0018] 1. This structure ensures uniform distribution of the electrolyte in the flow channels. Through innovative flow channel design and flow field distribution structure, the efficiency and stability of the electrolysis unit are improved; the bipolar plate structure has high-efficiency gas separation ability, good electrical conductivity and excellent corrosion resistance, effectively improving the energy utilization rate in the electrolytic hydrogen production process.

[0019] 2. Compared with other plates with variable flow channels, the present invention optimizes the layout of the flow channel area and adds the design of an anode curved flow channel and an anode flow channel truncation on the basis of the variable flow channel, ensuring the stability of the electrolysis unit during operation. The maximum fluctuation before optimization is 6.6 mV, and the maximum fluctuation of the test voltage of the electrolysis unit after optimization is reduced to about 3.6 mV. At the same time, the performance of the electrolysis unit is also improved. Under the same working conditions (1MKOH, 1A / cm²@60°C), the average cell voltage after optimization is reduced by about 100 mV. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of a double-chamber electrolysis unit using high-performance plates.

[0021] Figure 2 It is a schematic structural diagram of a cathode flow field.

[0022] Figure 3 For Figure 2 The partial enlarged view of area A in

[0023] Figure 4It is a schematic structural diagram of an anode flow field.

[0024] Figure 5 It is Figure 4 a partial enlarged view of region B in

[0025] Figure 6 a performance test comparison diagram between the optimized electrolysis cell of the present invention and a conventional electrolysis cell.

[0026] Explanation of reference numerals: left end plate 1, left insulating gasket 2, cathode single plate 3, first chamber cathode insulating seal frame 4, first chamber membrane electrode 5, first chamber anode insulating seal frame 6, bipolar plate 7, second chamber cathode insulating seal frame 8, second chamber membrane electrode 9, second chamber anode insulating seal frame 10, anode single plate 11, right insulating gasket 12 and right end plate 13, cathode flow field 100, anode flow field 200, first electrolyte inlet 110, first inlet distribution area 120, first flow channel area 130, first outlet distribution area 140, first electrolyte outlet 150, cathode straight flow channel area 160, curved flow channel area 170, bent flow channel 171, second electrolyte inlet 210, second inlet distribution area 220, second flow channel area 230, second outlet distribution area 240, second electrolyte outlet 250, anode straight flow channel area 260, truncated distribution type flow channel area 270, multi-segment line type flow channel 271, flow channel ridge 280, break point 281, boss 290. Specific embodiments

[0027] The following further elaborates on the present invention in conjunction with embodiments, so that those skilled in the art can implement it with reference to the text of the specification.

[0028] It should be understood that terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0029] As Figure 1 shown, a two-chamber electrolysis cell using high-performance plates includes a left end plate 1, a left insulating gasket 2, a cathode single plate 3, a first chamber cathode insulating seal frame 4, a first chamber membrane electrode 5, a first chamber anode insulating seal frame 6, a bipolar plate 7, a second chamber cathode insulating seal frame 8, a second chamber membrane electrode 9, a second chamber anode insulating seal frame 10, an anode single plate 11, a right insulating gasket 12, and a right end plate 13 arranged in sequence. The two-chamber electrolysis cell at least includes a cathode plate with a cathode flow field 100 and an anode plate with an anode flow field 200. Among them, the cathode single plate has a cathode flow field 100, the anode single plate has an anode flow field 200, and the bipolar plate has a cathode flow field 100 and an anode flow field 200. As Figures 2-3As shown, the cathode flow field 100 includes a first electrolyte inlet 110, a first inlet distribution area 120, a first flow channel area 130, a first outlet distribution area 140, and a first electrolyte outlet 150 arranged in sequence along the electrolyte flow direction. The flow channel area of the cathode flow field 100 includes multiple flow channels for the electrolyte to pass through. The flow channel area of the cathode flow field 100 at least includes a cathode straight flow channel area 160 with multiple straight flow channels and a curved flow channel area 170 with multiple bent flow channels 171. The cathode straight flow channel area 160 is evenly arranged on both sides of the curved flow channel area 170; the length of the bent flow channel 171 is 1.1 - 1.3 times the length of the straight flow channel of the cathode. By extending the path length of the electrolyte passing through the bent flow channel 171, the pressure drop of the electrolyte flowing through the curved flow channel area 170 reaches a ratio of 1 - 2 times that of the cathode straight flow channel area 160. At the same time, the overall pressure drop of the cathode flow field 100 is also increased, so that the flow rate of hydrogen is reduced, and the rapid outflow of hydrogen in the cathode flow channel is avoided;

[0030] As Figures 4-5 shown, the anode flow field 200 includes a second electrolyte inlet 210, a second inlet distribution area 220, a second flow channel area 230, a second outlet distribution area 240, and a second electrolyte outlet 250 arranged in sequence along the electrolyte flow direction. The second flow channel area includes multiple flow channels for the electrolyte to pass through. The second flow channel area at least includes an anode straight flow channel area 260 with multiple straight flow channels and a truncated distribution type flow channel area 270 with multiple multi-segment line type flow channels 271. The anode straight flow channel area is evenly arranged on both sides of the truncated distribution type flow channel area; each of the multi-segment line type flow channels is composed of two flow channel ridges 280 with multiple break points 281 evenly and symmetrically distributed; the electrolyte flow directions of the anode straight flow channel area and the cathode straight flow channel area 160 are perpendicular to each other. The bent flow channel 171 is a wavy flow channel; the length of each break point on both flow channel ridges of the multi-segment line type flow channel is not greater than the width of the multi-segment line type flow channel.

[0031] The area of the curved flow channel region 170 accounts for 40%-60% of the area of the first flow channel region. The larger the proportion of the area of the curved flow channel region 170 in the area of the first flow channel region, the greater the overall pressure drop of the cathode flow field 100. In this embodiment, the first flow channel region adopts a combination of straight flow channels on both sides and a curved or variable-diameter flow channel in the middle. One reason for adopting this combined flow channel is that the pressure at the inlet end of the flow channel is higher than that at the outlet end. When the electrolyte flows in the flow field, due to its viscous effect, the electrolyte generates friction with the flow channel during the flow process, resulting in the pressure at the outlet end being lower than that at the inlet end. In actual situations, the pressure loss of the flow channel in the middle part of the flow channel region is relatively small, while the pressure loss of the flow channels on both sides is relatively large. Therefore, a curved or variable-diameter flow channel is adopted in the middle part to increase the pressure loss. In addition, since the amount of hydrogen generated at the cathode is twice that of oxygen at the anode, appropriately increasing the pressure drop at the cathode helps to control the flow rate of hydrogen and prevent it from flowing out too quickly in the flow channel.

[0032] In this embodiment, the bent flow channel 171 is composed of a plurality of relatively gentle S-shaped channels to form a wavy flow channel. The width of the wavy flow channel decreases at its wave crest and / or wave trough (in this embodiment, only at the wave crest). As Figure 3 , 5 shown, the bending, diameter change of the wavy flow channel, and the eddy current and flow velocity changes generated by the truncation in the multi-segment line flow channel will enhance the fluid disturbance in the electrolyte. The generation of eddy currents and flow velocity gradients will accelerate the diffusion process of the reactants in the electrolyte, reduce the concentration polarization phenomenon near the electrode surface, enable the reactants in the electrolyte to reach the electrode surface faster, improve the reaction rate, and at the same time quickly carry the products away from the electrode surface to avoid the inhibitory effect on the reaction. In the electrolytic cell, fluid disturbance can prompt the fluid to contact the electrode surface more evenly and reduce the existence of flow dead zones, thereby increasing the effective utilization area of the electrode. At the same time, during the electrolysis process, bubbles will be generated on the electrode surface. The eddy current and flow velocity changes can effectively reduce the time for bubbles to adhere to the electrode surface, prevent the bubbles from hindering the electrolyte from contacting the electrode surface, and thus maintain the electrolysis efficiency. And it can also increase the cleaning effect of the fluid, carry away the deposited or suspended particulate impurities from the electrode surface, and reduce pollution and blockage problems.

[0033] In this embodiment, the width of the wavy flow channel at its wave crest and / or wave trough is 70% of the width at the remaining flow channel positions. The ratio of the length of a single wavy flow channel to the length of a single straight flow channel is 1.2:1. The pressure drop is proportional to the flow channel length. The length of the wavy flow channel is 20% longer than that of the straight flow channel, which will cause its pressure drop to increase by about 20%. The diameter of the wavy flow channel decreases by 30% at the bending position. The reduction in diameter will significantly increase the local pressure loss. According to Bernoulli's principle and the Darcy-Weisbach formula When the diameter decreases by 30% (i.e., from d0 to 0.7d0), the local pressure drop will increase significantly, about The bending of the wavy channel will introduce eddy currents and secondary flows, which will increase the pressure loss. Generally, the additional pressure loss coefficient is calculated according to empirical formulas. Considering the above factors, the pressure drop of the wavy channel compared to the straight channel can be expressed as the following ratio:

[0034] where Δp is the pressure drop change rate, L is the length, "S-shaped" refers to the wavy channel, and "straight" refers to the straight channel. Since the amount of hydrogen generated during electrolysis is much more than that of oxygen, to avoid the too-fast or controllable outflow of hydrogen, it is considered to appropriately increase the overall pressure drop of the cathode flow field to make it greater than the overall pressure drop of the anode flow field. Specifically, the pressure drop of the curved channel area of the cathode flow field can be significantly increased to improve the overall pressure drop of the cathode flow field. For example, when designing the pressure drop of the wavy channel, a target of twice the pressure drop of the straight channel is adopted, and the length, diameter reduction ratio, and curvature of the wavy channel are optimized according to the above formula, so that the total pressure drop of the wavy channel caused by the increased length, diameter reduction, and bending reaches about twice that of the straight channel.

[0035] There is also a boss 290 with a height not greater than 1 / 3 of the height of the channel ridge in the multi-segment line channel. In this embodiment, the designed height of the boss 290 is 30% of the height of the channel ridge. The boss 290 plays a role in reducing the local channel diameter. The boss 290 is arranged between two symmetric channel ridges (preferably in the middle between two symmetric channel ridges. If the boss is set close to the break point, local flow disorder will occur, and a certain distance should be maintained from the break point). Setting a truncation or a boss 290 on the channel ridge will cause a change in the velocity distribution of the local fluid, enhancing turbulence or perturbation. This effect can increase the mass transfer rate between the fluid and the electrode surface, helping to improve the reaction efficiency. And it can avoid too high a concentration gradient of the reactants and improve the uniformity of the electrolysis process. The truncation and the boss 290 will change the flow path in the channel and suppress the phenomenon of side flow. Setting the boss 290 and truncation in the straight channel can guide the fluid to generate secondary flow, which is beneficial to the detachment of bubbles or particulate impurities from the channel surface and reduces the risk of blockage or local stagnation. The height of the boss 290 does not exceed the height of the channel ridge to avoid completely blocking the mainstream channel flow.

[0036] The materials of the left end plate and the right end plate are stainless steel, titanium or nickel.

[0037] The diffusion layer of the membrane electrode is made of a conductive porous material.

[0038] The left insulating gasket 2, the first chamber cathode insulating sealing frame 4, the first chamber anode insulating sealing frame 6, the second chamber cathode insulating sealing frame 8, the second chamber anode insulating sealing frame 10, and the right insulating gasket 12 are all made of insulating and corrosion-resistant materials, and the insulating and corrosion-resistant materials at least include materials such as PTFE, PP, PPS, silica gel, or fluororubber.

[0039] Figure 6 It is a performance test comparison chart (1M KOH, 1A / cm² @ 60°C) of an optimized electrolysis unit of the present invention and a conventional electrolysis unit (only a common direct flow channel is used in the flow field). The maximum fluctuation of the conventional electrolysis unit is 6.6 mV, and the maximum fluctuation of the test voltage of the optimized electrolysis unit of the present invention is reduced to about 3.6 mV. It can be seen that the flow field structure layout of the present invention better ensures the stability of the electrolysis unit during operation.

[0040] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A dual-chamber electrolysis unit using high-performance plates, characterized in that: The dual-chamber electrolysis unit at least comprises a cathode monopolar plate having a cathode flow field and an anode monopolar plate having an anode flow field, wherein the cathode flow field comprises a first electrolyte inlet, a first inlet distribution area, a first flow channel area, a first outlet distribution area and a first electrolyte outlet arranged in sequence along the flow direction of the electrolyte, the flow channel area of ​​the cathode flow field comprises a plurality of flow channels for the electrolyte to pass through, the flow channel area of ​​the cathode flow field comprises at least a cathode linear flow channel area having a plurality of direct current channels and a curved flow channel area having a plurality of curved flow channels, the cathode linear flow channel area being evenly arranged on both sides of the curved flow channel area; the length of the curved flow channel is 1.1-1.3 times the length of the direct current channel; by extending the path length of the electrolyte passing through the curved flow channel, the pressure drop of the electrolyte flowing through the curved flow channel area is 1-2 times the pressure drop of the cathode linear flow channel area, and the overall pressure drop of the cathode flow field is also increased, so that the flow rate of hydrogen is reduced, and the hydrogen in the cathode flow channel is prevented from flowing out too quickly; The anode flow field includes a second electrolyte inlet, a second inlet distribution area, a second flow channel area, a second outlet distribution area and a second electrolyte outlet arranged in sequence along the electrolyte flow direction. The second flow channel area includes multiple flow channels for electrolyte to pass through. The second flow channel area at least includes an anode linear flow channel area with multiple direct current channels and a truncated distributed flow channel area with multiple multi-segment linear flow channels. The anode linear flow channel area is evenly arranged on both sides of the truncated distributed flow channel area; each of the multi-segment linear flow channels is composed of two flow channel ridges with multiple breakpoints evenly and symmetrically distributed; the electrolyte flow directions of the anode linear flow channel area and the cathode linear flow channel area are perpendicular to each other.

2. The double-chamber electrolysis unit using high-performance plates according to claim 1, characterized in that: The bent flow channel is a wavy line flow channel; the length of each breakpoint on the flow channel ridges on both sides of the multi-segment linear flow channel is not greater than the width of the multi-segment linear flow channel.

3. The dual-chamber electrolysis unit using high-performance plates according to claim 2, characterized in that: The area of ​​the curved flow channel region accounts for 40%-60% of the area of ​​the first flow channel region.

4. The dual-chamber electrolysis unit using high-performance plates according to claim 2, characterized in that: The width of the wave-line flow channel decreases at the wave crests and / or wave troughs.

5. The double-chamber electrolysis unit using high-performance plates according to claim 4, characterized in that: The width of the wave-line flow channel at its wave crest and / or wave trough is not less than 70% of the width of the remaining flow channel positions.

6. The dual-chamber electrolysis unit using high-performance plates according to claim 2, characterized in that: A boss with a height no greater than 1 / 3 of the height of the flow channel ridge is also provided in the multi-segment linear flow channel, and the boss is provided between two symmetrical flow channel ridges.

7. The dual-chamber electrolysis unit using high-performance plates according to claim 1, characterized in that: The dual-chamber electrolysis unit includes a left end plate, a left insulating sealing gasket, a cathode monopolar plate, a first chamber cathode insulating sealing frame, a first chamber membrane electrode, a first chamber anode insulating sealing frame, a bipolar plate, a second chamber cathode insulating sealing frame, a second chamber membrane electrode, a second chamber anode insulating sealing frame, an anode monopolar plate, a right insulating sealing gasket and a right end plate, wherein the cathode monopolar plate has a cathode flow field, the anode monopolar plate has an anode flow field, and the bipolar plate has a cathode flow field and an anode flow field.

8. The dual-chamber electrolysis unit using high-performance plates according to claim 7, characterized in that: The left end plate and the right end plate are made of stainless steel, titanium or nickel.

9. The dual-chamber electrolysis unit using high-performance plates according to claim 7, characterized in that: The diffusion layer of the membrane electrode is made of conductive porous material.

10. The dual-chamber electrolysis unit using high-performance plates according to claim 7, characterized in that: The left insulating sealing gasket, the first chamber cathode insulating sealing frame, the first chamber anode insulating sealing frame, the second chamber cathode insulating sealing frame, the second chamber anode insulating sealing frame and the right insulating sealing gasket are all made of insulating corrosion-resistant materials, and the insulating corrosion-resistant materials include at least one of PTFE, PP, PPS, silicone or fluororubber materials.

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