A low energy consumption zero gap electrolyzer structure for alkaline water electrolysis

Abstract

The application discloses a low-energy-consumption zero-polar-distance electrolytic cell structure for alkaline water electrolysis, and particularly relates to the technical field of hydrogen energy, which comprises a frame plate, an anode current collector, a cathode current collector, an anode electrode net, a cathode electrode net and a diaphragm arranged between the anode electrode net and the cathode electrode net, and further comprises an elastic assembly arranged between the cathode current collector and the cathode electrode net and used for pressing the cathode current collector, the cathode electrode net, the diaphragm, the anode electrode net and the anode current collector in sequence so that the anode electrode net and the cathode electrode net are tightly attached to two sides of the diaphragm. The low-energy-consumption zero-polar-distance electrolytic cell structure for alkaline water electrolysis realizes the zero-polar-distance structure that the anode electrode net and the cathode electrode net are tightly attached to two sides of the diaphragm through the elastic assembly, greatly shortens an ion transmission path, reduces ohmic polarization loss, and thus reduces electrolysis voltage.

Description

Technical Field

[0001] This invention relates to the field of hydrogen energy technology, and in particular to a low-energy-consumption, zero-gap electrolyzer structure for alkaline water electrolysis. Background Technology

[0002] Hydrogen energy, as an important zero-carbon energy carrier for achieving dual-carbon goals, has received widespread attention in recent years. Among numerous hydrogen production technologies, alkaline water electrolysis is considered one of the most promising green hydrogen production technologies for industrial application due to its high technological maturity, long service life, and relatively low system cost. However, traditional alkaline electrolyzers still face several technical bottlenecks in their structural design, hindering their further development towards high energy efficiency and low energy consumption. First, traditional electrolyzers generally adopt a parallel plate structure, with a spacing of 3–10 mm or even larger between the cathode and anode electrodes. This large electrode spacing easily leads to the formation of an electrolyte concentration gradient and promotes the accumulation of bubbles on the electrode surface, resulting in severe concentration polarization, increasing cell voltage, and reducing electrolysis efficiency. Second, existing electrolyzers lack systematic optimization in the design of electrolyte flow paths, relying heavily on natural diffusion and free convection for mass transfer, making it difficult to effectively remove gas evolution products. This results in a high degree of gas-liquid phase mixing and low mass transfer efficiency, thus affecting the stable operation and energy consumption of the system.

[0003] Furthermore, traditional membrane materials are mostly porous, which are prone to expansion or deterioration in high-temperature, high-concentration alkaline media such as KOH or NaOH, resulting in significant ion transport resistance and further increasing the system's operating voltage. Meanwhile, existing catalytic materials largely rely on precious metals such as platinum and iridium, which not only increases electrode costs but also limits the large-scale adoption of alkaline water electrolysis technology.

[0004] To address the aforementioned issues, existing technologies have proposed a zero-gap structure concept, which involves arranging the anode and cathode close to the diaphragm to minimize the inter-electrode distance and reduce ohmic losses. Simultaneously, by introducing a flow-guiding structure inside the electrolyzer, the electrolyte flow path is optimized, improving local mass transfer and suppressing gas backmixing, providing a new technical approach to reducing concentration polarization and system energy consumption. However, achieving a coordinated design of the zero-gap structure and the circulation channel while ensuring structural sealing, manufacturability, flow-guiding efficiency, and electrode clamping performance remains a key technical challenge in current engineering practice. Summary of the Invention

[0005] The main objective of this invention is to provide a low-energy-consumption, zero-gap electrolyzer structure for alkaline water electrolysis, which can effectively solve the problems of high ohmic polarization loss caused by large electrode spacing in existing alkaline water electrolyzers, severe concentration polarization and obvious gas backmixing caused by unoptimized electrolyte flow path, as well as the resulting high energy consumption for hydrogen production and low mass transfer efficiency.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A low-energy-consumption, zero-gap electrolyzer structure for alkaline water electrolysis includes a frame plate, an anode current collector, a cathode current collector, an anode electrode mesh, a cathode electrode mesh, and a diaphragm disposed between the anode electrode mesh and the cathode electrode mesh. Unlike existing technologies, this electrolyzer structure also includes an elastic component, a circulation guide plate, a liquid distribution pipe, and a gas-liquid separation device.

[0007] The elastic component is disposed between the cathode current collector and the cathode electrode mesh. This elastic component sequentially presses the cathode current collector, the cathode electrode mesh, the diaphragm, the anode electrode mesh, and the anode current collector together, ensuring that the anode electrode mesh and the cathode electrode mesh are tightly attached to both sides of the diaphragm, thereby achieving a zero-gap arrangement. Using this pressing method, the inter-electrode distance approaches zero, effectively eliminating the ohmic resistance caused by the electrolyte layer in traditional electrolytic cells and reducing ohmic polarization losses.

[0008] The circulation guide plate is inclinedly disposed on the side of the anode electrode mesh and / or the cathode electrode mesh away from the diaphragm, forming an electrolyte flow channel between itself and the corresponding electrode mesh surface. This inclined flow guide structure can guide the electrolyte to flow directionally from bottom to top along the electrode mesh surface, forming a stable natural circulation flow field, thereby enhancing mass transfer on the electrode surface and significantly alleviating concentration polarization caused by bubble aggregation.

[0009] The liquid distribution pipe is located at the bottom of the gas chamber, and its outlet is opposite to the inlet of the electrolyte flow channel. This liquid distribution pipe allows the electrolyte to be evenly distributed to the bottom of the flow channel, preventing localized flow short circuits or dead zones and ensuring the uniformity of the mass transfer process.

[0010] The gas-liquid separation device is located at the top of the gas chamber, and its inlet is opposite to the outlet of the electrolyte flow channel. Gas generated by the electrolyte and electrode surface rises within the flow channel and enters the gas-liquid separation device, achieving rapid gas-liquid separation. The gas is discharged from the top, and the separated electrolyte is recycled, effectively suppressing gas back-mixing and further improving electrolysis efficiency.

[0011] Preferably, the elastic component is nickel foam or a wave spring. The high porosity and elasticity of nickel foam ensure uniform clamping without hindering electrolyte flow, while the wave spring provides stable clamping force; both contribute to reducing contact resistance.

[0012] Preferably, the distance between the circulation guide plate and the corresponding electrode mesh surface is 5-20 mm, and the circulation guide plate gradually widens or slopes at a constant width from top to bottom along the electrolyte flow direction. This distance and shape design facilitates the formation of a stable natural circulation flow, avoids channel blockage or short circuit, and ensures smooth discharge of bubbles.

[0013] Preferably, the circulation guide plate is narrower at the top and wider at the bottom, with an overall tilt angle of 5°-30°, and the surface of the circulation guide plate facing the electrode mesh is a hydrophilic surface. The hydrophilic surface helps bubbles to quickly detach from the electrode surface, reducing the activation overpotential caused by bubble coverage and further enhancing electrode activity.

[0014] Preferably, the liquid distribution pipe has multiple liquid distribution holes evenly distributed on it, and the liquid distribution pipe is located at the bottom or below the side of the gas chamber. This arrangement ensures that the electrolyte enters the flow channel evenly from the bottom, eliminates flow dead zones, and improves the utilization efficiency of the entire electrode area.

[0015] Preferably, the gas-liquid separation device includes a gas outlet pipe and a liquid outlet pipe, with the gas outlet pipe located at the top of the device and the liquid outlet pipe located at the bottom. The separated gas is discharged cleanly from the top, while the electrolyte flows back to the circulation system from the bottom, achieving continuous and stable operation.

[0016] Preferably, the anode electrode mesh and / or the cathode electrode mesh are coated with a non-precious metal catalyst layer. Non-precious metal catalysts can significantly reduce oxygen evolution overpotential and hydrogen evolution overpotential, while avoiding the use of precious metals, reducing material costs, and maintaining high catalytic activity.

[0017] Preferably, the catalyst layer on the anode electrode grid is a Raney nickel coating, and the catalyst layer on the cathode electrode grid is a nickel-molybdenum alloy coating. Raney nickel has a large specific surface area and excellent oxygen evolution performance, while nickel-molybdenum alloys exhibit high activity and long-term stability for the hydrogen evolution reaction in alkaline media.

[0018] Preferably, the diaphragm is a polyphenylene sulfide-based reinforced composite diaphragm with a sheet resistivity of less than 0.2 Ω·cm² in a 30 wt% KOH solution at 30°C. Using this low sheet resistivity diaphragm can further reduce ion transport resistance, decrease ohmic losses, and simultaneously withstand corrosion from high-temperature, high-concentration alkaline solutions.

[0019] Preferably, the gas chamber includes an oxygen chamber and a hydrogen chamber, with the oxygen chamber located on the outer side of the anode electrode grid and the hydrogen chamber located on the outer side of the cathode electrode grid. This independent gas chamber design effectively isolates the oxygen generated at the anode and the hydrogen generated at the cathode, preventing hydrogen-oxygen mixing and improving system safety.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a low-energy-consumption zero-gap electrolyzer structure for alkaline water electrolysis. Through elastic components, a zero-gap structure is achieved in which the anode electrode mesh and the cathode electrode mesh are tightly attached to both sides of the diaphragm, which greatly shortens the ion transport path, reduces ohmic polarization loss, and thus reduces the electrolysis voltage.

[0021] 2. This invention provides a low-energy-consumption zero-gap electrolyzer structure for alkaline water electrolysis. Through the synergistic effect of the inclined circulation guide plate, liquid distribution pipe and gas-liquid separation device, a directional and stable natural circulation flow field of electrolyte is formed, which effectively enhances mass transfer on the electrode surface, suppresses bubble aggregation and back mixing, greatly alleviates concentration polarization, and further improves the operating efficiency under current density.

[0022] 3. This invention provides a low-energy-consumption zero-gap electrolyzer structure for alkaline water electrolysis. By combining a non-precious metal catalyst coating with a low surface resistance composite membrane, the activation overpotential and ion transport resistance are further reduced, enabling the electrolyzer to achieve stable low-energy-consumption operation within a wide current density range of 2000-10000 A / m², with a unit hydrogen production energy consumption of less than 4.2 kWh / Nm³H2. Attached Figure Description

[0023] Fig. 1 A comparison of current density-slot voltage curves before and after the addition of the circulating guide plate; Fig. 2 A comparison of current density-cell voltage curves for electrolysis processes of different elastic materials; Fig. 3 A comparison of current density-cell voltage curves during electrolysis using different catalyst electrode grids. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0025] Example 1 This embodiment provides a low-energy-consumption, zero-gap electrolyzer structure for alkaline water electrolysis, the specific structure of which is as follows.

[0026] Reference Figs. 1-3 As shown, the electrolytic cell structure mainly includes: a frame plate, a high-temperature resistant silicone gasket, an oxygen chamber, a hydrogen chamber, an anode current collector, an anode electrode mesh, a cathode current collector, a cathode electrode mesh, a composite diaphragm, a liquid distribution pipe, a gas-liquid separation device, a circulation guide plate, and elastic components.

[0027] Specifically, in this embodiment, all frame plates and gas chambers such as the oxygen chamber and hydrogen chamber are machined from 316L stainless steel. The anode and cathode current collectors are made of nickel-plated copper porous plates to reduce contact resistance. Both the anode and cathode electrode meshes are made of 80-mesh Ni6 nickel mesh.

[0028] One of the core structural features of this embodiment lies in the design of the zero-pitch component. For example... Fig. 2 As shown, from the cathode side to the anode side, the stacking order of the components is as follows: cathode current collector, elastic component, cathode electrode mesh, composite diaphragm, anode electrode mesh, and anode current collector. The elastic component is made of 2mm thick nickel foam with a porosity of 95%. Through mechanical compression, the nickel foam undergoes approximately 30% compression deformation, thus tightly pressing the cathode electrode mesh, composite diaphragm, and anode electrode mesh together. In this structure, both the cathode and anode electrode meshes are directly attached to both sides of the composite diaphragm, with no free electrolyte layer between them, eliminating the ohmic resistance caused by the electrode spacing in traditional electrolytic cells and achieving a zero-gap design. Gaskets are placed on the mating surfaces of the components, such as between the frame plate and the current collector, and between the current collector and the electrode mesh, and are secured with bolts to form a reliable seal.

[0029] Another core structural feature of this embodiment is the inclined circulation guide plate. A circulation guide plate is installed on the outer side of both the anode and cathode electrode meshes, i.e., on the side furthest from the diaphragm. This guide plate is made of 316L stainless steel, and its surface is sandblasted to enhance hydrophilicity. The geometric features of the guide plate are: the plate is narrower at the top and wider at the bottom, with an overall inclination angle of 15°, sloping from top to bottom, and the distance between the guide plate and the corresponding electrode mesh surface is 12mm. The bottom edge of the guide plate is opposite to the outlet of the liquid distribution pipe located below the side of the gas chamber, and the top edge is opposite to the inlet of the gas-liquid separation device located above the side of the gas chamber.

[0030] The electrolyte circulation path is as follows: The electrolyte is pumped into the distribution pipe located below the oxygen and hydrogen chambers via an external circulation pump. Distribution holes are evenly distributed on the distribution pipe, through which the electrolyte enters the electrode chamber. Guided by the baffle plate, the electrolyte flows upwards along the electrode mesh surface. Gas generated on the electrode surface carries the electrolyte upwards during its ascent, entering the upper gas-liquid separator. Oxygen is generated at the anode, and hydrogen at the cathode. In the gas-liquid separator, the gas is discharged and collected through the upper outlet pipe, while the separated electrolyte flows back to the electrolyte circulation system through the lower outlet pipe, achieving recycling. The presence of the baffle plate effectively prevents gas accumulation and backmixing on the electrode surface, forming a stable natural circulation flow field, significantly enhancing the mass transfer process on the electrode surface and reducing concentration polarization.

[0031] Furthermore, the electrode mesh was catalytically modified in this embodiment. The anode electrode mesh was coated with a Raney nickel non-precious metal catalyst by electrodeposition, with a coating thickness of approximately 50 μm. The cathode electrode mesh was coated with a nickel-molybdenum based non-precious metal catalyst, with a coating thickness of approximately 40 μm. The composite membrane was a commercially available polyphenylene sulfide-based reinforced composite membrane, with a sheet resistivity of less than 0.2 Ω·cm² in a 30 wt% KOH solution at 30 °C, exhibiting low resistance, high alkali corrosion resistance, and excellent mechanical strength.

[0032] Performance testing: A single electrolysis chamber was assembled according to Example 1 above, and its performance was tested under the following standard operating conditions: operating temperature 80±2℃, electrolyte 30wt% KOH aqueous solution, and operating pressure 0.1MPa. A DC power supply was used to measure the cell voltage under different current densities, and the corresponding hydrogen production energy consumption was calculated.

[0033] The test results are as follows: At a current density of 3000 A / m², the cell voltage was measured to be 1.75 V, and the energy consumption per unit of hydrogen production was calculated to be approximately 4.20 kWh / Nm³H₂.

[0034] At a current density of 5000 A / m², the cell voltage was measured to be 1.82 V, and the energy consumption per unit of hydrogen production was calculated to be approximately 4.37 kWh / Nm³H₂.

[0035] At a current density of 8000 A / m², the cell voltage was measured to be 1.92 V, and the energy consumption per unit of hydrogen production was calculated to be approximately 4.61 kWh / Nm³H₂.

[0036] The above test results show that, under all test current densities, especially in the design range of 2000-10000 A / m², the electrolyzer structure of this embodiment can achieve extremely low hydrogen production energy consumption, and the energy consumption at 3000 A / m² is already lower than the target value of 4.2 kWh / Nm³H2.

[0037] Comparative test To verify the technical effect of the present invention, the following comparative experiment was conducted: Comparative Example 1 without a deflector: The structure is basically the same as that of Example 1, but the circulation deflector is removed, and the other conditions remain unchanged.

[0038] Comparative Example 2: No zero-pitch structure: The structure is basically the same as that of Example 1, but the foamed nickel elastic component is removed, so that the distance between the cathode electrode mesh and the anode electrode mesh is fixed at 4 mm, and the other conditions remain unchanged.

[0039] Comparative Example 3: Traditional structure: adopts traditional parallel plate structure, electrode spacing 4mm, no guide plate, no catalyst coating on electrode mesh, and uses ordinary PPS diaphragm.

[0040] Under the same test conditions with a current density of 5000 A / m², the performance of each comparative sample is compared with that of Example 1 as follows: Comparative results analysis: Compared with Comparative Example 1, the cell voltage of Example 1 decreased by 0.60V, proving that the flow guide plate structure of the present invention can effectively reduce concentration polarization; compared with Comparative Example 2, the cell voltage of Example 1 decreased by 0.33V, proving that the zero-gap structure can effectively reduce ohmic polarization; compared with the completely conventional Comparative Example 3, the cell voltage of Example 1 decreased by 0.88V, and the hydrogen production energy consumption decreased by about 32.5%, showing significant technical effects.

[0041] In summary, the electrolyzer structure provided in this embodiment, through the synergistic effect of the inclined guide plate and the zero-gap component, combined with the non-precious metal catalyst and the low-resistance composite membrane, successfully solves the problems of severe concentration polarization and ohmic polarization in traditional alkaline electrolyzers, achieving stable operation with low energy consumption under high current density, and fully achieving the technical effects claimed by this invention.

[0042] The working principle of this low-energy-consumption zero-gap electrolyzer structure used for alkaline water electrolysis will be explained in detail below.

[0043] like Figs. 1-3 As shown, the electrolyte is pumped into the distribution pipe by an external circulation pump, and then enters the oxygen chamber and hydrogen chamber through the distribution holes. Guided by the inclined circulation guide plates, the electrolyte forms a directional natural circulation flow from bottom to top along the surfaces of the anode and cathode electrode grids. During electrolysis, oxygen is released on the surface of the anode grid and hydrogen is released on the surface of the cathode grid. The rising bubbles carry the electrolyte upward and into the gas-liquid separation device above the side of the gas chamber. The gas is discharged and collected through the gas outlet pipe, and the separated electrolyte flows back to the circulation system through the liquid outlet pipe, thereby effectively avoiding gas accumulation and back mixing on the electrode surface and significantly alleviating concentration polarization. At the same time, elastic components such as nickel foam are used to connect the cathode current collector, cathode electrode grid, composite diaphragm, anode electrode grid, and anode current collector. By sequentially and tightly pressing the two electrode meshes together, the two electrode meshes are directly attached to both sides of the diaphragm, with the inter-electrode distance approaching zero. This eliminates the ohmic resistance caused by electrolyte and air bubbles in the traditional inter-electrode distance. In addition, the electrode meshes are coated with non-precious metal catalysts such as Raney nickel and nickel-molybdenum to reduce the oxygen / hydrogen evolution overpotential. The composite diaphragm provides low ion transport resistance. With the synergistic effect of the flow guide plate enhancing mass transfer, the zero-gap structure reducing ohmic losses, and the catalytic material reducing the activation overpotential, the concentration polarization, ohmic polarization, and activation polarization of the electrolyzer as a whole are significantly suppressed. As a result, the energy consumption for hydrogen production is reduced to below 4.2 kWh / Nm³H2 in the current density range of 2000-10000 A / m², achieving high-efficiency, low-energy-consumption, and stable operation of alkaline water electrolysis for hydrogen production.

[0044] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A low-energy-consumption, zero-gap electrolytic cell structure for alkaline water electrolysis, comprising a frame plate, an anode current collector, a cathode current collector, an anode electrode mesh, a cathode electrode mesh, and a diaphragm disposed between the anode electrode mesh and the cathode electrode mesh, characterized in that, Also includes: An elastic component is disposed between the cathode current collector and the cathode electrode mesh, and is used to sequentially press the cathode current collector, the cathode electrode mesh, the diaphragm, the anode electrode mesh and the anode current collector together so that the anode electrode mesh and the cathode electrode mesh are both tightly attached to both sides of the diaphragm; A circulation guide plate is inclinedly disposed on the side of the anode electrode mesh and / or the cathode electrode mesh away from the diaphragm, and forms an electrolyte flow channel between the circulation guide plate and the corresponding electrode mesh surface; A liquid distribution pipe is provided at the lower part of the gas chamber, and the outlet of the liquid distribution pipe is opposite to the inlet of the electrolyte guiding channel. A gas-liquid separation device is disposed at the upper part of the gas chamber, and the inlet of the gas-liquid separation device is opposite to the outlet of the electrolyte guiding channel.

2. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The elastic component is a nickel foam or a wave spring. When the elastic component is compressed, the anode electrode mesh and the cathode electrode mesh are tightly attached to both sides of the diaphragm.

3. The low-energy-consumption, zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The distance between the circulation guide plate and the corresponding electrode mesh surface is 5-20mm. The circulation guide plate gradually widens or is inclined at the same width from top to bottom along the electrolyte flow direction.

4. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The circulation guide plate is narrower at the top and wider at the bottom, with an overall tilt angle of 5°-30°, and the surface of the circulation guide plate facing the electrode mesh is a hydrophilic surface.

5. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The liquid distribution pipe has multiple liquid distribution holes evenly distributed on it, and the liquid distribution pipe is located at the bottom or below the side of the gas chamber.

6. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The gas-liquid separation device includes a gas outlet pipe and a liquid outlet pipe. The gas outlet pipe is located at the top of the gas-liquid separation device, and the liquid outlet pipe is located at the bottom of the gas-liquid separation device.

7. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The anode electrode mesh and / or the cathode electrode mesh are coated with a non-precious metal catalyst layer.

8. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The catalyst layer on the anode electrode grid is a Raney nickel coating, and the catalyst layer on the cathode electrode grid is a nickel-molybdenum alloy coating.

9. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The diaphragm is a polyphenylene sulfide-based reinforced composite diaphragm, and its sheet resistance is less than 0.2 Ω·cm² in a 30 wt% KOH solution at 30 °C.

10. The low-energy-consumption zero-gap electrolytic cell structure for alkaline water electrolysis according to claim 1, characterized in that: The gas chamber includes an oxygen chamber and a hydrogen chamber. The oxygen chamber is disposed on the outside of the anode electrode grid, and the hydrogen chamber is disposed on the outside of the cathode electrode grid.

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