An asymmetric electrolytic cell

Abstract

This application discloses an asymmetric electrolyzer. The asymmetric electrolyzer includes an electrolysis chamber, which comprises a diaphragm, a cathode chamber, and an anode chamber. The cathode chamber contains a cathode distribution layer, and the anode chamber contains an anode distribution layer. The cathode chamber has a hydrogen-side alkali channel for circulating alkali and a hydrogen channel for discharging hydrogen. The anode chamber has an oxygen-side alkali channel for circulating alkali and an oxygen channel for discharging oxygen. The cathode chamber has a larger size than the anode chamber; the pore size of the hydrogen channel is larger than that of the oxygen channel; the pore size of the hydrogen-side alkali channel is larger than that of the oxygen-side alkali channel; and the porosity of the cathode distribution layer is greater than that of the anode distribution layer. The asymmetric electrolyzer provided in this application, by setting up a chamber with an asymmetric structure, maintains pressure balance on both the hydrogen and oxygen sides within the electrolyzer body, achieving rapid pressure regulation within the electrolyzer and effectively preventing the mutual transfer of oxygen and hydrogen.

Description

Technical Field

[0001] This application relates to the field of water electrolysis hydrogen production equipment technology, and in particular to an asymmetric electrolyzer. Background Technology

[0002] The randomness and volatility of renewable energy sources such as wind and solar power pose significant challenges to the stability and security of power grids. Large-scale renewable energy coupled with hydrogen electrolysis not only effectively improves the energy efficiency of renewable energy power generation systems but also effectively solves the "where does the hydrogen come from?" problem in the green hydrogen energy industry, possessing significant strategic importance and becoming an energy strategy for many countries. Hydrogen production technologies include alkaline water electrolysis, proton exchange membrane water electrolysis, anion exchange membrane water electrolysis, and solid oxide electrolysis. Alkaline electrolyzers are currently the only water electrolysis hydrogen production equipment suitable for large-scale engineering applications, possessing advantages such as mature technology and low cost, and holding a 99% market share in total installed capacity.

[0003] An alkaline electrolyzer consists of components such as a diaphragm and electrodes. The diaphragm is porous, allowing gas to easily pass through when there is a pressure difference on both sides. Maintaining pressure balance between the hydrogen and oxygen sides of the electrolyzer typically involves adjusting the opening and closing frequency of the outlet valve to maintain the pressure difference in the gas-liquid separator. Patent 202210589386.9 achieves high-precision active pressure control of the electrolyzer by acquiring external input power in real time and employing two different pressure regulating valves: one with high precision and high flow rate, and the other with low precision and low flow rate. Patent 202110968038.8 installs a safety device on the U-shaped tube between the two gas-liquid separators in the alkaline electrolysis system to suppress the risk of cross-gas flow, overcoming the defect that changes in the electrolysis power of the alkaline electrolysis system can disrupt the liquid level balance in the U-shaped tube, leading to cross-gas flow. The methods provided by the above patents all involve pressure regulation from the external system of the electrolyzer. However, there is a time difference in the transmission of pressure regulation from the external system to the internal pressure of the electrolyzer. This time difference is much greater than the rate of hydrogen production by electrolysis. Especially when the hydrogen production load of the electrolyzer is low, the volume of generated gas is relatively low, and the transmission of this external pressure regulation to the inside of the electrolyzer is relatively slow, which is not conducive to the rapid adjustment of the pressure inside the electrolyzer. Summary of the Invention

[0004] The purpose of this application is to provide an asymmetric electrolyzer that maintains pressure balance between hydrogen and oxygen within the electrolyzer body by setting up a chamber with an asymmetric structure, thereby achieving rapid pressure regulation within the electrolyzer and effectively preventing the mutual transfer of oxygen and hydrogen.

[0005] This application provides an asymmetric electrolytic cell, comprising: an electrolysis chamber, the electrolysis chamber including a diaphragm, a cathode chamber and an anode chamber respectively located on opposite sides of the diaphragm; the cathode chamber is provided with a cathode distribution layer, and the anode chamber is provided with an anode distribution layer; the cathode chamber is provided with a hydrogen-side alkali channel for circulating alkali solution and a hydrogen channel for discharging hydrogen gas, and the anode chamber is provided with an oxygen-side alkali channel for circulating alkali solution and an oxygen channel for discharging oxygen gas; the size of the cathode chamber is larger than the size of the anode chamber, the pore size of the hydrogen channel is larger than the pore size of the oxygen channel, the pore size of the hydrogen-side alkali channel is larger than the pore size of the oxygen-side alkali channel, and the porosity of the cathode distribution layer is greater than the porosity of the anode distribution layer.

[0006] Optionally, the cathode distribution layer comprises a cathode flow field layer, a cathode redistribution layer, and a cathode micropore layer stacked sequentially; the anode distribution layer comprises an anode flow field layer, an anode redistribution layer, and an anode micropore layer stacked sequentially; the aperture of the cathode flow field holes on the cathode flow field layer is larger than that of the anode flow field holes on the anode flow field layer; the aperture of the cathode redistribution holes on the cathode redistribution layer is larger than that of the anode redistribution holes on the anode redistribution layer; and the aperture of the cathode micropores on the cathode micropore layer is larger than that of the anode micropores on the anode micropore layer.

[0007] Optionally, the asymmetric electrolytic cell further includes a first bipolar plate attached to one side of the cathode distribution layer and a second bipolar plate attached to one side of the anode distribution layer; the hydrogen-side alkali channel passes through the first bipolar plate in a straight line and is connected to the cathode flow field layer; the oxygen-side alkali channel passes through the second bipolar plate in a straight line and is connected to the anode flow field layer.

[0008] Optionally, the cathode flow field hole is a through hole connecting the first bipolar plate and the cathode redistribution layer, and the anode flow field hole is a bent hole connecting the second bipolar plate and the anode redistribution layer.

[0009] Optionally, the porosity of the cathode microporous layer is greater than that of the anode microporous layer.

[0010] Optionally, the thickness of the cathode distribution layer is twice the thickness of the anode distribution layer.

[0011] Optionally, the aperture size of the hydrogen-side alkaline solution channel is twice that of the oxygen-side alkaline solution channel.

[0012] Optionally, the aperture size of the hydrogen channel is twice that of the aperture size of the oxygen channel.

[0013] Optionally, a first catalyst layer is provided between the diaphragm and the cathode microporous layer, and a second catalyst layer is provided between the diaphragm and the anode microporous layer.

[0014] Optionally, the asymmetric electrolytic cell further includes a first pressure plate portion and a second pressure plate portion, with a plurality of electrolytic chambers arranged sequentially between the first pressure plate portion and the second pressure plate portion; the first pressure plate portion includes a first end pressure plate, a first insulating plate, and a first power extraction plate that are sequentially attached; the second pressure plate portion includes a second end pressure plate, a second insulating plate, and a second power extraction plate that are sequentially attached.

[0015] The above technical solution has the following beneficial effects:

[0016] The asymmetric electrolyzer provided in this application has a cathode chamber with a larger size than the anode chamber to accommodate electrolysis conditions where hydrogen production is greater than oxygen production. The aperture size of the hydrogen channel is larger than that of the oxygen channel to increase the hydrogen discharge rate. The alkali solution and hydrogen produced after electrolysis in the cathode chamber are discharged together from the hydrogen outlet. The alkali solution carries some hydrogen; increasing the aperture size of the alkali solution channel on the hydrogen side provides sufficient space for hydrogen evolution in the circulating alkali solution within the cathode chamber. The porosity of the cathode distribution layer is greater than that of the anode distribution layer, ensuring that the diffusion rate of alkali solution and hydrogen in the cathode chamber is greater than that in the anode chamber. By using the aforementioned asymmetric design to reduce the size of the cathode chamber and its internal structure, as well as the anode chamber and its internal structure, the hydrogen discharge rate from the cathode chamber is accelerated, and the average pressure within the cathode chamber is reduced to accommodate electrolysis conditions where hydrogen production is greater than oxygen production. This maintains pressure balance between the cathode and anode chambers from within the electrolysis chambers, enabling rapid pressure regulation within the electrolyzer and effectively preventing the exchange of oxygen and hydrogen. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an asymmetric electrolytic cell in one embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the structure of the cathode distribution layer in one embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the structure of the anode distribution layer in one embodiment of this application.

[0020] Attached icon number

[0021] 1-Electrolysis chamber;

[0022] 10-September;

[0023] 11-Cathode chamber, 110-Cathode distribution layer, 111-Cathode flow field layer, 112-Cathode flow field hole, 113-Cathode redistribution layer, 114-Cathode micropore layer, 115-Hydrogen-side alkaline solution channel, 116-Hydrogen channel, 117-First bipolar plate;

[0024] 12-Anode chamber, 120-Anode distribution layer, 121-Anode flow field layer, 122-Anode flow field hole, 123-Anode redistribution layer, 124-Anode microporous layer, 125-Oxygen-side alkaline channel, 126-Oxygen channel, 127-Second bipolar plate;

[0025] 13 - First catalyst layer, 14 - Second catalyst layer;

[0026] 2-First pressure plate, 20-First end pressure plate, 21-First insulating plate, 22-First power extraction plate;

[0027] 3-Second pressure plate, 30-Second end pressure plate, 31-Second insulating plate, 32-Second power extraction plate. Detailed Implementation

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0029] It is readily understood that, based on the technical solution of this invention, various structural and implementation methods can be interchanged by those skilled in the art without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of the invention.

[0030] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. They are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive.

[0031] This application provides an asymmetric electrolytic cell, comprising: an electrolysis chamber 1, wherein the electrolysis chamber 1 includes a diaphragm 10, a cathode chamber 11 and an anode chamber 12 respectively located on opposite sides of the diaphragm 10, the cathode chamber 11 having a cathode distribution layer 110, and the anode chamber 12 having an anode distribution layer 120. Alkali solution is electrolyzed in the cathode chamber 11 to produce hydrogen gas, and in the anode chamber 12 to produce oxygen gas.

[0032] The cathode chamber 11 is provided with a hydrogen-side alkali solution channel 115 for circulating alkali solution and a hydrogen gas channel 116 for discharging hydrogen gas. The anode chamber 12 is provided with an oxygen-side alkali solution channel 125 for circulating alkali solution and an oxygen gas channel 126 for discharging oxygen gas.

[0033] The size of the cathode chamber 11 is larger than that of the anode chamber 12 to accommodate electrolysis conditions where the hydrogen yield is greater than the oxygen yield, thereby reducing the average pressure inside the cathode chamber 11.

[0034] The aperture size of the hydrogen channel 116 is larger than that of the oxygen channel 126 to increase the hydrogen discharge rate, which helps to reduce the average pressure in the cathode chamber 11.

[0035] The aperture size of the hydrogen-side alkaline solution channel 115 is larger than that of the oxygen-side alkaline solution channel 125. The alkaline solution and hydrogen gas after electrolysis in the cathode chamber 11 are discharged together through the hydrogen gas channel 116. The alkaline solution after electrolysis carries some hydrogen gas. Increasing the aperture size of the hydrogen-side alkaline solution channel 115 can provide sufficient space for the alkaline solution circulating in the cathode chamber 11 to precipitate hydrogen gas, which is beneficial to reducing the average pressure in the cathode chamber 11.

[0036] The porosity of the cathode distribution layer 110 is greater than that of the anode distribution layer 120, so that the diffusion rate of alkali and hydrogen in the cathode chamber 11 is greater than that of alkali and oxygen in the anode chamber 12, thereby reducing the accumulation of hydrogen in the cathode chamber 11 and helping to maintain the pressure balance between the cathode chamber 11 and the anode chamber 12.

[0037] The asymmetric electrolyzer provided in this embodiment has a cathode chamber 11 with a larger size than the anode chamber 12 to accommodate an electrolysis condition where the hydrogen yield is greater than the oxygen yield. The pore size of the hydrogen channel 116 is larger than that of the oxygen channel 126 to increase the hydrogen discharge rate. The electrolyzed alkaline solution and hydrogen are discharged together from the hydrogen outlet in the cathode chamber 11. The electrolyzed alkaline solution carries some hydrogen; increasing the pore size of the hydrogen-side alkaline solution channel 115 provides sufficient space for hydrogen evolution in the circulating alkaline solution within the cathode chamber 11. The porosity of the cathode distribution layer 110 is greater than that of the anode distribution layer 120, so that the diffusion rate of alkaline solution and hydrogen in the cathode chamber 11 is greater than that in the anode chamber 12. By setting the cathode chamber 11 and its internal structure, as well as the anode chamber 12 and its internal structure in the above-mentioned asymmetric manner, the discharge rate of hydrogen in the cathode chamber 11 is accelerated, and the average pressure in the cathode chamber 11 is reduced. This is to adapt to the electrolysis condition where the hydrogen production is greater than the oxygen production, and to maintain the pressure balance between the cathode chamber 11 and the anode chamber 12 from inside the electrolysis chamber 1, so as to achieve rapid adjustment of the pressure in the electrolytic cell and effectively avoid the mutual transfer of oxygen and hydrogen.

[0038] As an optional embodiment, the anode distribution layer 120 includes an anode flow field layer 121, an anode redistribution layer 123, and an anode microporous layer 124 stacked sequentially. The cathode distribution layer 110 includes a cathode flow field layer 111, a cathode redistribution layer 113, and a cathode microporous layer 114 stacked sequentially. The aperture of the cathode flow field holes 112 on the cathode flow field layer 111 is larger than that of the anode flow field holes 122 on the anode flow field layer 121, so that the diffusion rate of hydrogen and alkali in the cathode flow field layer 111 is greater than that of oxygen and alkali in the anode flow field layer 121. The aperture of the cathode redistribution holes on the cathode redistribution layer 113 is larger than that of the anode redistribution holes on the anode redistribution layer 123, so that the diffusion rate of hydrogen and alkali in the cathode redistribution layer 113 is greater than that of oxygen and alkali in the anode redistribution layer 123. The diameter of the cathode micropores on the cathode micropore layer 114 is larger than the diameter of the anode micropores on the anode micropore layer 124, so that the diffusion rate of hydrogen and alkali on the cathode micropore layer 114 is greater than the diffusion rate of oxygen and alkali on the anode micropore layer 124.

[0039] As an optional embodiment, the asymmetric electrolyzer further includes a first bipolar plate 117 attached to one side of the cathode distribution layer 110 and a second bipolar plate 127 attached to one side of the anode distribution layer 120. The hydrogen-side alkali channel 115 passes through the first bipolar plate 117 in a straight line and connects to the cathode flow field layer 111. The hydrogen-side alkali channel 115 passes through the second bipolar plate 127 in a straight line and connects to the anode flow field layer 121. Please refer to... Figure 1 The aperture value of the hydrogen-side alkali channel 115 in the first bipolar plate 117 is kept constant, and the alkali is directly supplied to the cathode distribution layer 110 by passing through the first bipolar plate 117, which helps to shorten the path and increase stability. Similarly, the aperture value of the hydrogen-side alkali channel 115 in the second bipolar plate 127 is kept constant, and the alkali is directly supplied to the anode distribution layer 120 by passing through the second bipolar plate 127, which helps to shorten the path and ensures stability and reliability.

[0040] As an optional embodiment, the cathode flow field hole 112 is a through hole connecting the first bipolar plate 117 and the cathode redistribution layer 113, and the anode flow field hole 122 is a bent hole connecting the second bipolar plate 127 and the anode redistribution layer 123, wherein the bent hole is bent along the direction from inlet to outlet. The through hole has better flowability than the bent hole, and hydrogen and alkali move linearly in the through hole so that the diffusion rate of hydrogen and alkali in the cathode flow field layer 111 is greater than the diffusion rate of oxygen and alkali in the anode flow field layer 121 as they move in a bent manner through the bent hole.

[0041] As an optional embodiment, the porosity of the cathode microporous layer 114 is greater than that of the anode microporous layer 124. In this embodiment, the porosity of the cathode microporous layer 114 can be between 50% and 60%, preferably 60%. The porosity of the anode microporous layer 124 can be between 30% and 40%, preferably 40%. By setting the porosity of the cathode microporous layer 114 to be greater than that of the anode microporous layer 124, the diffusion rate of hydrogen and alkaline solution in the cathode flow field layer 111 is greater than the diffusion rate of oxygen and alkaline solution in the anode flow field layer 121.

[0042] As an optional embodiment, the thickness of the cathode distribution layer 110 is twice the thickness of the anode distribution layer 120. To accommodate the situation where the hydrogen production on the cathode chamber 11 side is twice the oxygen production on the anode chamber 12 side, this application sets the thickness of the cathode distribution layer 110 to be twice the thickness of the anode distribution layer 120, which can precisely maintain the pressure balance on both sides.

[0043] As an optional embodiment, the aperture size of the hydrogen-side alkaline channel 115 is twice that of the oxygen-side alkaline channel 125, to accommodate the situation where the hydrogen production on the cathode chamber 11 side is twice that on the anode chamber 12 side, thereby precisely maintaining the pressure balance on both sides.

[0044] As an optional embodiment, the aperture size of the hydrogen channel 116 is twice that of the oxygen channel 126 to accommodate the situation where the hydrogen production on the cathode chamber 11 side is twice that on the anode chamber 12 side, so as to accurately maintain the pressure balance on both sides.

[0045] As an optional embodiment, a first catalyst layer 13 is provided between the diaphragm 10 and the cathode microporous layer 114, and a second catalyst layer 14 is provided between the diaphragm 10 and the anode microporous layer 124. In this embodiment, the first catalyst layer 13 and the second catalyst layer 14 can perform electron transfer functions in the reaction, effectively improving the electrolysis efficiency of the cathode and anode, respectively. The catalyst component of the first catalyst layer 13 can be a platinum catalyst. The catalyst component of the second catalyst layer 14 can be an IrO2 (iridium oxide) catalyst.

[0046] As an optional embodiment, the asymmetric electrolytic cell further includes a first pressure plate portion 2 and a second pressure plate portion 3, with a plurality of electrolytic cells 1 arranged sequentially between the first pressure plate portion 2 and the second pressure plate portion 3. The plurality of electrolytic cells 1 are connected in series to increase the output of the asymmetric electrolytic cell.

[0047] The first pressure plate portion 2 includes a first end pressure plate 20, a first insulating plate 21, and a first power-collecting plate 22 that are sequentially bonded together. The first power-collecting plate 22 is bonded and connected to the first bipolar plate 117. The hydrogen-side alkaline solution channel 115 passes through the first end pressure plate 20, the first insulating plate 21, the first power-collecting plate 22, and the first bipolar plate 117 in sequence. The second pressure plate portion 3 includes a second end pressure plate 30, a second insulating plate 31, and a second power-collecting plate 32 that are sequentially bonded together. The second power-collecting plate 32 is bonded and connected to the second bipolar plate 127. The oxygen-side alkaline solution channel 125 passes through the first end pressure plate 20, the first insulating plate 21, the first power-collecting plate 22, and the first bipolar plate 127 in sequence. In this embodiment, both the hydrogen-side alkaline channel 115 and the oxygen-side alkaline channel 125 extend to the outside of the first pressure plate portion 2 and the second pressure plate portion 3, so as to facilitate subsequent testing of the sealing performance of the cathode chamber 11 and the anode chamber 12 by controlling the opening and closing of the hydrogen-side alkaline channel 115 and the oxygen-side alkaline channel 125 respectively.

[0048] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0049] The above are merely the principles and preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several other modifications can be made based on the principles of the present invention, and these modifications should also be considered within the scope of protection of the present invention.

Claims

1. An asymmetric electrolytic cell, characterized in that, include: An electrolysis chamber includes a diaphragm, a cathode chamber and an anode chamber located on opposite sides of the diaphragm, wherein a cathode distribution layer is provided in the cathode chamber and an anode distribution layer is provided in the anode chamber; The cathode chamber is provided with a hydrogen-side alkaline solution channel for circulating supply of alkaline solution and a hydrogen channel for discharging hydrogen gas; the anode chamber is provided with an oxygen-side alkaline solution channel for circulating supply of alkaline solution and an oxygen channel for discharging oxygen gas. The size of the cathode chamber is larger than that of the anode chamber, the pore size of the hydrogen channel is larger than that of the oxygen channel, the pore size of the hydrogen-side alkaline solution channel is larger than that of the oxygen-side alkaline solution channel, and the porosity of the cathode distribution layer is larger than that of the anode distribution layer. The cathode distribution layer comprises a cathode flow field layer, a cathode redistribution layer, and a cathode micropore layer stacked sequentially. The anode distribution layer comprises an anode flow field layer, an anode redistribution layer, and an anode micropore layer stacked sequentially. The aperture of the cathode flow field hole on the cathode flow field layer is larger than that of the anode flow field hole on the anode flow field layer; The diameter of the cathode redistribution hole on the cathode redistribution layer is larger than that of the anode redistribution hole on the anode redistribution layer; The diameter of the cathode micropores on the cathode micropore layer is larger than the diameter of the anode micropores on the anode micropore layer.

2. The asymmetric electrolytic cell according to claim 1, characterized in that, The asymmetric electrolytic cell also includes a first bipolar plate attached to one side of the cathode distribution layer and a second bipolar plate attached to one side of the anode distribution layer; The hydrogen-side alkaline solution channel passes through the first bipolar plate in a straight line and is connected to the cathode flow field layer. The oxygen-side alkaline solution channel passes through the second bipolar plate in a straight line and is connected to the anode flow field layer.

3. The asymmetric electrolytic cell according to claim 2, characterized in that, The cathode flow field hole is a through hole connecting the first bipolar plate and the cathode redistribution layer, and the anode flow field hole is a bent hole connecting the second bipolar plate and the anode redistribution layer.

4. The asymmetric electrolytic cell according to claim 1, characterized in that, The porosity of the cathode microporous layer is greater than that of the anode microporous layer.

5. The asymmetric electrolytic cell according to any one of claims 1-4, characterized in that, The thickness of the cathode distribution layer is twice the thickness of the anode distribution layer.

6. The asymmetric electrolytic cell according to any one of claims 1-4, characterized in that, The aperture size of the hydrogen-side alkaline solution channel is twice that of the oxygen-side alkaline solution channel.

7. The asymmetric electrolytic cell according to any one of claims 1-4, characterized in that, The aperture size of the hydrogen channel is twice that of the oxygen channel.

8. The asymmetric electrolytic cell according to any one of claims 1-4, characterized in that, A first catalyst layer is provided between the diaphragm and the cathode microporous layer, and a second catalyst layer is provided between the diaphragm and the anode microporous layer.

9. The asymmetric electrolytic cell according to claim 1, characterized in that, The asymmetric electrolytic cell further includes a first pressure plate section and a second pressure plate section, and a plurality of electrolytic chambers are arranged sequentially between the first pressure plate section and the second pressure plate section; The first pressure plate includes a first end pressure plate, a first insulating plate, and a first power-collecting plate that are sequentially attached to each other; The second pressure plate includes a second end pressure plate, a second insulating plate, and a second power-collecting plate that are sequentially attached to each other.

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