A capacitor electrode and a square electrolyzer for decoupling water electrolysis and hydrogen production

Abstract

The present invention relates to the technical field of hydrogen production, and specifically to a capacitor electrode and a square electrolyzer for decoupled water electrolysis to produce hydrogen. By designing a gas and liquid flow channel of the capacitor electrode and the square electrolyzer for decoupled water electrolysis to produce hydrogen, the present invention can achieve isolation of hydrogen and oxygen in the water electrolysis reaction, thereby saving the high cost of ion exchange membranes and breaking through the limitations of diaphragms, so that the working pressure of the electrolyzer can reach 5 MPa or even higher. By providing an electrolyzer limiting mechanism, the electrolysis chamber can be prevented from falling, thereby preventing leakage of the electrolyte. At the same time, the modular skid-mounted design is convenient for decentralized movement and installation and convenient for inspection and maintenance in the event of a fault. By designing a unique square flow field, a square alkali solution inlet and outlet, and a square hydrogen / oxygen outlet, the present invention can ensure uniform flow rate of the electrolyte flow channel and timely discharge of gas, thereby reducing energy loss and improving electrolysis efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production, and in particular to a capacitor electrode and a square electrolytic cell for hydrogen production by decoupling water electrolysis. Background Art

[0002] Currently, alkaline water electrolysis (AWE) is the most mature water electrolysis hydrogen production technology on the market. In the alkaline water electrolysis method, the oxygen evolution reaction (HER) and hydrogen evolution reaction (OER) occurring at the anode and cathode are coupled in time and space. It relies on a diaphragm to separate the hydrogen evolution chamber and the oxygen evolution chamber. The main structural shapes are circular and square, with circular being the most common.

[0003] In recent years, researchers have reported a decoupled water electrolysis scheme that replaces the traditional alkaline electrolyzer diaphragm by introducing a soluble or solid redox medium to achieve decoupled water electrolysis operation. This scheme couples the reduction reaction on the medium with the OER occurring in water electrolysis to produce hydrogen (OER step), and couples the oxidation reaction on the medium with the OER occurring in water electrolysis to produce hydrogen (HER step), thereby achieving temporal or spatial independence of HER and OER in water electrolysis to produce hydrogen.

[0004] Chinese Publication No. CN111074291A discloses a two-step water electrolysis hydrogen production device and method. The high and low temperature electrolytes must be switched between the two steps, making the operation more cumbersome. Furthermore, the high-temperature chemical oxygen production takes a long time, making it difficult to meet the needs of high current density hydrogen production. Chinese Publication No. CN105420748A also discloses a two-step water electrolysis hydrogen production device and method. However, it cannot produce hydrogen and oxygen simultaneously, affecting production efficiency. Meanwhile, in recent years, major manufacturers have gradually introduced square-structured electrolyzers. Chinese Patent Nos. CN 116445942 A, CN 116463657 A, CN 118048640 B, and CN118028847 A also disclose square electrolyzer devices.

[0005] In summary, in practical applications, conventional alkaline water electrolysis to produce hydrogen mainly has the following problems:

[0006] During the hydrogen production process, the volume of hydrogen produced at the cathode is twice the volume of oxygen produced at the anode, resulting in a pressure imbalance on both sides of the diaphragm, which will accelerate the mutual penetration of hydrogen and oxygen. Especially at low current density, the amount of gas produced in the hydrogen evolution chamber and the oxygen evolution chamber is insufficient and the bubbles are small, making it easier for hydrogen and oxygen to penetrate the diaphragm and cross-diffusion to occur. This is also a major drawback of the currently commercialized diaphragms.

[0007] The uneven flow rate of the electrolyte in the electrolytic cell will lead to uneven temperature in the electrolytic cell. At the same time, the hydrogen / oxygen produced by electrolysis cannot be discharged smoothly, which can easily cause perforation of the diaphragm and mechanical damage. When the input power fluctuates, the reaction time of the electrolytic cell is longer, and the electrolysis energy efficiency is low under low load conditions.

[0008] Due to principle and material limitations, the current working pressure of square electrolyzers is mostly normal pressure. In terminal application scenarios, this will increase the comprehensive energy consumption of gas compression and the investment cost of compressors and other equipment.

[0009] Due to the lack of support, the traditional square electrolytic cell has the problem that the electrolysis chamber (the smallest unit for water electrolysis to generate hydrogen and oxygen, composed of cathode and anode electrodes, diaphragm and alkali solution) is prone to falling and causing alkali solution leakage. Summary of the Invention

[0010] In view of this, the object of the present invention is to provide a capacitor electrode and a decoupled electrolysis water hydrogen production square electrolyzer, the capacitor electrode can effectively prevent the mixing of hydrogen and oxygen, the decoupled electrolysis water hydrogen production square electrolyzer can prevent the electrolysis chamber from falling, and through the flow channel design, the decoupled electrolysis water hydrogen production square electrolyzer of the present invention can ensure the uniform flow rate of the electrolyte flow channel and the timely discharge of gas. By cooperating with the capacitor electrode of the present invention, the working pressure of the decoupled electrolysis water hydrogen production square electrolyzer of the present invention can exceed 5MPa.

[0011] To achieve the above objectives, the present invention provides the following technical solutions: a capacitor electrode having a layered structure, which is formed by pressing two side electrode layers and a middle electrode sandwich, wherein the middle electrode sandwich is made of a rigid, microporous, conductive material, and the two side electrode layers are made of a three-dimensional porous conductive material, a conductive agent, and an adhesive; in electrolysis applications, the capacitor electrode is not connected to electricity and does not undergo redox reactions. It allows ions and electrons to pass through and blocks hydrogen and oxygen molecules from passing through. The operating pressure of the electrolytic cell can be greater than 5MPa.

[0012] In particular, the three-dimensional porous conductive material at least includes graphene sol, carbon nanotube sol, porous carbon, and a conductive polymer film.

[0013] Particularly, the capacitor electrode has a thickness of 100 μm to 10 mm.

[0014] At the same time, the present invention also provides a square electrolytic cell for decoupling water electrolysis and hydrogen production, including end plates, polar plates, bipolar plates, insulating gaskets, oxygen evolution electrodes, diaphragms, capacitor electrodes, hydrogen evolution electrodes, limiting support rods, and compression screws.

[0015] The end plates are arranged at both ends of the electrolytic cell, and polar plates are respectively arranged on opposite sides of the end plates, and the polar plates are provided with connection terminals, and at least one bipolar plate is arranged between the left and right polar plates;

[0016] There are mounting grooves inside the electrode plates and bipolar plates. After installation, the mounting grooves between the electrode plates and bipolar plates or between the bipolar plates will form a closed installation space. Insulating gaskets, oxygen evolution electrodes, diaphragms, capacitor electrodes, diaphragms, and hydrogen evolution electrodes are installed in the installation space. The insulating gaskets have the same profile as the electrode plates and bipolar plates and are used to seal the installation space formed by the mounting grooves.

[0017] The end plates are provided with through holes for installing limiting support rods and compression screws, so as to realize compression of all components (polar plate (2), bipolar plate (3), insulating gasket (4), oxygen evolution electrode (5), diaphragm (6), capacitor electrode (7) and hydrogen evolution electrode (8)) between the two end plates.

[0018] Furthermore, an electrode support is provided in the mounting groove for supporting the oxygen evolution electrode and the hydrogen evolution electrode to form an oxygen evolution and hydrogen evolution space.

[0019] In particular, the electrode plates and bipolar plates are provided with upper limit supports and lower limit supports, which cooperate with the limit support rods to prevent the electrode plates, bipolar plates and their internal components (electrolysis chamber) from falling.

[0020] In particular, the electrode plates and bipolar plates are respectively provided with hydrogen channels, cathode alkaline liquid channels, oxygen channels, and anode alkaline liquid channels, wherein the hydrogen channels and cathode alkaline liquid channels are connected to the mounting grooves on one side of the electrode plates and bipolar plates, and the oxygen channels and anode alkaline liquid channels are connected to the mounting grooves on the other side of the electrode plates and bipolar plates;

[0021] After coordinated installation, all hydrogen channels are connected to the corresponding hydrogen outlets on the end plates to form hydrogen circulation channels; all oxygen channels are connected to the corresponding oxygen outlets on the end plates to form oxygen circulation channels; all cathode alkali liquid channels are connected to the corresponding cathode alkali liquid ports on the end plates to form cathode alkali liquid circulation channels; all anode alkali liquid channels are connected to the corresponding anode alkali liquid ports on the end plates to form anode alkali liquid circulation channels.

[0022] In particular, the capacitor electrode can prevent the mixing of oxygen evolved by the oxygen evolution electrode and hydrogen evolved by the hydrogen evolution electrode.

[0023] In particular, the upper limit support and the lower limit support are made of insulating engineering plastic.

[0024] Particularly, the hydrogen channel, cathode alkali solution channel, oxygen channel, and anode alkali solution channel are all square holes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention proposes a capacitor electrode that can block the mixing of H2 and O2, significantly reducing the risk of gas permeation and mixing, while avoiding the use of expensive and difficult-to-maintain ion exchange membranes. In addition, it breaks through the limitations of the diaphragm, allowing the working pressure of the electrolyzer to reach 5MPa or even higher, greatly reducing the comprehensive energy consumption of gas compression and the investment cost of compressors and other equipment.

[0027] The unique square flow field design, square alkali solution inlet and outlet, and square hydrogen / oxygen outlet of the electrolytic cell ensure uniform flow rate of the electrolyte flow channel and timely discharge of gas, making the alkali solution temperature more evenly distributed, reducing energy loss and improving electrolysis efficiency.

[0028] By designing limit supports and flexible screw installation methods, the electrolytic cell chambers can be prevented from falling. At the same time, the modular skid-mounted design facilitates decentralized movement and installation, reducing installation difficulty. The number of chambers can be increased or decreased according to different usage scenarios. When a chamber fails, inspection and maintenance are also more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the square electrolytic cell structure for decoupling water electrolysis and hydrogen production in the present invention Figure 1 ;

[0030] Figure 2 Schematic diagram of the square electrolytic cell structure for decoupling water electrolysis and hydrogen production in the present invention Figure 2 ;

[0031] Figure 3 This is a front view of the electrode plate of the present invention;

[0032] Figure 4 This is a rear view of the electrode plate of the present invention;

[0033] Figure 5 This is a front view of the bipolar plate of the present invention;

[0034] Figure 6 Schematic diagram of the capacitor electrode structure of the present invention;

[0035] Figure 7 This is a schematic diagram of a process application of the present invention.

[0036] In the figure: 1. end plate; 2. polar plate; 3. bipolar plate; 4. insulating gasket; 5. oxygen evolution electrode; 6. diaphragm; 7. capacitor electrode; 701. electrode layer; 702. electrode interlayer; 8. hydrogen evolution electrode; 9. limit support rod; 10. pressing screw; 11. oxygen outlet; 12. anode alkali liquid outlet; 13. hydrogen outlet; 14. cathode alkali liquid outlet; 15. terminal; 16. upper limit support; 17. lower limit support; 18. hydrogen channel; 19. cathode alkali liquid channel; 20. electrode support; 21. mounting groove; 22. oxygen channel; 23. anode alkali liquid channel

[0037] 101. Constant current regulated power supply; 102. Electrolyzer; 103. Hydrogen gas-liquid separation and droplet catching device; 104. Oxygen gas-liquid separation and droplet catching device; 105. Water pump; 106. Pure water tank; 107. Alkali liquid tank; 108. Heat exchanger; 109. Alkali liquid circulation pump. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0039] like Figure 1 、 2 As shown, the present invention provides a square electrolytic cell 102 for decoupling water electrolysis to produce hydrogen. The electrolytic cell 102 uses a capacitor electrode 7 proposed by the present invention. The capacitor electrode 7 is a layered structure, such as Figure 6 As shown, a microporous, conductive, rigid electrode interlayer 702 is provided in the middle to prevent hydrogen and oxygen from mixing. The capacitor electrode 7 is flanked by electrode layers 701, which are formed by pressing a three-dimensional porous conductive material with a conductive agent and an adhesive. The three-dimensional porous conductive material includes but is not limited to graphene sol, carbon nanotube sol, porous carbon, conductive polymer film, and composite film. The thickness of the capacitor electrode 7 is 100 microns to 10 mm.

[0040] In terms of structural composition, in the decoupled electrolysis water hydrogen production square electrolyzer 102 of the present invention, the electrode plate 2 and the adjacent bipolar plate 3 or the bipolar plate 3 and another adjacent bipolar plate 3 form an electrolysis chamber, and mounting grooves 21 are respectively opened on both sides of the electrode plate 2 and the bipolar plate 3, and electrode supports 20 are arranged in the grooves. After installation, a closed space can be formed, and an insulating gasket 4, an oxygen evolution electrode 5, a diaphragm 6, a capacitor electrode 7, a diaphragm 6, and a hydrogen evolution electrode 8 are sequentially installed in the closed space. Accordingly, a space for the electrolytic redox reaction of the electrolyzed water is formed, wherein the hydrogen evolution reaction occurs on one side and the oxygen evolution reaction occurs on the other side with the capacitor electrode 7 as the boundary. In terms of overall composition, the square electrolytic cell 102 for decoupled water electrolysis and hydrogen production of the present invention is provided with end plates 1 on both sides, with a plate 2 installed on each inner side of the end plates 1, and electrolysis chambers installed between the plates 2. The number of electrolysis chambers can be flexibly set. When there are at least a few electrolysis chambers, the end plates 1, plate 2, electrolysis chamber internal components, bipolar plate 3, electrolysis chamber internal components, plate 2, and end plate 1 are installed in sequence from left to right. The electrolysis chamber internal components are, in sequence, insulating gasket 4, oxygen evolution electrode 5, diaphragm 6, capacitor electrode 7, diaphragm 6, and hydrogen evolution electrode 8. When the number of electrolysis chambers needs to be increased, the bipolar plate 3 and the electrolysis chamber internal components are added in sequence at the front end of the rightmost plate 2.

[0041] The structure of the plate 2 is as follows Figure 3 、 Figure 4 As shown, the electrode plate 2 is provided with a terminal 15 for connecting to the electrolytic reaction. The upper and lower ends of each side of the electrode plate 2 are provided with square openings, the upper opening is a gas passage opening, and the lower opening is a liquid passage opening. Figure 3 As shown, the viewing surface of the electrode plate 2 is provided with a square liquid channel opening in the lower left corner and a square gas channel opening in the upper right corner. The liquid channel opening and the gas channel opening are connected to the mounting groove 21 of this side. Therefore, when an electrolytic reaction (such as a reduction reaction) occurs on this side, the gas (hydrogen) flows out from the upper gas channel opening and the liquid (cathode alkali solution) flows out from the lower liquid channel opening. The corresponding other side has a similar structure. When the other polar reaction (oxidation reaction) in the electrolytic reaction occurs, the generated gas (oxygen) flows out from the upper gas channel opening and the liquid (anode alkali solution) flows out from the lower liquid channel opening. Accordingly, the bipolar plate 3 has a similar structure to the electrode plate 2 (without the terminal 15), as shown in FIG. Figure 5As shown. Due to their similar structures, the electrode plate 2 and the bipolar plate 3, when assembled and connected, all upper left channel openings in the same direction are connected to form a gas channel, and the right channel openings are connected to form another gas channel. All lower left channel openings are connected to form a liquid channel, and the right channel openings are connected to form another liquid channel. Among them, the side of the electrode plate 2 or bipolar plate 3 that is in communication with the hydrogen evolution electrode 8 undergoes a reduction reaction, and the corresponding gas channel opening is the hydrogen channel 18, and the liquid channel opening is the cathode alkaline solution channel 19. The side of the electrode plate 2 or bipolar plate 3 that is in communication with the oxygen evolution electrode 5 undergoes an oxidation reaction, and the corresponding gas channel opening is the oxygen channel 22, and the liquid channel opening is the anode alkaline solution channel 23.

[0042] Finally, the hydrogen channel 18 is connected to the hydrogen outlet 13 on the end plate 1, and hydrogen is released and collected. The oxygen channel 22 is connected to the oxygen outlet 11 on the end plate 1, and oxygen is released and collected. The cathode alkali liquid channel 19 is connected to the cathode alkali liquid port 14 on the end plate 1, and the cathode alkali liquid is circulated. The anode alkali liquid channel 23 is connected to the anode alkali liquid port 12 on the end plate 1, and the anode alkali liquid is circulated.

[0043] In summary, using the decoupled electrolysis water hydrogen production square electrolyzer 102 of the present invention, hydrogen and oxygen can flow out from different channels respectively, and the alkaline solutions at the cathode and anode are also circulated separately. In addition, the capacitor electrode 7 of the present invention can block the passage of hydrogen and oxygen molecules, thereby achieving the decoupling of the hydrogen evolution reaction and the oxygen evolution reaction, which not only saves the high cost of using ion exchange membranes, but also greatly reduces the risk of gas permeation and mixing. Moreover, since the limitation of the diaphragm is broken through, the working pressure of the electrolyzer 102 can be 5 MPa or even higher, which greatly reduces the comprehensive energy consumption such as gas compression and the investment cost of compressors and other equipment. On the other hand, the unique flow field design of the electrolytic cell 102 of the present invention ensures uniform flow velocity of the electrolyte flow channel and timely discharge of gas, more uniform temperature distribution of the alkali solution, reduced energy loss, and improved electrolysis efficiency. In addition, the electrodes (including the oxygen evolution electrode 5 and the hydrogen evolution electrode 8) and the diaphragm 6 of the electrolytic cell 102 are all square structures, and no cutting is required during use, which saves costs and materials (generally, the electrodes and diaphragms 6 produced are mostly square. If a traditional circular electrolytic cell structure is used, the electrodes and diaphragms 6 need to be cut). Example 2

[0044] like Figure 3 、 4As shown in Figures 5 and 6, the electrode plate 2 and the bipolar plate 3 are respectively provided with an upper limit support 16 and a lower limit support 17. When the entire electrolytic cell 102 assembly is arranged in sequence and compressed by the compression screw 10, the upper limit support 16 and the lower limit support 17 on the electrode plate 2 and the bipolar plate 3 are respectively stuck on the limit support rod 9, thereby preventing the electrolytic chamber from falling and thus preventing the leakage of the alkali solution. In addition, since the electrolytic cell 102 of the present invention adopts a modular skid-mounted design, it can be easily moved and installed in a decentralized manner, reducing the difficulty of installation, and the number of chambers can be increased or decreased according to different usage scenarios. When a chamber fails, inspection and maintenance are also more convenient.

[0045] It should be noted that the present invention simplifies the composition to clearly express the main structure. Figure 1 、 Figure 2 The middle compression screw 10 is not fully drawn. In actual application, the position where the nut is drawn on the end plate 1 is provided with a compression screw 10 to achieve compression of the electrolytic cell 102. Example 3

[0046] like Figure 7 The figure shows a schematic diagram of a process application of the present invention. During the production process, a constant current regulated power supply 101 provides electrolysis energy, and the electrolytic cell 102 uses a KOH solution with an alkali concentration of 27% to 32%. The hydrogen and oxygen generated therein enter the gas-liquid separation and dripping device through different flow channels respectively, and are collected after purification. The alkali liquid in the hydrogen gas-liquid separation and dripping device 103 and the oxygen gas-liquid separation and dripping device 104 is cooled by the heat exchanger 108 and then pumped out to the electrolytic cell 102 by the alkali liquid circulation pump 109, thereby realizing the alkali liquid cooling cycle and maintaining the alkali liquid temperature in the electrolytic cell 102. At the same time, this process is provided with an alkali liquid tank 107, an alkali liquid circulation pump 109, a pure water tank 106 and a water pump 105 to replenish the alkali liquid and pure water in time.

[0047] In terms of materials, the electrode material of the hydrogen evolution electrode 8 can be a composite of precious metals Pt, Pd and carbon materials, or a single substance or compound based on transition metals Ni, Co, Cu or Fe, or a compound based on rare earth elements W and Mo; the electrode material of the oxygen evolution electrode 5 can be a composite of precious metals Ru, Ir and carbon materials, or a single substance or compound based on transition metals Ni, Co, Cu or Fe.

[0048] When the circuit is connected, water molecules are reduced to hydrogen gas on the hydrogen evolution electrode 8, i.e. 2H2O + e - → H2+2OH - OH - Driven by the external electric field, the capacitor electrode 7 itself is positively charged, which will promote OH - Migrate to the anode, OH - It is oxidized to oxygen on the oxygen evolution electrode 5, namely 2OH- → 1 / 2O2 + H2O + e - .

[0049] The capacitor electrode 7 itself does not undergo redox reaction and is not connected to electricity. Ions and electrons can be transferred to the hydrogen evolution electrode 8 and the oxygen evolution electrode 5 through the capacitor electrode 7 .

[0050] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A square electrolytic cell for decoupled water electrolysis and hydrogen production, comprising an end plate (1), a polar plate (2), a bipolar plate (3), an insulating gasket (4), an oxygen evolution electrode (5), a diaphragm (6), a capacitor electrode (7), a hydrogen evolution electrode (8), a limiting support rod (9), and a pressing screw (10), characterized in that: The end plates (1) are arranged at both ends, and polar plates (2) are respectively arranged on opposite sides of the end plates (1). The polar plates (2) are provided with connection terminals (15). At least one bipolar plate (3) is arranged between the left and right polar plates (2); the polar plates (2) and the bipolar plates (3) have mounting grooves (21) inside. After being mounted together, the mounting grooves (21) between the polar plates (2) and the bipolar plates (3) or between the bipolar plates (3) and the bipolar plates (3) form a closed mounting space. An insulating gasket (4), an oxygen evolution electrode (5), a diaphragm (6), a capacitor electrode (7), a diaphragm (6), and a hydrogen evolution electrode (8) are sequentially mounted in the mounting space. The insulating gasket (4) has the same profile as the polar plates (2) and the bipolar plates (3) and is used to seal the mounting space formed by the mounting grooves (21); the end plates (1) is provided with a through hole for installing a limiting support rod (9) and a pressing screw (10) to realize the compression of the electrode plate (2), bipolar plate (3), insulating gasket (4), oxygen evolution electrode (5), diaphragm (6), capacitor electrode (7) and hydrogen evolution electrode (8) between the two end plates (1), wherein the capacitor electrode (7) is a layered structure, which is formed by pressing the two side electrode layers (701) and the middle electrode sandwich (702), wherein the middle electrode sandwich (702) is a rigid, microporous, conductive material, and the two side electrode layers (701) are made of a three-dimensional porous conductive material, a conductive agent, and an adhesive; in electrolysis applications, the capacitor electrode (7) is not connected to electricity and does not undergo redox reaction, and allows ions and electrons to pass through and blocks hydrogen and oxygen molecules from passing through; The three-dimensional porous conductive material at least includes graphene sol, carbon nanotube sol, porous carbon, and conductive polymer film; The thickness of the capacitor electrode (7) is: 100 μm~10 mm; An electrode support (20) is provided in the mounting groove (21) for supporting the oxygen evolution electrode (5) and the hydrogen evolution electrode (8) to form oxygen evolution and hydrogen evolution spaces; An upper limit support (16) and a lower limit support (17) are provided on the electrode plate (2) and the bipolar plate (3). The upper limit support (16) and the lower limit support (17) cooperate with the limit support rod (9) to prevent the electrode plate (2), the bipolar plate (3) and their internal components from falling.

2. The square electrolytic cell for decoupled water electrolysis and hydrogen production according to claim 1, characterized in that: The polar plate (2) and the bipolar plate (3) are respectively provided with a hydrogen channel (18), a cathode alkali liquid channel (19), an oxygen channel (22), and an anode alkali liquid channel (23), wherein the hydrogen channel (18) and the cathode alkali liquid channel (19) are connected to the mounting groove (21) on one side of the polar plate (2) and the bipolar plate (3), and the oxygen channel (22) and the anode alkali liquid channel (23) are connected to the mounting groove (21) on the other side of the polar plate (2) and the bipolar plate (3); after being installed, all hydrogen channels are connected. The channels (18) are connected to the corresponding hydrogen outlets (13) on the end plate (1) to form hydrogen circulation channels; all oxygen channels (22) are connected to the corresponding oxygen outlets (11) on the end plate (1) to form oxygen circulation channels; all cathode alkali liquid channels (19) are connected to the corresponding cathode alkali liquid ports (14) on the end plate (1) to form cathode alkali liquid circulation channels; all anode alkali liquid channels (23) are connected to the corresponding anode alkali liquid ports (12) on the end plate (1) to form anode alkali liquid circulation channels.

3. The square electrolytic cell for producing hydrogen by decoupling water electrolysis as claimed in claim 2, characterized in that: The capacitor electrode (7) can prevent the mixing of oxygen gas released by the oxygen evolution electrode (5) and hydrogen gas released by the hydrogen evolution electrode (8).

4. The square electrolytic cell for producing hydrogen by decoupling water electrolysis as claimed in claim 3, characterized in that: The upper limit support (16) and the lower limit support (17) are made of insulating engineering plastics.

5. The square electrolytic cell for producing hydrogen by decoupling water electrolysis as claimed in claim 4, characterized in that: The hydrogen channel (18), cathode alkali solution channel (19), oxygen channel (22), and anode alkali solution channel (23) are all square holes.

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