Electrolytic cell for hydrogen production by electrolysis

Abstract

This invention belongs to the field of hydrogen production technology through water electrolysis, and specifically relates to an electrolytic cell for hydrogen production. It includes a composite electrode assembly; the composite electrode assembly comprises an electrode frame, a bipolar plate, an electrode conductive frame, an oxygen evolution electrode, and a hydrogen evolution electrode. The electrode frame is disposed on the outside of the bipolar plate, and both the electrode frame and the bipolar plate are made of plastic. The electrode conductive frame is disposed inside the electrode frame. The oxygen evolution electrode and the hydrogen evolution electrode are respectively disposed on both sides of the bipolar plate and are connected to the electrode conductive frame. This invention uses a plastic-based bipolar plate, which provides a sealing function, eliminating the need for the sealing gasket components of traditional electrolytic cells and significantly reducing the cost of the electrolytic cell. Integrating the plastic-based bipolar plate with the electrodes and the electrode conductive frame into one unit greatly simplifies the assembly and integration process of the electrolytic cell.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production technology, and specifically relates to an electrolytic cell for hydrogen production. Background Technology

[0002] Hydrogen is not only an ideal clean energy carrier but also an extremely important chemical raw material. Hydrogen produced by electrolyzing water using renewable energy sources is known as "green hydrogen" and represents the future direction of the energy and chemical industries. Hydrogen production technologies through water electrolysis are mainly divided into alkaline water electrolysis (AWE), proton exchange membrane (PEM), and solid oxide electrolysis (SOE). Alkaline water electrolysis is simple in structure, technologically mature, and has low cost, making it the most widely used water electrolysis technology in large-scale hydrogen production.

[0003] like Figure 1-2 As shown, the alkaline water electrolysis hydrogen production device mainly includes an electrolyzer and an auxiliary frame with functions such as gas-liquid separation and purification. The electrolyzer, the core component of the device, is mainly composed of end pressure plates, bipolar plates 2, electrodes, a diaphragm 5, sealing gaskets, and bolts. During operation, the liquid inlet is split into two, entering the reaction chambers on either side of the diaphragm 5. The electrode tank outputs liquid through two channels to gas-liquid separators I15 and II14, thereby producing oxygen and hydrogen. The electrolyte in gas-liquid separators I15 and II14 is collected and recycled back into the electrolyzer. It is estimated that the bipolar plates account for 44% of the manufacturing cost of the electrolyzer, sealing materials 8%, end pressure plates 5%, electrodes 28%, and the diaphragm 8%. The bipolar plates are the key component affecting the manufacturing cost of the electrolyzer. To meet the requirements of high-temperature and strong alkali corrosion, high-pressure alkaline gas-liquid sealing, porous electrode current collection, and electrolyte and gas flow, the bipolar plates of electrolyzers are currently generally made of thin carbon steel plates precision stamped into double-sided protruding plates, which are then welded together with thick carbon steel electrode frames and subjected to overall nickel plating. The difference in thickness between the electrode frame and the bipolar plate is because after the bipolar plate is stamped into double-sided protruding plates, the protrusions occupy a certain thickness space to accommodate electrolyte flow. However, this results in a longer bipolar plate manufacturing process, and the electrode frame and plate need to be processed separately before being welded together, leading to high material / processing costs. This directly increases the cost of alkaline water electrolysis hydrogen production equipment, hindering the large-scale application of alkaline water electrolysis hydrogen production technology. On the other hand, the carbon steel material generally used for bipolar plates has low conductivity. The electrode and the protruding tips of the bipolar plate are electrically connected by pressing, which results in high contact resistance due to pressure and corrosion. This leads to a large voltage drop due to the electrolyzer's resistance, directly increasing the DC power consumption of the alkaline water electrolysis hydrogen production equipment. The increased resistance of the electrolyzer also leads to an increase in heat generation power, further increasing the heat dissipation requirements of the hydrogen production unit. Both of these significant issues increase the manufacturing and operating costs of alkaline water electrolysis hydrogen production units, hindering the larger-scale application of alkaline water electrolysis hydrogen production technology. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide an electrolytic hydrogen production electrolyzer to solve the problem of high manufacturing and usage costs of existing alkaline water electrolysis hydrogen production electrolyzers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides an electrolytic hydrogen production electrolyzer, including a composite electrode assembly;

[0007] The composite electrode assembly includes an electrode frame, a bipolar plate, an electrode conductive frame, an oxygen evolution electrode, and a hydrogen evolution electrode. The electrode frame is located outside the bipolar plate, and both the electrode frame and the bipolar plate are made of plastic. The electrode conductive frame is located inside the electrode frame. The oxygen evolution electrode and the hydrogen evolution electrode are located on both sides of the bipolar plate and are connected to the electrode conductive frame.

[0008] The pole frame, bipolar plate, and electrode conductive frame are all annular. The bipolar plate is circular. The cross-section of the electrode conductive frame is a U-shaped groove structure including the outer edge of the bipolar plate. The inner edge of the electrode conductive frame is exposed on the inner surface of the pole frame and is located on both sides of the bipolar plate.

[0009] The electrode conductive frame is made of carbon steel, stainless steel, nickel-plated carbon steel, or pure nickel plate by stamping and welding; the thickness of the electrode conductive frame is 1-3mm, and the electrode conductive frame is provided with multiple through holes for connecting the electrode frame and the bipolar plate.

[0010] The electrode frame is provided with an inlet and an outlet along the axial direction, and both the inlet and outlet penetrate the electrode conductive frame; the inner surface of the electrode frame is provided with multiple flow channels that are respectively connected to the inlet and outlet along the radial direction.

[0011] The electrode frame, electrode conductive frame and bipolar plate are an integral structure, and the two sides of the electrode frame are provided with annular sealing lines.

[0012] The bipolar plate includes a reaction zone located in the center, and multiple papillae are provided on both sides of the reaction zone; the oxygen evolution electrode and the hydrogen evolution electrode are connected to the electrode conductive frame by welding or by screws.

[0013] The thickness of the bipolar plate is 3-20mm. A porous mesh is provided on both sides of the bipolar plate. The porous mesh is welded to the electrode conductive frame. The oxygen evolution electrode and the hydrogen evolution electrode are respectively attached to the porous mesh on both sides of the bipolar plate.

[0014] The two composite electrode assemblies are stacked with a diaphragm in the middle, forming a hydrogen evolution reaction chamber and an oxygen evolution reaction chamber on both sides of the diaphragm.

[0015] Multiple electrolytic hydrogen production cells are stacked sequentially, and two adjacent electrolytic hydrogen production cells share a bipolar plate; end pressure plates are provided at both ends of the multiple electrolytic hydrogen production cells stacked sequentially, and the multiple electrolytic hydrogen production cells are tightened and fixed by bolts.

[0016] The advantages and beneficial effects of the present invention are as follows: The electrolytic hydrogen production electrolyzer provided by the present invention adopts a plastic-based bipolar plate, which greatly reduces the material and processing costs of the electrode plate; the plastic-based bipolar plate itself can play a sealing role, eliminating the sealing gasket component of the traditional electrolyzer and greatly reducing the cost of the electrolyzer; the plastic-based bipolar plate is integrated with the electrode and the electrode conductive frame, which greatly simplifies the assembly and integration process of the electrolyzer. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a traditional electrolytic cell.

[0018] Figure 2 This is a schematic diagram of the explosion-proof design of a traditional electrolytic cell;

[0019] Figure 3 This is a schematic diagram of the structure of an electrolytic hydrogen production electrolyzer according to the present invention;

[0020] Figure 4 This is an exploded view of an electrolytic hydrogen production electrolyzer according to the present invention;

[0021] Figure 5 This is a schematic diagram of the composite electrode assembly in this invention.

[0022] In the diagram: 1-Electrode frame, 2-Bipolar plate, 3-Seal, 4-Oxygen evolution electrode, 5-Diaphragm, 6-Hydrogen evolution electrode, 7-Inlet, 8-Papillary, 9-Outlet, 10-Annular sealing line, 11-Traditional bipolar plate weld joint, 12-Flow channel, 13-Diaphragm groove, 14-Gas-liquid separator II, 15-Gas-liquid separator I, 16-Electrode conductive frame, 21-Reaction zone. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 3-4As shown, this invention provides an electrolytic hydrogen production electrolyzer, including a composite electrode assembly. The composite electrode assembly includes an electrode frame 1, a bipolar plate 2, an electrode conductive frame 16, an oxygen evolution electrode 4, and a hydrogen evolution electrode 6. The electrode frame 1 is disposed on the outside of the bipolar plate 2. Both the electrode frame 1 and the bipolar plate 2 are made of plastic. The electrode conductive frame 16 is disposed inside the electrode frame 1. The oxygen evolution electrode 4 and the hydrogen evolution electrode 6 are respectively disposed on both sides of the bipolar plate 2 and are both connected to the electrode conductive frame 16. This invention uses a plastic-based bipolar plate, which can provide a sealing function, eliminating the need for the sealing gasket components of traditional electrolyzers and significantly reducing the cost of the electrolyzer.

[0025] like Figure 4 As shown in the embodiment of the present invention, the electrode frame 1, the bipolar plate 2 and the electrode conductive frame 16 are all annular, the bipolar plate 2 is circular, the cross-section of the electrode conductive frame 16 is a U-shaped groove structure including the outer edge of the bipolar plate 2, the inner annular edge of the electrode conductive frame 16 is exposed on the inner surface of the electrode frame 1 and is located on both sides of the bipolar plate 2 so as to connect with the oxygen evolution electrode 4 and the hydrogen evolution electrode 6 on both sides of the bipolar plate 2.

[0026] In embodiments of the present invention, the electrode conductive frame 16 is manufactured by stamping and welding carbon steel, stainless steel, nickel-plated carbon steel, or pure nickel plate; the thickness of the electrode conductive frame 16 is 1-3 mm. Multiple through holes are provided on the electrode conductive frame 16 for connecting the electrode frame 1 and the bipolar plate 2. Specifically, the electrode frame 1, the electrode conductive frame 16, and the bipolar plate 2 are an integral structure, integrating the plastic-based bipolar plate 2 with the electrode and the electrode conductive frame 16 into a single unit, significantly simplifying the assembly and integration process of the electrolytic cell.

[0027] like Figure 5 As shown in the embodiment of the present invention, the pole frame 1 is provided with an inlet 7 and an outlet 9 along the axial direction, and the inner surface of the pole frame 1 is provided with a plurality of flow channels 12 that are respectively connected to the inlet 7 and the outlet 9 along the radial direction. The liquid enters through the inlet 7 and then enters the reaction chamber through the flow channel 12 connected to the inlet 7; or, the liquid in the reaction chamber flows out through the outlet 9 through the flow channel 12 connected to the outlet 9.

[0028] Furthermore, both sides of the pole frame 1 are provided with annular sealing lines 10 to facilitate a sealed connection with the adjacent pole frame 1.

[0029] In one embodiment of the present invention, the bipolar plate 2 includes a reaction zone 21 located in the center, and multiple papillae 8 are provided on both sides of the reaction zone 21. Specifically, the oxygen evolution electrode 4 and the hydrogen evolution electrode 6 are connected to the electrode conductive frame 16 by welding or screws.

[0030] In another embodiment of the present invention, the thickness of the bipolar plate 2 is 3-20mm, and a porous mesh is provided on both sides of the bipolar plate 2. The porous mesh is welded to the electrode conductive frame 16, and the oxygen evolution electrode 4 and the hydrogen evolution electrode 6 are respectively attached to the porous mesh on both sides of the bipolar plate 2, thereby realizing the connection between the oxygen evolution electrode 4 and the hydrogen evolution electrode 6 and the electrode conductive frame 16.

[0031] Specifically, the electrode frame 1 and bipolar plate 2 are made of plastic or fiber-reinforced plastic. The plastics include polyethylene, polypropylene, polyvinyl chloride, ABS, PEEK, PTFE, epoxy resin, etc., while the fiber materials include glass fiber, carbon fiber, boron fiber, etc. The plastic electrode frame 1 and bipolar plate 2 can be integrally molded by injection molding, or manufactured by compression molding, milling, 3D printing, etc. The thickness of the bipolar plate 2 is 3-20 mm, preferably 5-12 mm.

[0032] like Figure 3-4 As shown, in an embodiment of the present invention, two composite electrode assemblies are stacked and a diaphragm 5 is provided in the middle. The diaphragm 5 is housed in a diaphragm groove 13 provided on the corresponding surfaces of the two electrode frames 1, forming a hydrogen evolution reaction chamber and an oxygen evolution reaction chamber on both sides of the diaphragm 5. The oxygen evolution electrode 4 and the hydrogen evolution electrode 6 are respectively housed in the oxygen evolution reaction chamber and the hydrogen evolution reaction chamber on both sides of the diaphragm 5.

[0033] Based on the above embodiments, multiple electrolytic hydrogen production cells are stacked sequentially, and two adjacent electrolytic hydrogen production cells share a composite electrode assembly; end pressure plates are provided at both ends of the multiple electrolytic hydrogen production cells stacked sequentially, and the two end plates are connected by bolts, with the bolts passing through each electrolytic hydrogen production cell, thereby tightening and fixing the multiple electrolytic hydrogen production cells.

[0034] Example 1

[0035] Electrode conductive frames 16 are obtained by laser cutting, stamping, welding, and electroplating nickel from 2mm carbon steel plates. The electrode conductive frames 16 are fixed in an injection mold, and a bipolar plate electrode frame conductive sealing integral part is obtained by injection molding with soluble polytetrafluoroethylene. The hydrogen evolution electrode 6 is a nickel mesh sprayed with Raney nickel, and the oxygen evolution electrode 4 is a nickel mesh. The hydrogen evolution electrode 6 and the oxygen evolution electrode 4 are respectively welded to the electrode conductive frames 16 on both sides of the integral part to obtain a composite electrode assembly. The diaphragm 5 is made of PPS cloth. 40mm thick end pressure plates are used on both sides of the electrolytic cell, stacked in the following order: end pressure plate - composite electrode assembly - diaphragm - composite electrode assembly - diaphragm - composite electrode assembly - end pressure plate. The stacked plates are tightened by screws to obtain a novel gasket-free electrolytic cell with 10 small chambers. Install the electrolytic cell onto the water electrolysis test device. Use 30% KOH solution as the electrolyte. Operating temperature: 90℃. Operating pressure: 0.6MPa. Electrolysis current: 125A. Record the electrolytic cell processing time and electrolytic cell voltage.

[0036] Processing time for electrode conductive frame 16: laser cutting 1 min, stamping 0.5 min, welding 5 min, electroplating 30 min, total time 36.5 min. Electrolytic cell voltage: 18.10V; Electrolytic cell DC power consumption: 4.32kWh / Nm³ 3 H2.

[0037] Example 2

[0038] Electrode conductive frames 16 are obtained by laser cutting, stamping, and welding of 2mm pure nickel plates. These frames are then fixed in an injection mold, and a bipolar plate, electrode frame, and conductive seal are integrally molded using PEEK. The hydrogen evolution electrode 6 is a nickel mesh coated with Raney nickel, and the oxygen evolution electrode 4 is a nickel mesh. The hydrogen evolution electrode 6 and oxygen evolution electrode 4 are respectively fixed to the electrode conductive frames 16 on both sides of the integral component with screws, resulting in a composite electrode assembly. The diaphragm 5 is made of PPS cloth. 40mm thick end plates are used on both sides of the electrolytic cell. The cells are stacked in the following order: end plate - composite electrode assembly - sealing gasket - diaphragm - composite electrode assembly - sealing gasket - diaphragm - composite electrode assembly - end plate, and tightened with screws to obtain a novel electrolytic cell with 10 chambers. The electrolytic cell is installed in a water electrolysis testing device. The electrolyte is a 30% KOH solution, the operating temperature is 90℃, the operating pressure is 0.6MPa, and the electrolysis current is 125A. The processing time and voltage of the electrolytic cell are recorded.

[0039] Processing time for electrode conductive frame 16: laser cutting 1 min, stamping 0.5 min, welding 5 min, total time 6.5 min. Electrolytic cell voltage: 18.20V; Electrolytic cell DC power consumption: 4.35kWh / Nm³ 3 H2.

[0040] Comparative Example

[0041] Bipolar plate 2 is obtained by laser cutting and stamping of 3mm carbon steel plate, and electrode frame 1 is obtained by laser cutting and CNC machining of 5mm carbon steel plate. Bipolar plate 2 and electrode frame 1 are welded together and nickel-plated to obtain a single bipolar plate and electrode frame assembly with a reaction area of ​​500 cm². 2 The sealing component 3 is obtained by CNC machining of a 3mm glass fiber reinforced PTFE sheet. The hydrogen evolution electrode uses a nickel mesh coated with Raney nickel, the oxygen evolution electrode uses a nickel mesh, the diaphragm 5 is made of PPS cloth, and 40mm thick end pressure plates are used on both sides of the electrolytic cell. Figure 1 The cells are stacked in the order shown and tightened by a screw to form a conventional electrolytic cell with 10 chambers. The electrolytic cell is then installed in a water electrolysis test device. The electrolyte is a 30% KOH solution, the operating temperature is 90℃, the operating pressure is 0.6MPa, and the electrolysis current is 125A. The processing time and voltage of the electrolytic cell are recorded.

[0042] Processing time for the integrated bipolar plate and frame: bipolar plate laser cutting 1 min, bipolar plate stamping 0.5 min, frame laser cutting 2 min, frame CNC machining 2 h, welding 30 min, electroplating 30 min, total time 183.5 min. Seal processing time: CNC machining 3 min; Electrolytic cell voltage: 18.18V; Electrolytic cell DC power consumption: 4.35kWh / Nm³ 3 H2.

[0043] It is evident that the traditional bipolar plate frame of an electrolytic cell has a long processing time and high processing cost. The processing time of the new integrated conductive and sealing component of the bipolar plate frame of an electrolytic cell is greatly reduced, which can significantly reduce the processing cost of the electrolytic cell.

[0044] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, extensions, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. An electrolytic cell for hydrogen production, characterized in that, Including composite electrode assemblies; The composite electrode assembly includes an electrode frame (1), a bipolar plate (2), an electrode conductive frame (16), an oxygen evolution electrode (4), and a hydrogen evolution electrode (6). The electrode frame (1) is located on the outside of the bipolar plate (2), and both the electrode frame (1) and the bipolar plate (2) are made of plastic. The electrode conductive frame (16) is located inside the electrode frame (1). The oxygen evolution electrode (4) and the hydrogen evolution electrode (6) are located on both sides of the bipolar plate (2) and are connected to the electrode conductive frame (16). The pole frame (1) and the electrode conductive frame (16) are both annular, the bipolar plate (2) is circular, the cross-section of the electrode conductive frame (16) is a U-shaped groove structure including the outer edge of the bipolar plate (2), and the inner annular edge of the electrode conductive frame (16) is exposed on the inner surface of the pole frame (1) and located on both sides of the bipolar plate (2). The electrode frame (1) is provided with an inlet (7) and an outlet (9) along the axial direction, and the inlet (7) and outlet (9) both penetrate the electrode conductive frame (16); the inner surface of the electrode frame (1) is provided with a plurality of flow channels (12) that are respectively connected to the inlet (7) and outlet (9) along the radial direction. The pole frame (1), the electrode conductive frame (16) and the bipolar plate (2) are an integral structure, and the two sides of the pole frame (1) are provided with annular sealing lines (10). A porous mesh is provided on both sides of the bipolar plate (2), and the porous mesh is welded to the electrode conductive frame (16). The oxygen evolution electrode (4) and the hydrogen evolution electrode (6) are respectively attached to the porous mesh on both sides of the bipolar plate (2).

2. The electrolytic hydrogen production electrolyzer according to claim 1, characterized in that, The electrode conductive frame (16) is made of carbon steel, stainless steel, nickel-plated carbon steel or pure nickel plate by stamping and welding; the thickness of the electrode conductive frame (16) is 1-3mm, and the electrode conductive frame (16) is provided with a plurality of through holes for connecting the electrode frame (1) and the bipolar plate (2).

3. The electrolytic hydrogen production electrolyzer according to claim 1, characterized in that, The bipolar plate (2) includes a reaction zone (21) located in the center, and multiple papillae (8) are provided on both sides of the reaction zone (21).

4. The electrolytic hydrogen production electrolyzer according to claim 3, characterized in that, The oxygen evolution electrode (4) and the hydrogen evolution electrode (6) are connected to the electrode conductive frame (16) by welding or by screws.

5. The electrolytic hydrogen production electrolyzer according to claim 1, characterized in that, The thickness of the bipolar plate (2) is 3-20 mm.

6. The electrolytic hydrogen production electrolyzer according to any one of claims 1-5, characterized in that, The two composite electrode assemblies are stacked and a diaphragm (5) is provided in the middle, forming a hydrogen evolution reaction chamber and an oxygen evolution reaction chamber on both sides of the diaphragm (5).

7. The electrolytic hydrogen production electrolyzer according to claim 6, characterized in that, Multiple electrolytic hydrogen production cells are stacked sequentially, and two adjacent electrolytic hydrogen production cells share a bipolar plate (2); end pressure plates are provided at both ends of the multiple electrolytic hydrogen production cells stacked sequentially, and the multiple electrolytic hydrogen production cells are tightened and fixed by bolts.

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