Large modular hydrogen production electrolytic cell

Abstract

The invention discloses a large-scale modularized hydrogen production electrolytic cell, which comprises an electrode assembly, the electrode assembly comprises a substrate, the substrate is provided with an electrode A and an electrode B, the electrode A and the electrode B are mutually independently powered, the electrode A and the electrode B are alternately powered on, and the alternating frequency is 30-120 Hz; when the electrode assembly works, one of the electrode A and the electrode B is always in a power-on state. According to the large-scale modularized hydrogen production electrolytic cell, the electrode polarization phenomenon can be reduced through high-frequency alternate energization between the electrode A and the electrode B, and therefore the electrolytic efficiency of the electrolyte is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production electrolyzers, and in particular relates to a large modular hydrogen production electrolyzer. Background Art

[0002] Large modular hydrogen production electrolyzer is a device that realizes large-scale hydrogen production through modular design. Its core lies in decomposing the electrolyzer into multiple modules that can operate independently. These modules can be flexibly combined according to actual needs, so as to achieve efficient water electrolysis hydrogen production and meet the production needs of different scales.

[0003] The working principle of large-scale modular hydrogen production electrolyzers is based on the electrolysis of water, that is, decomposing water into hydrogen and oxygen under the action of direct current. The electrolyzer consists of multiple electrolysis chamber modules, each of which includes an anode chamber and a cathode chamber, which are separated by an ion exchange membrane or diaphragm. During the electrolysis process, the water in the anode chamber generates oxygen through the anodic oxidation reaction, while the water in the cathode chamber generates hydrogen through the cathode reduction reaction.

[0004] However, in actual operation, the hydrogen production electrolyzer has the following technical problems during continuous operation:

[0005] ① Electrode polarization phenomenon: Electrode polarization will cause the electrode potential to deviate from its equilibrium potential, thereby increasing the voltage required for electrolysis. In the process of electrolysis of water to produce hydrogen, the theoretical decomposition voltage is 1.23V, but due to the existence of polarization, the actual required voltage will be significantly increased. This additional voltage drop is mainly used to overcome the resistance caused by polarization, rather than directly used for the electrolysis reaction itself, resulting in increased energy consumption and significantly reduced electrolysis efficiency.

[0006] ② Coverage of bubbles on electrodes: During the electrolysis process, bubbles (such as hydrogen and oxygen) will accumulate on the electrode surface to form a bubble layer. These bubbles will hinder the contact between the electrolyte and the electrode surface, increase resistance, and thus reduce electrolysis efficiency. In addition, the accumulation of bubbles may also lead to uneven distribution of local current density, further affecting the stability and efficiency of the electrolyzer.

[0007] ③ Increased electrolytic cell temperature: During continuous operation, the electrodes will generate heat due to the passage of current, causing the electrolytic cell temperature to rise. The increase in temperature will not only increase the energy consumption of the electrolytic cell, but may also cause thermal stress to the internal materials of the electrolytic cell (such as ion exchange membranes, electrode coatings, etc.), affecting their service life and performance stability. At the same time, a high temperature environment may also intensify the occurrence of side reactions, further reducing the electrolysis efficiency. Summary of the invention

[0008] In view of the deficiencies in the prior art, an object of the present invention is to provide a large-scale modular hydrogen production electrolyzer.

[0009] Large-scale modular hydrogen production electrolyzers are operated by combining multiple module units, and the core components of each module unit are the electrode assembly, diaphragm, and electrode assembly stacked in sequence. The electrode assembly is divided into anode electrodes and cathode electrodes, which are respectively arranged on both sides of the diaphragm.

[0010] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0011] The electrode assembly includes a substrate, on which an electrode A and an electrode B are arranged, and the electrode A and the electrode B are powered independently of each other, and the electrode A and the electrode B are powered alternately, and the alternating frequency is 30Hz to 120Hz; when the electrode assembly is working, one of the electrode A and the electrode B is always in a powered state.

[0012] In the present invention, alternating energization of electrode A and electrode B helps to optimize the reaction kinetics on the electrode surface and reduce the overpotential.

[0013] In the present invention, the electrode A and the electrode B are energized alternately in a high-frequency on-off mode to reduce electrode polarization and improve electrolysis efficiency.

[0014] In the present invention, the electrode assembly as a whole can continuously conduct electricity without interruption of power supply. A plurality of electrodes A and a plurality of electrodes B are energized alternately, so that electrodes A and electrodes B have more opportunities to be water-cooled. Compared with the traditional state where electrodes are continuously energized, the temperature is easier to control.

[0015] In the present invention, the pulse current helps to alleviate the concentration polarization and electrochemical polarization on the surfaces of electrode A and electrode B, further improving the reaction rate of producing hydrogen or oxygen.

[0016] In the present invention, the alternating on-off mode of electrode A and electrode B can reduce electrode corrosion and passivation and extend the service life of the electrode assembly.

[0017] Preferably, the electrode A and the electrode B are both strip-shaped and parallel to each other, and the electrode A and the electrode B are both vertically arranged.

[0018] Preferably, the area of ​​the electrode A is 0.7 to 1.3 times the area of ​​the electrode B.

[0019] Preferably, the sum of the number of the electrodes A and the number of the electrodes B is 7-12.

[0020] Preferably, a plurality of strip-shaped protrusions are provided on the substrate, and several of the protrusions are arranged vertically and parallel to each other, with a gap between two adjacent protrusions, and one of the electrode A and the electrode B is arranged on the protrusion, and the other is arranged on the substrate.

[0021] In the present invention, the staggered design of electrode A and electrode B can improve the distribution uniformity of the electrolyte on the electrode surface, reduce local concentration polarization, and thus improve the ion transmission efficiency.

[0022] In the present invention, the highly staggered electrode layout can prevent direct contact between electrode A and electrode B, thereby reducing the risk of short circuit.

[0023] Preferably, the width of the protrusion is L1, the width of the gap between any two adjacent protrusions is L2, and L1<L2.

[0024] Preferably, L2=(1.2-1.8)L1.

[0025] Preferably, the protrusion height of the protrusion is H1, H1=(0.3-0.5)L1, and the thickness of the electrode A and the electrode B are both less than 0.2L1.

[0026] Preferably, the sum of the widths of the plurality of protrusions is 40% to 80% of the sum of the plurality of gaps.

[0027] Preferably, both the electrode A and the electrode B are powered by a constant voltage.

[0028] Compared with the prior art, the advantages of the present invention include:

[0029] (1) The large modular hydrogen production electrolyzer provided by the present invention can reduce the occurrence of electrode polarization by alternating high-frequency power supply between electrode A and electrode B, thereby improving the electrolysis efficiency of the electrolyte;

[0030] (2) The present invention provides a large modular hydrogen production electrolyzer, in which the electrode assembly uses pulse current to help bubbles detach from the electrode surface faster, reduce the coverage of bubbles on electrodes A and B, and increase the effective reaction area;

[0031] (3) In a large modular hydrogen production electrolyzer provided by the present invention, the on-off mode of the electrode assembly can prevent bubbles from accumulating on the surfaces of electrode A and electrode B, thereby reducing the resistance of the electrode assembly;

[0032] (4) The present invention provides a large modular hydrogen production electrolyzer, in which the electrodes A and B are energized alternately, so that the electrodes A and B have more opportunities to be cooled by water, thereby reducing Joule heat, lowering the electrolyzer temperature, and reducing cooling requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 The internal structure of a module unit of a large modular hydrogen production electrolyzer in the present invention is schematic;

[0035] Figure 2 It is a schematic diagram of the structure of the electrode assembly in the present invention.

[0036] Reference numerals:

[0037] 1. Substrate; 2. Diaphragm; 3. Electrode A; 4. Electrode B; 5. Raised portion. DETAILED DESCRIPTION

[0038] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The following will further explain the technical solution, its implementation process and principle, etc. in conjunction with the drawings in the embodiments of this application and specific implementation cases.

[0039] It should be noted that the embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, the present invention covers any substitution, modification, equivalent method and scheme made on the spirit, principle and scope of the present invention defined by the claims. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the description of the present application, "first", "second", "third" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "an" and other similar words do not indicate a quantity limitation, but indicate the existence of at least one. "Include" or "comprise" and other similar words mean that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalents, and do not exclude other elements or objects. "Connect" or "connected" and other similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0041] In the description of the present application, the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, when positional terms such as both sides, outside, up and down are used, it should be understood that they are only used to facilitate understanding and description, considering that the structure may be facing other positions.

[0042] In the description of this application, unless otherwise clearly specified and limited, the technical or scientific terms used should have the usual meanings understood by persons with general skills in the field to which this application belongs. Terms such as "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection, or an integrated connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] The embodiments of the present invention are intended to introduce and illustrate the structural composition of a large-scale modular hydrogen production electrolyzer and the coordination relationship between the various components. Unless otherwise specified, the dimensions, materials, and manufacturing processes of the various components suitable for the large-scale modular hydrogen production electrolyzer in the embodiments of the present invention can be selected according to specific circumstances and are not specifically limited or described herein.

[0044] Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the following detailed description of the present invention. For those skilled in the art, the present invention can be fully understood without the description of these details.

[0045] Example 1

[0046] See also Figure 1 and Figure 2 , a large modular hydrogen production electrolyzer comprising multiple module units.

[0047] A plurality of module units include bipolar plates and diaphragms 2 stacked in sequence. After the plurality of module units are assembled, both sides of the hydrogen production electrolyzer are monopolar plates, and anodes and cathodes are alternately arranged between the plurality of bipolar plates. The anodes and cathodes are separated by diaphragms 2. The space where the anodes are located is an oxygen production chamber, and the space where the cathodes are located is a hydrogen production chamber, thereby forming a plurality of small chambers for modular hydrogen production. The electrolyte inside the hydrogen production chamber and the oxygen production chamber enters from the pipeline at the bottom of the electrolyzer, and is discharged through the pipeline at the top of the electrolyzer after electrolysis. A gas-liquid separator is provided at the top of the hydrogen production electrolyzer, and a hydrogen exhaust pipe and an oxygen exhaust pipe are provided in the gas-liquid separator. The gas-liquid separator is connected to the hydrogen production chamber and the oxygen production chamber through a plurality of feeding pipes. Each hydrogen production chamber and the oxygen production chamber is connected to the gas-liquid separator through a separate feeding pipe. Both the monopolar plate and the bipolar plate are electrode assemblies.

[0048] Specifically, the circulation process of the electrolyte is to start from the alkali liquid circulation tank, be transported to the cathode and anode feed main pipes of the electrolytic cell by a liquid pump, and then flow into each small chamber of the electrolytic cell through the respective connected pipes;

[0049] The electrolyte, hydrogen and oxygen mixture after electrolysis enter the gas-liquid separator from multiple feeding pipes on the top of the electrolytic cell. Here, hydrogen and oxygen are separated and discharged through the hydrogen exhaust pipe and oxygen exhaust pipe respectively, and the electrolyte that has not been completely reacted returns to the alkali liquid circulation tank; the electrolyte that has not been completely reacted returns to the alkali liquid circulation tank through the circulation system, and when the liquid level drops, water is automatically or manually added to the electrolysis chamber through the water supply pipe to maintain the concentration and level of the electrolyte.

[0050] The separated hydrogen and oxygen enter the drying and purification device, the specific structure of which is the same as that of the prior art and will not be described in detail here, to remove moisture and other impurities to improve the purity of the gas. The treated hydrogen and oxygen are transported to the user end.

[0051] The entire hydrogen production process is monitored by a control system, including sensors, control units and actuators. The sensors monitor key parameters such as temperature, pressure, liquid level, current and voltage in real time and transmit the information to the control unit for precise control.

[0052] In this embodiment, the difference between the monopolar plate and the bipolar plate is that the monopolar plate has an electrode on only one side, while the bipolar plate has electrodes on both sides, and a single bipolar plate can only be used as either an anode or a cathode.

[0053] See also Figure 1 and Figure 2 , a large modular hydrogen production electrolyzer, including an electrode assembly, wherein the monopolar plate and the bipolar plate are both electrode assemblies.

[0054] The electrode assembly includes a substrate 1, on which a plurality of protrusions 5 are arranged. The protrusions 5 are strip-shaped and vertically arranged on the substrate 1. The plurality of protrusions 5 are parallel to each other, and a gap is left between two adjacent protrusions 5. A plurality of electrodes A3 and a plurality of electrodes B4 are arranged on the substrate 1. In this embodiment, the electrode A3 is fixedly mounted on the protrusion 5, and the electrode B4 is arranged in the gap. In other embodiments, the electrode B4 is fixedly mounted on the protrusion 5, and the electrode A3 is arranged in the gap.

[0055] In this embodiment, the electrode A3 and the electrode B4 are both strip-shaped and parallel to each other, and the electrode A3 and the electrode B4 are both vertically arranged, so that the electrode A3 and the electrode B4 can adapt to the shape of the substrate 1 and fit together.

[0056] Specifically, the width of the protrusion 5 is L1, and the width of the gap left between any two adjacent protrusions 5 is L2, L1<L2, and the widths of the electrode A3 and the electrode B4 are respectively the same as the protrusion 5 and the gap where they are located. Electrodes of different widths can optimize the contact area between the electrolyte and the electrode, improve the ion transmission path, and thus improve the mass transfer efficiency, L2=(1.2~1.8)L1, in this embodiment, L2=1.2L1, in other embodiments, L2=1.3L1, L2=1.4L1, L2=1.5L1, L2=1.6L1, L2=1.7L1, L2=1.8L1, any one of them.

[0057] In this embodiment, the design of different widths of electrode A3 and several electrodes B4 can reduce the current density non-uniformity on the electrode surface, reduce concentration polarization, and thus improve the efficiency of the electrochemical reaction.

[0058] In this embodiment, in energy storage devices such as lithium-ion batteries, electrode designs of different widths can achieve a gradient structure, optimize lithium ion transmission and electron conduction paths inside the electrode, thereby improving the energy density and power density of the battery, and can better adapt to high-rate charging and discharging requirements and reduce electrode polarization under high currents.

[0059] Specifically, the area of ​​electrode A3 is 0.7 to 1.3 times the area of ​​electrode B4. In the present embodiment, the area of ​​electrode A3 is 0.7 times the area of ​​electrode B4. In other embodiments, the area of ​​electrode A3 may be any one of 0.8, 0.9, 1.0, 1.2, and 1.3 times the area of ​​electrode B4.

[0060] In this embodiment, the difference in electrode area can adjust the distribution of current density. Electrode A3 with a smaller area will have a higher current density at the same current, which may accelerate the electrochemical reaction rate.

[0061] In this embodiment, by adjusting the area ratio of electrode A3 and electrode B4, the reaction conditions on the electrode surface can be optimized and concentration polarization and electrochemical polarization can be reduced. Electrodes with smaller areas may produce higher local current density during the reaction, thereby accelerating the diffusion of reactants and reducing polarization.

[0062] Preferably, the sum of the widths of the plurality of protrusions 5 is 40% to 80% of the sum of the plurality of gaps. In this embodiment, the number of protrusions 5 is 5, the number of gaps is 4, and the sum of the widths of the protrusions 5 is 40% of the sum of the gaps. In other embodiments, the sum of the widths of the plurality of protrusions 5 may be 50%, 60%, 70%, or 80% of the sum of the plurality of gaps.

[0063] In this embodiment, the sum of the widths of the protrusions 5 is 40% of the sum of the gaps, thereby limiting the overall size ratio of the electrodes A3 and the electrodes B4, optimizing the current distribution between the electrodes and reducing the non-uniformity of the current density.

[0064] Specifically, the sum of the number of electrodes A3 and the number of electrodes B4 is 7 to 12. In this embodiment, the number of electrodes A3 is 5, and the number of electrodes B4 is 4. In other embodiments, the sum of the number of electrodes A3 and the number of electrodes B4 can be any one of 7, 8, 10, 11, and 12. By reasonably allocating the number of electrodes, the distribution of current between the electrodes can be optimized and the problem of local overload or uneven current density can be reduced.

[0065] In this embodiment, electrode A3 and electrode B4 are powered independently of each other, so that high-frequency alternating power can be supplied between electrode A3 and electrode B4, and the alternating frequency is 30Hz to 120Hz. In this embodiment, the alternating frequency of electrode A3 and electrode B4 is 30Hz. In other embodiments, the alternating frequency of electrode A3 and electrode B4 can be any one of 40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, and 120Hz.

[0066] In this embodiment, high-frequency alternating current can quickly switch the polarity or current state of the electrode within a millisecond time scale, thereby achieving a more efficient electrochemical reaction. This mode can significantly improve the conversion rate of reactants and the selectivity of products. Especially in organic synthesis, high-frequency alternating current can achieve a unique reaction path and higher chemical selectivity.

[0067] In this embodiment, high-frequency alternating energization can effectively reduce the polarization phenomenon on the electrode surface. By quickly switching the energized state of the electrode, the electrode surface can be prevented from being in a high potential state for a long time, thereby reducing concentration polarization and electrochemical polarization.

[0068] Specifically, the protrusion height of the protrusion 5 is H1, H1=(0.3~0.5)L1, the thickness of the electrode A3 and the electrode B4 are both less than 0.2L1, in this embodiment, H1=0.3L1, in other embodiments, H1=0.4L1, H1=0.5L1.

[0069] In this embodiment, a smaller electrode thickness of less than 0.2L1 and a reasonable protrusion height H1 = 0.3-0.5L1 can significantly improve the mass transfer efficiency of the electrolyte on the electrode surface. This design can reduce the ion transmission path, reduce concentration polarization, and thus improve the overall efficiency of the electrochemical reaction.

[0070] Specifically, both electrode A3 and electrode B4 are powered by a constant voltage, which can accurately control the electrode potential, thereby directly manipulating the thermodynamics and kinetics of the electrochemical reaction. This power supply method can ensure that the potential on the electrode surface remains stable, so that the electrochemical reaction proceeds under preset conditions, avoiding reaction instability caused by voltage fluctuations.

[0071] In this embodiment, the large modular hydrogen production electrolyzer delivers the electrolyte into the hydrogen production chamber and the oxygen production chamber through the pipeline at the bottom thereof, and the hydrogen production and oxygen production operations are performed respectively through the operation of the electrode assembly, and the hydrogen produced by the multiple hydrogen production chambers is discharged through the same hydrogen exhaust pipe, and the oxygen produced by the multiple oxygen production chambers is discharged through the same oxygen exhaust pipe. After the electrolysis is completed, the electrolyte will be discharged through the pipelines at the top of the hydrogen production chamber and the oxygen production chamber. The working principle of the electrode assembly is as follows:

[0072] When the electrode assembly is working, the electrode A3 and the electrode B4 are energized alternately periodically, and one of the electrode A3 and the electrode B4 is always in the energized state, so that the hydrogen or oxygen production operation is performed by periodically and continuously energizing.

[0073] Specifically, the power supply of electrode A3 and electrode B4 adopts a pulse power supply mode, and the power-on time of electrode A3 and electrode B4 is controlled by adjusting the pulse width and cycle. There are many devices for implementing pulse power supply, and the following examples are given:

[0074] First, the time relay periodically switches the power-on state of electrode A3 and electrode B4 according to the preset time interval. The relay is set to switch once every 1 second. Electrode A3 is powered on for 1 second and then de-energized. At the same time, electrode B4 starts to be powered on for 2 seconds, and then this process is repeated;

[0075] Secondly, the power module provides a stable DC power supply to the electrode assembly. During the alternating power-on process, the power module supplies power to electrode A3 and electrode B4 respectively through the relay control circuit;

[0076] Finally, the control circuit ensures that the current and voltage of the electrode are stable when powered on. Through components such as operational amplifiers, the current density of the electrode can be accurately controlled to avoid overloading or underloading;

[0077] In summary, the power module provides stable DC input, the time relay switches the power-on state of electrode A3 and electrode B4 at preset time intervals, and the control circuit adjusts the current and voltage of the electrodes to ensure stable conditions for the electrochemical reaction. During the alternating power-on process, electrode A3 and electrode B4 respectively undergo electrochemical reactions to achieve periodic alternating power supply.

[0078] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, some simple deductions or substitutions can be made without departing from the concept of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A large modular hydrogen production electrolyzer, comprising an electrode assembly, characterized in that: The electrode assembly comprises a substrate (1), on which an electrode A (3) and an electrode B (4) are arranged, wherein the electrode A (3) and the electrode B (4) are powered independently of each other, and the electrode A (3) and the electrode B (4) are powered alternately, and the alternating frequency is 30 Hz to 120 Hz; when the electrode assembly is working, one of the electrode A (3) and the electrode B (4) is always in a powered state.

2. A large modular hydrogen production electrolyzer according to claim 1, characterized in that: The electrode A (3) and the electrode B (4) are both strip-shaped and parallel to each other, and the electrode A (3) and the electrode B (4) are both vertically arranged.

3. A large modular hydrogen production electrolyzer according to claim 2, characterized in that: The area of ​​the electrode A (3) is 0.7 to 1.3 times the area of ​​the electrode B (4).

4. A large modular hydrogen production electrolyzer according to claim 2, characterized in that: The total number of the electrodes A (3) and the electrodes B (4) is 7 to 12.

5. A large modular hydrogen production electrolyzer according to claim 1, characterized in that: The substrate (1) is provided with a plurality of strip-shaped protrusions (5), wherein the protrusions (5) are arranged vertically and parallel to each other, and a gap is left between two adjacent protrusions (5); one of the electrode A (3) and the electrode B (4) is arranged on the protrusion (5), and the other is arranged on the substrate (1).

6. A large modular hydrogen production electrolyzer according to claim 5, characterized in that: The width of the protrusion (5) is L1, and the width of the gap between any two adjacent protrusions (5) is L2, where L1<L2.

7. A large modular hydrogen production electrolyzer according to claim 6, characterized in that: The L2=(1.2~1.8)L1.

8. A large modular hydrogen production electrolyzer according to claim 6, characterized in that: The protrusion height of the protrusion (5) is H1, H1=(0.3-0.5)L1, and the thickness of the electrode A (3) and the electrode B (4) are both less than 0.2L1.

9. A large modular hydrogen production electrolyzer according to claim 6, characterized in that: The sum of the widths of the plurality of protrusions (5) is 40% to 80% of the sum of the plurality of gaps.

10. A large modular hydrogen production electrolyzer according to claim 1, characterized in that: The electrode A (3) and the electrode B (4) are both powered by a constant voltage.

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