Electrode power supply control method and system for electrolysis process and storage medium

Abstract

The invention belongs to the technical field of electrolysis processes, and particularly relates to an electrode power supply control method and system for an electrolysis process and a storage medium. The method comprises the following steps: loading a first pulse voltage between an anode and a cathode to rapidly increase the voltage between the two electrodes; detecting a voltage rising waveform and / or current in real time; when the condition 1 and / or the condition 2 are / is met, stopping loading the first pulse voltage, and applying a second pulse voltage between the first electrode and the second electrode; the polarity directions of the second pulse voltage and the first pulse voltage are opposite; the condition 1 is that the slope of the voltage rising waveform is reduced, and then the slope is recovered; the condition 2 is that the stable current value is increased, and then the current is recovered to the state before the current is increased; in the electrolysis process, the steps are repeated. The efficiency of the electrolysis process can be improved, the stability and the service life of the electrode catalyst are guaranteed, and therefore the electrode catalyst has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolytic process, and in particular relates to an electrode power supply control method, system and storage medium for electrolytic process. Background Art

[0002] The electrolysis process is a process that uses electric current to pass through electrolyte solutions or molten substances to cause oxidation and reduction reactions between the anode and cathode to achieve separation, purification or preparation of substances. It is widely used in metal refining, electroplating, electrolysis of water to produce hydrogen, chlor-alkali industry and other fields.

[0003] The core of water electrolysis hydrogen / oxygen technology is to improve the efficiency of electricity conversion and reduce production costs. The development direction of catalytic electrodes is mainly focused on improving catalytic efficiency, reducing costs and enhancing stability. At present, the catalytic electrodes of water electrolysis hydrogen / oxygen technology mainly use porous nickel electrodes and high-performance nickel-based alloy electrodes. In order to improve the catalytic efficiency, researchers are developing more efficient water electrolysis catalysts, especially bifunctional catalysts, which can catalyze hydrogen and oxygen evolution reactions at the same time, thereby simplifying the electrolysis system and reducing costs. For example, a research team from Yunnan University has developed a catalyst of Ir single atoms coupled to NiFe LDH / NiMo heterogeneous interface, which exhibits efficient catalytic activity in alkaline electrolytes and remains stable during long-term operation.

[0004] These existing catalytic electrodes still have some problems, such as high cost, poor stability, and performance degradation at high current density. The catalyst is easy to fall off or deactivate at high current density, resulting in a decrease in catalytic performance. The specific reasons for catalyst deactivation include particle agglomeration, phase change, site poisoning, site dissolution, catalyst layer / particle shedding, and bubble blockage. These factors will lead to a reduction or passivation of active sites, thereby reducing the electrolysis efficiency.

[0005] At present, the research on solutions to reduce the activity of catalytic electrodes is mainly focused on improving the catalyst itself. For example, the team of Academician Sun Licheng developed a catalyst that can stably operate for more than 19,100 hours at a high current density through a new process; the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences and the RIKEN Institute of Physical and Chemical Research in Japan have cooperated to prepare a manganese dioxide electrolysis catalyst with ultra-long stability. However, these studies are still some distance away from commercial application.

[0006] On the other hand, improving the electrolysis process, such as controlling the power applied to the electrode, is also a feasible solution to improve the stability of the catalytic electrode. However, there are few studies in this area, and no research has been seen on power control for the electrolysis process to improve electrode stability and extend electrode life. Summary of the invention

[0007] In view of the problems in the prior art, the present invention provides an electrode power supply control method, system and storage medium for an electrolysis process.

[0008] A method for controlling an electrode power supply for an electrolytic process, comprising: Applying a first pulse voltage between the anode and the cathode to rapidly increase the voltage between the two electrodes; Real-time detection of voltage rise waveform and / or current; When condition 1 and / or condition 2 is met, the first pulse voltage is stopped, and a second pulse voltage is applied between the first electrode and the second electrode; the second pulse voltage has a polarity opposite to that of the first pulse voltage; The condition 1 is: the slope of the voltage rising waveform decreases, and then the slope recovers; The condition 2 is: the stable current value increases, and then the current returns to the state before the increase; During the electrolysis process, the above steps are repeated.

[0009] Preferably, the first pulse voltage increases in voltage value at a rate greater than or equal to 3V / μs.

[0010] Preferably, the value of the second pulse voltage does not exceed the electrode potential of the electrochemical reaction in the electrolysis process.

[0011] Preferably, the electrolysis process is a water electrolysis process, and the value of the second pulse voltage does not exceed 1.27V.

[0012] Preferably, the duration of the second pulse voltage is less than or equal to 100 μs.

[0013] Preferably, the reference 0 V of the first pulse voltage is set on the cathode.

[0014] Preferably, the reference 0 V of the second pulse voltage is set on the cathode.

[0015] The present invention also provides a system for implementing the above-mentioned electrode power supply control method for electrolysis process, comprising: A pulse signal power supply for applying voltage to the anode and cathode; A power supply control module is used to control the output of the pulse signal power supply according to the above-mentioned electrode power supply control method for electrolysis process.

[0016] The present invention also provides an electrolytic cell device, wherein the electrolytic cell device is integrated with the above system.

[0017] The present invention also provides a computer-readable storage medium, on which is stored: a computer program for implementing the above-mentioned electrode power supply control method.

[0018] The present invention proposes for the first time a method for controlling electrode power supply by using pulse voltage waveform or current change in an electrolysis process. By using the method of the present invention, the coating on the electrode surface (such as the oxidation product on the anode surface in the water electrolysis process) can be removed in real time at a precise time point during the electrolysis process, thereby always ensuring the reaction activity of the catalyst on the electrode surface. The present invention is conducive to the efficient electrolysis process, reduces the energy consumption of electrolysis, and can improve the stability and service life of the electrode catalyst. Therefore, the present invention has a good application prospect.

[0019] Obviously, according to the above contents of the present invention, in accordance with common technical knowledge and customary means in the art, without departing from the above basic technical ideas of the present invention, other various forms of modification, replacement or change may be made.

[0020] The above contents of the present invention are further described in detail below through specific implementation methods in the form of embodiments. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above contents of the present invention belong to the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The hydroxyl group (OH - ) Schematic diagram of migration toward the anode; Figure 2 Schematic diagram of the conversion process of hydroxyl groups on the anode surface; Figure 3 A schematic diagram of the potential change caused by the release of electrons by hydroxyl groups on the anode surface; Figure 4 Schematic diagram of the step in the pulse voltage waveform caused by the release of electrons by hydroxyl groups on the anode surface; Figure 5 It is a schematic diagram of the structure of the experimental device of the power supply control method of the present invention in Experimental Example 1; Figure 6 It is the MCU control flow chart of the experimental device of the power control method of the present invention in Experimental Example 1; Figure 7 It is a schematic diagram of the structure of the control experimental device of the existing method in Experimental Example 1; Figure 8 This is a test result diagram of average current and average voltage of the power supply control method of the present invention and the prior art method in Experimental Example 1. DETAILED DESCRIPTION

[0022] It should be noted that the algorithms of data collection, transmission, storage and processing steps not specifically described in the embodiments, as well as the hardware structure, circuit connection, etc. not specifically described can all be implemented through the contents disclosed in the prior art.

[0023] Example 1 Electrode power supply control method, system and storage medium for electrolysis process The system of this embodiment includes: A pulse signal power supply for applying voltage to the anode and cathode; The power supply control module is used to control the output of the pulse signal power supply in the electrolysis process.

[0024] The control method of the pulse signal power supply comprises the following steps: Applying a first pulse voltage between the anode and the cathode to rapidly increase the voltage between the two electrodes; Real-time detection of voltage rise waveform and / or current; When condition 1 and / or condition 2 is met, the first pulse voltage is stopped, and a second pulse voltage is applied between the first electrode and the second electrode; the second pulse voltage has a polarity opposite to that of the first pulse voltage; The condition 1 is: the slope of the voltage rising waveform decreases, and then the slope recovers; The condition 2 is: the stable current value increases, and then the current returns to the state before the increase; During the electrolysis process, the above steps are repeated.

[0025] Wherein, as a preferred mode, the first pulse voltage increases the voltage value at a rate greater than or equal to 3V / μs. The numerical value of the second pulse voltage does not exceed the electrode potential of the electrochemical reaction in the electrolysis process. For example, taking the electrolysis process of water as an example, the numerical value of the second pulse voltage does not exceed 1.27 V. The duration of the second pulse voltage is less than or equal to 100μs. The reference 0 V of the first pulse voltage and the second pulse voltage is set on the cathode.

[0026] The following uses the water electrolysis process as an example to illustrate the principle of controlling the output of the pulse signal power supply in this embodiment: The device for electrolyzing water includes two electrodes, one is an anode connected to the positive output of an electrolysis power supply; the other is a cathode connected to the negative output of the electrolysis power supply; the two electrodes are not in contact and are placed in an electrolyte with water as the solute at the same time.

[0027] When a voltage is applied between the two electrodes of the electrolysis device, the hydroxyl radical (OH - ) migrates toward the anode (e.g. Figure 1 as shown).

[0028] The hydroxyl group near the anode surface, because its component oxygen atom has more electrons and hydrogen atom has fewer electrons, under the action of the anode electric field, the hydroxyl oxygen atom moves toward the electrode interface, while the hydrogen atom (at this time a proton) moves away.

[0029] In the process of approaching, when the hydrogen-oxygen electron cloud (formed by the movement of one electron) that holds the hydroxyl group in contact with the anode conductive material, the electron is captured by the anode, and the hydroxyl group loses its hold and disintegrates, releasing oxygen, while the proton moves away from the anode toward the cathode (such as Figure 2 as shown).

[0030] The release of electrons by hydroxyl groups on the anode surface is an instantaneous process, which will affect the voltage of the anode conductor near the contact point, forming an instantaneous low-potential pulse. At this time, electron exchange is taking place. The potential change graph is as follows: Figure 3 shown.

[0031] When the electrode is connected to a pulse signal power supply, under the condition that the electrolyte has good conductivity, it can be observed that there are obvious steps at the pulse front (such as Figure 4 ).

[0032] This step is the voltage drop caused by electron exchange. This phenomenon can be detected when all hydroxyl groups on the anode surface exchange electrons uniformly at the pulse front edge. It is difficult to detect in normal constant voltage or constant current electrolysis because hydroxyl groups in the liquid continuously release electrons.

[0033] When the hydroxyl releases electrons, the oxygen atom approaches the surface of the anode electrode. At the moment of release, it can be considered that an electron cloud is formed between the oxygen atom and the electrode material (considered as a chemical bond), causing the newly formed oxygen element to adhere to and cover the electrode surface. Although the electrode is a conductive material and the shared electrons will disappear inside the electrode, the instantaneous electron sharing has already created a fairly strong adsorption force between the oxygen element and the electrode material.

[0034] The newly generated oxygen covers the electrode surface, which severely inhibits the subsequent contact between the hydroxyl group and the electrode surface and the opportunity to release electrons. In terms of the electrolytic performance of the electrolytic cell, a higher electrode driving voltage is required.

[0035] In addition, under constant voltage or constant current electrolysis, hydroxyl groups release and stop releasing electrons at different points of the electrode, which means that different tiny high-frequency currents (electron flows) will appear at different locations on the anode surface, and the electromagnetic induction will form eddy currents in the anode conductor, resulting in additional power consumption and heat generation. Therefore, it can be observed that the anode heats up severely during water electrolysis.

[0036] In the prior art, the solution to the above problem is usually to use molecular or structural modified materials (catalytic materials) to make electrodes. First, modify the material molecules so that their surface forms multiple electric field singular points (electric field distortion) at nanometers or equivalent sizes, causing local discharge and the separation of newly generated oxygen; second, modify the material to change the surface microstructure of the material, increase the surface area of ​​the material, and increase the electron exchange area.

[0037] However, the electrolysis system is a strong redox system. In particular, even if the electrolyte is alkaline, the anode region is still in a strong acid state, so the choice of electrode materials is very limited. Those that meet the requirements of molecular or structural modification, especially porous or rough surfaces, are difficult to withstand tens of thousands or hundreds of thousands of hours of continuous operation.

[0038] In summary, in order to meet the actual requirements of oxygen and hydrogen production by water electrolysis, the service life can only be given priority. To improve its Faraday efficiency, the working principle of simulated catalytic materials, namely electrically driven anode catalysis, is adopted.

[0039] After adopting the power control method of this embodiment, the principle of the change of the electrode surface is as follows: After the first pulse voltage is applied, the voltage rises at a very fast rate. When the voltage rise waveform slows down (the slope decreases) and the current increases, electrons are exchanged on the anode surface. The current returns to the state before the increase, and the voltage rises at a similar rate to before (the slope is restored). At this time, the electrons have been transferred from the hydroxyl group to the electrode conductor, and the hydroxyl group disintegrates to produce new oxygen molecules. However, the new oxygen molecules are attached to the electrode surface and have negative electrical properties. Then, the second pulse voltage with reversed polarity is applied, and the anode of the electrolytic cell is connected to the negative pole of the power supply. The negatively charged oxygen molecules repel each other from the electrode and leave the electrode surface. At this point, the conditions are ready for the next round of applying the first pulse voltage.

[0040] The value of the second pulse voltage does not exceed the electrode potential of the electrolysis system. In the water electrolysis system, it does not exceed 1.27V. The purpose of this setting is to ensure that the flipped second pulse voltage does not cause gas precipitation at the anode electrode and the cathode electrode to ensure the purity of the gas produced by the electrolytic cell. The time does not exceed 100μs. The purpose of this setting is to allow only oxygen molecules to separate from the electrode surface. The shorter the time, the higher the time utilization rate.

[0041] It should be noted that this embodiment uses the water electrolysis process as an example to illustrate the principle, but the technical solution of this embodiment is not only applicable to the water electrolysis process. Any other process in which electrode adsorption occurs during the electrolysis process, resulting in reduced activity, can use the method of this embodiment to control the electrode power supply.

[0042] Example 2 Electrolyzer Equipment The present invention also provides an electrolytic cell device, the electrolytic cell device comprising an electrolytic cell body, a cathode and an anode, wherein voltage is applied to the cathode and the anode by a pulse signal power supply. The electrolytic cell device is integrated with the system described in Example 1.

[0043] The technical effects of the present invention are further illustrated by experiments below.

[0044] Experimental Example 1 Comparison between the power supply control method of the present invention and the existing method 1. Experimental Methods 1. Experimental device of the power supply control method of the present invention Establishing the experimental system Figure 5 As shown, specifically: Take a bidirectional DC power supply, adjust the power supply to DC+6V (based on the neutral end 0V) at the positive output end and DC-1.0V (based on the neutral end 0V) at the negative output end. Connect the cathode in the electrolytic cell to the 0V (reference potential) end of the power supply, and connect the anode of the electrolytic cell to the output end of the catalytic power supply (pulse power supply).

[0045] The anode and cathode of the electrolytic cell are made of the same conductive material. This experiment uses metal oxide sintered material (metal oxide ceramic), the main requirement of which is to prevent electrical corrosion during the experiment.

[0046] The anode of the electrolytic cell is connected to the output end of the catalytic power supply (pulse power supply). The catalytic power supply is a reverse pulse power signal source composed of a push-wrist circuit composed of two Darlington tubes, and the Darlington tube is controlled by a B3 transistor (S9018) switch.

[0047] One of the characteristics of water electrolysis is that the voltage is not high, but the current is huge. Its power supply usually adopts low voltage and high current type, and thyristor is often used as rectification control element in industry. Although thyristor is a good switching device, its characteristic cannot be actively turned off, and it is difficult to complete the required pulse flipping process. Usually, the electronic switching device that is easy to control on and off is transistor, but the amplification factor (hFE) of high-power (high-current) transistor catalytic power supply is low, and the output signal of the microcontroller is difficult to drive. Therefore, in order to realize the drive of small signals, two transistors are combined into a Darlington tube, so as to achieve reliable drive control.

[0048] The main power devices of Darlington tubes B1 and B2 in the catalytic power supply are D44VH10G and D45VH10G pairs of tubes. These two transistors can reach a dissipation power of 83W and a current of 15A, but their hFE=20, the amplification factor is too small, resulting in insufficient circuit fan-out. Therefore, a small power tube is connected to its base to form a Darlington tube circuit structure, so that the comprehensive amplification factor reaches 3000 to adapt to the control output capability of the MCU.

[0049] The MCU uses Microchip's PIC16F877A, which has A / D conversion, storage and other functions. The experiment uses a 4MHz crystal oscillator, which provides a 1μs control and sampling interval and a maximum output of 20mA. The output of the MCU is then isolated by the D1 Schmitt reverse trigger CD40106 to obtain a steeper leading and trailing edge control signal.

[0050] The anode of the electrolytic cell is also connected to a current sensor and a voltage sensor. The current sensor is a high-speed current signal acquisition sensor with a Risym AH3503 linear Hall element as the working device, and its induction cutoff frequency can reach 400kHz. It meets the requirements of detecting the electrolysis process. The voltage sensor detects the voltage value and its change between the 0V reference (anode and cathode) loaded on the anode.

[0051] MCU is the control core of the catalytic power supply. At the beginning of the electrolysis process, the MCU outputs a high level, and after the Schmitt trigger (D1) is reversed, a low level is sent to the B3 transistor, and the collector and emitter of B3 are disconnected. At this time, the +6V of the power supply is loaded to the base of B1 and B2 through the resistor R1, causing the collector and emitter of B1 to be turned on and the collector and emitter of B2 to be disconnected. Finally, the display circuit outputs a high level, that is, the voltage between the anodes of the electrolytic cell rises (that is, the first pulse voltage is loaded). During the process, the current sensor and the voltage sensor continuously monitor their changes and send the signal to the MCU. The MCU converts and calculates through A / D. When the voltage waveform is detected to have a step and the current suddenly increases and recovers, it outputs a low level. After the Schmitt trigger (D1) is reversed, a high level is sent to the B3 transistor. The collector and emitter of B3 are connected. At this time, the -1V of the power supply is directly loaded to the base of B1 and B2, causing the collector and emitter of B1 to be disconnected and the collector and emitter of B2 to be turned on. Finally, the circuit outputs a negative level (that is, the second pulse voltage is loaded). The current sensor and voltage sensor then send the subsequent signals to the MCU. When the voltage waveform and current waveform are detected to be restored, the reverse voltage loading is stopped and the MCU high level output is restarted (i.e. the first pulse voltage is loaded). The MCU control flow chart is as follows: Figure 6 shown.

[0052] The configuration of other methods or devices not specifically described shall be performed with reference to the description of Example 1.

[0053] 2. Control experiment device of existing methods Average current-voltage ratio test: Since the catalytic power supply outputs a power pulse signal, in this experimental example, the efficiency under constant current working state is compared by comparing the experimental device. Therefore, it is necessary to measure the average current and voltage acting on the electrolytic cell electrodes. Figure 7 The measurement circuit is shown.

[0054] The measurement circuit is divided into average current measurement and average voltage measurement.

[0055] Average current measurement: R4 (100mΩ) resistor is connected in series between the catalytic power supply and the anode. When the electrolytic current passes through, a voltage drop is generated. This voltage drop is divided by R3 and R5 (500Ω), and C1 (470μF) capacitor is used at both ends of R3 to form a filtered voltage regulator. The voltage regulator value is proportional to the current flowing through R4. At this time, the average current is: in, It is the voltage stabilizer formed by the C1 capacitor rectification and filtering. is the resistance value of resistor R4.

[0056] Average voltage measurement: R6 and R7 divide the voltage, and the voltage drop generated on R7 is filtered by C2 to form a regulated voltage. The regulated voltage value is proportional to the voltage value on the anode. At this time, the average voltage is: in, It is the voltage stabilizer formed by the C2 capacitor rectification and filtering. is the resistance value of resistor R6, is the resistance value of resistor R7.

[0057] The reason why filter capacitors C1 and C2 are connected in the voltage divider circuit is to avoid affecting the change of the voltage waveform on the anode.

[0058] 2. Experimental Results In the above-mentioned experimental device corresponding to the power supply control method of the present invention, the anode and cathode of the electrolyzer are driven by a pulsating voltage, not a conventional DC constant voltage drive. The purpose of the present invention is to improve the efficiency of the electrolyzer, that is, under the same current size, the lower the electrolysis voltage, the better. In other words, it is hoped that the lower the power, the better. In order to evaluate the electrolysis efficiency, this experiment introduces the concept of "average current-voltage ratio". Its meaning is the ratio of the electrolysis current of the electrolyzer to the average voltage between the positive and negative electrodes. The higher this value, the higher the electrolyzer efficiency. This is because, under the same voltage, the larger the current, the more electron exchanges on the electrodes, the more hydrogen and oxygen are produced, and the smaller the loss.

[0059] The experimental results of the above two experimental devices are as follows Figure 8 And the following table shows: From the above experimental results, it can be seen that when adopting the electrode power supply control method of the present invention, under the same electrolysis current, the electrode voltage decreases, which shows that the average current-voltage ratio of the inventive method is higher. Therefore, the method of the present invention has higher electrolysis efficiency than the electrolysis voltage control method of the prior art, and can reduce the energy consumption of electrolysis.

[0060] It can be seen from the above embodiments that the present invention provides a method for controlling electrode power supply by using pulse voltage waveform or current change in an electrolysis process, which can improve the efficiency of the electrolysis process, reduce electrolysis energy consumption, and ensure the stability and service life of the electrode catalyst. Therefore, the present invention has a good application prospect.

Claims

1. A method for controlling an electrode power supply for an electrolytic process, characterized in that: include: Applying a first pulse voltage between the anode and the cathode to rapidly increase the voltage between the two electrodes; Real-time detection of voltage rise waveform and / or current; When condition 1 and / or condition 2 is met, the first pulse voltage is stopped and a second pulse voltage is applied between the first electrode and the second electrode; The second pulse voltage has a polarity opposite to that of the first pulse voltage; The condition 1 is: the slope of the voltage rising waveform decreases, and then the slope recovers; The condition 2 is: the stable current value increases, and then the current returns to the state before the increase; During the electrolysis process, the above steps are repeated.

2. The electrode power supply control method for electrolysis process according to claim 1, characterized in that: The first pulse voltage increases in voltage value at a rate greater than or equal to 3 V / μs.

3. The electrode power supply control method for electrolysis process according to claim 1, characterized in that: The value of the second pulse voltage does not exceed the electrode potential of the electrochemical reaction in the electrolysis process.

4. The electrode power supply control method for electrolysis process according to claim 3, characterized in that: The electrolysis process is a water electrolysis process, and the value of the second pulse voltage does not exceed 1.27 V.

5. The electrode power supply control method for electrolysis process according to claim 1, characterized in that: The duration of the second pulse voltage is less than or equal to 100 μs.

6. The electrode power supply control method for electrolysis process according to claim 1, characterized in that: A reference 0 V of the first pulse voltage is set on the cathode.

7. The electrode power supply control method for electrolysis process according to claim 1, characterized in that: A reference 0 V of the second pulse voltage is set on the cathode.

8. A system for implementing the electrode power supply control method for electrolysis process according to any one of claims 1 to 7, characterized in that: include: A pulse signal power supply for applying voltage to the anode and cathode; A power supply control module is used to control the output of the pulse signal power supply according to the electrode power supply control method for electrolysis process according to any one of claims 1-7.

9. An electrolytic cell device, characterized in that: The electrolyzer device is integrated with the system of claim 8.

10. A computer-readable storage medium, characterized in that: Stored thereon is: a computer program for implementing the electrode power supply control method for electrolysis process as described in any one of claims 1-7.

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