Flow battery optimizing device

Abstract

The invention provides a flow battery optimizing device which comprises a flow battery electric pile and an embedded ultrasonic sound production device, the flow battery electric pile is charged and discharged by adopting a multi-pulse power supply, the charge and discharge efficiency of a flow battery system is controlled and improved, and a conductive column is arranged between a bipolar plate and an electrode plate in the flow battery electric pile; the ultrasonic sound production device comprises an ultrasonic driving power supply and piezoelectric elements; the piezoelectric elements and the conductive columns are uniformly arranged at intervals in a space between the electrode plate and the bipolar plate; the ultrasonic driving power supply supplies power to the piezoelectric elements to enable the piezoelectric elements to perform ultrasonic vibration, the piezoelectric elements form an integrated structure in the flow battery units based on the ultrasonic vibration to generate an ultrasonic field, and the ultrasonic field acts on the flow battery units; an ultrasonic field is mutually coupled with an electric field under the combined action of the bipolar plate and the electrode plate, so that the charging and discharging processes of the flow battery are optimized, and meanwhile, the morphology of a possibly existing cathode side metal deposition layer is kept flat and compact.

Description

Technical Field

[0001] The present disclosure relates to the field of liquid flow batteries, and in particular to a liquid flow battery optimization device. Background Art

[0002] As a typical electrochemical energy storage device, the migration of electrochemically active substances in the flow battery, the electron conduction and exchange rate on the electrode directly affect the energy conversion and energy storage efficiency. Under a certain current density, when a current passes through the flow battery, the battery will be polarized, and the output voltage will deviate from the ideal voltage. The voltage loss includes ohmic polarization, kinetic polarization, and concentration polarization. Among them, ohmic polarization comes from the impedance of the membrane material, the impedance of the electrolyte, the impedance of the electrode and the bipolar plate, and the impedance of the current collector. The transient polarization curve can be used to quickly analyze the performance of the flow battery and determine the key factors affecting the performance of the flow battery. At a lower current density, the flow battery is controlled by the kinetic polarization process. The reason is that the charge transfer rate between the electrode material and the electrolyte interface is relatively slow. In order to reduce the kinetic polarization, it is necessary to increase the number of reactive points on the electrode surface. There are two ways to increase the number of reactive points on the electrode: modifying the electrode material and improving the battery structure.

[0003] As the current density increases, the battery gradually changes to ohmic polarization control. The ohmic internal resistance of a flow battery is mainly composed of membrane materials, electrode materials, electrolytes, current collector resistance, and contact resistance between each other. In order to reduce the ohmic internal resistance, you can choose diaphragm materials, electrode materials, current collector materials, electrolyte concentration and composition with better conductivity. You can also reduce the battery ohmic internal resistance by improving the battery structure. As the current density increases further, the battery changes to mass transfer control. The mass transfer of active substances limits the reaction. In order to reduce mass transfer polarization, it is necessary to increase the electrolyte flow rate. At the same time, the flow channel can be designed to enhance the electrolyte mass transfer in the battery chamber.

[0004] The performance of liquid flow batteries is determined by three parts: kinetic polarization, ohmic polarization, and mass transfer polarization. In the design process of liquid flow batteries, it is necessary to consider the influence of the material and structural combination characteristics in the liquid flow battery stack, as well as the influence of the operating conditions of the liquid flow battery circulation system. Continuous monitoring and targeted improvement of each part of the control factors related to the performance of the liquid flow battery system should be done well.

[0005] Liquid flow batteries generally use a DC power supply during the charging and discharging process. For liquid flow batteries with metal deposition on the negative electrode side, metal deposition occurs during the charging process with a DC power supply. The DC current is continuous or persistent and will not be interrupted over time. A thick diffusion layer will be formed at the interface between the cathode and the solution, which will reduce the metal ion concentration on the cathode surface and produce concentration polarization, limiting the deposition rate. Using a larger current density will not only fail to increase the deposition rate, but will increase the amount of hydrogen deposition at the cathode, reduce the current efficiency, and produce defects such as hydrogen embrittlement, pinholes, pitting, scorching and blistering. Therefore, DC current has little effect on increasing cathode current density, inhibiting side reactions, reducing impurity content, and improving current distribution. Summary of the invention

[0006] The present disclosure provides a liquid flow battery optimization device to at least solve the above technical problems existing in the prior art.

[0007] According to a first aspect of the present disclosure, a flow battery optimization device is provided, characterized in that the device comprises:

[0008] A liquid flow battery stack and an embedded ultrasonic sound generating device, wherein the liquid flow battery stack is composed of liquid flow battery cells electrically connected in series;

[0009] The liquid flow battery unit comprises: an integrated assembly of a bipolar plate and an electrode plate, an ion exchange membrane, and an electrode frame, wherein the integrated assembly of the electrode plate comprises a negative electrode plate and / or a positive electrode plate, and conductive columns uniformly arranged between the bipolar plate and the negative electrode plate and the positive electrode plate, and the bipolar plate and the negative electrode plate and the positive electrode plate are electrically connected based on the uniformly distributed conductive columns to realize the electrical series connection of the liquid flow battery unit;

[0010] The ultrasonic sound generating device comprises: an ultrasonic driving power supply and a piezoelectric element;

[0011] The piezoelectric element is arranged between the bipolar plate and the positive plate and / or the negative plate. The ultrasonic driving power supply supplies power to the piezoelectric element to make the piezoelectric element perform ultrasonic vibration. The ultrasonic vibration acts on the bipolar plate, the negative plate and / or the positive plate respectively. The relevant parameters of the ultrasonic vibration include the frequency, amplitude and phase of the vibration.

[0012] In one possible implementation, the piezoelectric element is uniformly filled between the positive electrode plate and / or the negative electrode plate and the bipolar plate;

[0013] A resin material resistant to electrolyte corrosion is filled between the bipolar plate and the electrode plate to prevent the conductive column and the piezoelectric element from contacting the electrolyte, and the resin material is also used to fix the relative position between the piezoelectric element and the conductive column;

[0014] The piezoelectric element is a piezoelectric crystal or a piezoelectric film;

[0015] The piezoelectric crystal or the piezoelectric film is arranged on the periphery of the conductive column.

[0016] In one embodiment, the ultrasonic driving power supply is connected to the positive electrode and the negative electrode of the piezoelectric crystal or the piezoelectric film based on a wire, and the frequency, amplitude and phase of the corresponding ultrasonic vibration generated by the piezoelectric crystal or the piezoelectric film are controlled by setting the alternating voltage output by the ultrasonic driving power supply;

[0017] During the charge and discharge process of the flow battery, the electric field generated by the integrated assembly of the bipolar plate and the electrode plate acts on the positive plate and / or the negative plate together, and the conductive pillars evenly distributed on the positive plate and / or the negative plate make the active substances in the diffusion layer of the contact interface between the corresponding electrode and the electrolyte evenly distributed, and the ultrasonic field generated by the ultrasonic vibration of the evenly distributed piezoelectric crystals or the piezoelectric film further acts on the contact interface between the electrode and the electrolyte, so that the active substances in the diffusion layer are further evenly distributed.

[0018] In one possible implementation, the piezoelectric crystal is provided with a positive electrode and a negative electrode, the positive electrode of at least one of the piezoelectric crystals is connected together, and the negative electrode is connected together, so that the upper and lower surfaces are arranged in a consistent manner to form a shared positive electrode and a shared negative electrode structure, and the shared positive electrode and the shared negative electrode structure in at least one of the flow battery cells are connected in series or in parallel and are connected to the ultrasonic drive power supply through a lead wire;

[0019] The positive electrode and the negative electrode of the piezoelectric film are arranged on both sides of the film, and at least one of the piezoelectric films is stacked so that the positive electrode and the negative electrode are connected in series or in parallel to form a piezoelectric film integrated structure, and the piezoelectric film integrated structure in at least one liquid flow battery unit is connected in series or in parallel, and is connected to the ultrasonic drive power supply through the lead wire;

[0020] The ultrasonic driving power source is connected to the positive electrode and the negative electrode of each liquid flow battery unit which are formed into an integrated structure by the piezoelectric crystal or the piezoelectric film based on a distributed wire link;

[0021] The ultrasonic driving power source controls the magnitude of the alternating voltage transmitted to the integrated structure composed of the piezoelectric crystal or the piezoelectric film in each flow battery unit based on the distributed wire link;

[0022] Based on the frequency, amplitude and phase of the ultrasonic vibration, the ultrasonic field is generated in the liquid flow battery unit by an integrated structure composed of the piezoelectric crystal or the piezoelectric film, and acts on each of the liquid flow battery units.

[0023] In one possible implementation, the piezoelectric crystals are evenly distributed between the positive plate and / or the negative plate and the bipolar plate;

[0024] Or the piezoelectric film is evenly distributed between the positive electrode plate and / or the negative electrode plate and the bipolar plate;

[0025] The conductive posts are symmetrically or asymmetrically distributed with the bipolar plate as the center, and the piezoelectric elements are arranged based on the corresponding arrangement of the conductive posts. When the piezoelectric elements are evenly distributed between the positive plate and the negative plate, they are symmetrically or asymmetrically distributed with the bipolar plate as the center, so as to improve the uniformity and consistency of the interface between the electrode plate and the electrolyte in the liquid flow battery unit;

[0026] The external power supply system applies an electric field to each of the flow battery cells in the flow battery stack through the positive and negative current collectors at both ends of the flow battery stack, and couples with the ultrasonic field generated by the piezoelectric element provided in the flow battery cell, and acts together on the interface between each electrode of the flow battery cell and the electrolyte;

[0027] Or the position of the piezoelectric element is set according to the coupling relationship between the ultrasonic field when the piezoelectric element is working and the electric field generated when the flow battery stack is working.

[0028] In one possible implementation, the material of the piezoelectric film includes at least one of the following: polyvinylidene fluoride, polyvinylidene fluoride copolymer, polymer of 3,4-ethylenedioxythiophene monomer, sodium polystyrene sulfonate, aluminum nitride, carbon-based;

[0029] The material of the piezoelectric crystal includes at least one of the following: lead-zinc-titanium compound, lead zirconate titanate, barium titanate, barium strontium titanate, lead lanthanum zirconate titanate, and lithium sulfate;

[0030] The preparation method of the piezoelectric film includes one of the following: sol-gel method, vacuum evaporation method, sputtering method, chemical vapor deposition method, pulsed laser deposition, electrochemical plating; wherein the sputtering method includes radio frequency magnetron sputtering method and direct current magnetron sputtering method;

[0031] The piezoelectric crystal is manufactured by sintering.

[0032] In one possible implementation, the bipolar plate is configured as a closed two-dimensional space structure;

[0033] The closed two-dimensional spatial structure plane of the bipolar plate is parallel to the plane where the ion exchange membrane is located, and the material of the bipolar plate is selected from metal-based, carbon-based, or a metal-based and carbon-based composite based on the materials of the positive electrode and the negative electrode;

[0034] A wire required for connecting an ultrasonic driving power source is arranged in a hollow structure in the closed two-dimensional space structure of the bipolar plate, and the outside of the two-dimensional space structure is a closed plate for isolating the electrolyte.

[0035] In one possible implementation, the flow battery stack uses a multi-pulse power supply for charging and discharging;

[0036] The multi-pulse power source acts on the positive and negative electrodes of each flow battery unit through the positive and negative current collectors at both ends of the flow battery stack and the internal structure of the flow battery stack, so as to affect the positive and negative electrodes and their electrolyte interfaces;

[0037] The multi-pulse power supply includes: a single-pulse power supply and a double-pulse power supply, which are combined or work separately based on the actual charge and discharge conditions of the flow battery stack, and act on the positive and negative current collectors of the flow battery stack;

[0038] Setting single pulse parameters based on the single pulse power supply, including: pulse frequency, pulse duty cycle and pulse peak power, wherein the pulse frequency is calculated based on the pulse on-off cycle;

[0039] Calculating the pulse peak electric energy based on the pulse duty cycle and the pulse average electric energy, and setting the pulse power supply charging and discharging parameters of the single pulse power supply based on the pulse frequency, the pulse duty cycle and the pulse peak electric energy;

[0040] Based on the dual-pulse power supply, dual-pulse parameters are set, including: forward and reverse pulse frequencies, forward and reverse pulse duty ratios, and forward and reverse pulse peak electrical energies, wherein the forward and reverse pulse frequencies are calculated based on the forward pulse on-off cycle and the reverse pulse on-off cycle;

[0041] Calculate the forward and reverse pulse peak energy based on the percentage of the forward pulse time and the reverse pulse time in the pulse working period, the average energy of the forward pulse time, the average energy of the reverse pulse and the forward and reverse pulse duty cycle;

[0042] Setting the pulse power supply charge and discharge parameters of the dual pulse power supply based on the positive and reverse pulse frequencies, the positive and reverse pulse duty ratios and the positive and reverse pulse peak electrical energies;

[0043] Wherein, the electrical energy input or output includes: pulse current, pulse voltage and pulse power;

[0044] When the multi-pulse power supply is used to charge the liquid flow battery system, different pulse electric energies and combinations thereof are set based on the pulse power supply charging parameters, so that the charging efficiency of the liquid flow battery system is improved;

[0045] Based on the average pulse electric energy, the peak pulse electric energy density and the positive and reverse pulse duty ratios during the discharge process, the discharge efficiency of the liquid flow battery system is controlled and improved.

[0046] In one possible implementation, the multi-pulse power source acts on a flow battery system whose cathode side is a metal deposition type;

[0047] When the flow battery is charged, different pulse electric energies and combinations thereof are set based on the charging parameters of the multi-pulse power supply to control the process of metal electrodeposition on the negative electrode plate, wherein the pulse electric energy includes pulse current, pulse voltage and pulse power;

[0048] When the liquid flow battery is discharged, different pulse electric energies and combinations thereof are set based on the discharge parameters of the multi-pulse power supply to control the electrolysis process of the metal on the negative plate, wherein the pulse electric energy includes pulse current, pulse voltage and pulse power;

[0049] Based on the electrodeposition process of the metal on the negative electrode side during the charging process, a pulse power supply charging parameter is selected, and the flow battery stack is charged based on the pulse power supply charging parameter to obtain a fine, uniform and smooth metal deposition layer;

[0050] Based on the electrolysis process of the metal on the negative electrode side during the discharge process, the average pulse power, the peak pulse power density and the positive and reverse pulse duty ratios during the discharge of the flow battery are adjusted so that the metal deposition layer is ablated layer by layer during the electrolysis process;

[0051] Based on the average pulse electric energy, the peak pulse electric energy density and the positive and reverse pulse duty ratios during the charge and discharge process, the piezoelectric element arranged in the liquid flow battery unit generates the corresponding ultrasonic field, which is coupled with the electric field of the bipolar plate and the electrode plate, so that the morphology of the metal deposition layer on the cathode side remains flat and dense.

[0052] In one possible implementation, the device further comprises a flow battery management system;

[0053] The liquid flow battery management system includes a power supply and a control system of the liquid flow battery and an ultrasonic power supply and a control system. When the liquid flow battery is a metal deposition type liquid flow battery, the liquid flow battery management system includes a power supply and a control system of the metal deposition type liquid flow battery and an ultrasonic power supply and a control system.

[0054] The power supply of the liquid flow battery and its control system are used to control the charge and discharge parameters of the multi-pulse power supply and the charge and discharge parameters of the liquid flow battery, and adjust and optimize the real-time charge and discharge efficiency of the liquid flow battery stack based on the charge and discharge parameters and the discharge parameters;

[0055] The power supply of the metal deposition type liquid flow battery and the control system thereof are used to control the charging and discharging process of the metal deposition type liquid flow battery;

[0056] The power supply of the metal deposition type liquid flow battery and its control system are used to control the charge and discharge parameters of the multi-pulse power supply and the charge and discharge parameters of the liquid flow battery, adjust and optimize the morphology of the metal deposition layer on the negative electrode side and the real-time charging efficiency of the liquid flow battery stack based on the charging parameters of the liquid flow battery, and adjust and optimize the morphology of the electrolysis of the metal deposition layer on the negative electrode side and the real-time discharge efficiency of the liquid flow battery stack based on the discharge parameters of the liquid flow battery;

[0057] The ultrasonic power supply control system is used to control the alternating voltage output by the ultrasonic driving power supply, and based on the alternating voltage, controls the frequency, amplitude and phase of the corresponding ultrasonic vibration generated by the piezoelectric element, which is used to prepare a dense, uniform and more refined cathode side metal deposition layer for the metal deposition type liquid flow battery, and can drive the ultrasonic field to couple with the multi-pulse electric field, thereby improving the charging and discharging efficiency of the liquid flow battery.

[0058] A liquid flow battery optimization device disclosed in the present invention, by setting a conductive column and a piezoelectric element, controls the corresponding liquid flow battery charging and discharging and the discharge of an ultrasonic power supply based on a liquid flow battery management system, and applies ultrasonic waves to the central plate of the liquid flow battery stack, which is beneficial to removing the respective polarization phenomena on the positive and negative sides of the liquid flow battery stack, affecting the zinc metal deposition process of the negative electrode of the zinc-based liquid flow battery, and can prepare a zinc metal deposition layer with a tighter structure, thereby effectively utilizing the space of the negative electrode side reaction chamber in the liquid flow battery stack, and effectively avoiding battery failure due to the zinc dendrite deposition morphology piercing the ion exchange membrane in the liquid flow battery stack.

[0059] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present disclosure are shown in an exemplary and non-limiting manner, in which:

[0061] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0062] Figure 1 A schematic diagram of a liquid flow battery optimization device according to an embodiment of the present disclosure is shown;

[0063] Figure 2 A schematic diagram of the external circulation of a flow battery provided by an embodiment of the present disclosure is shown;

[0064] Figure 3a A schematic diagram of the structure of a battery stack provided by an embodiment of the present disclosure is shown;

[0065] Figure 3b The partial structure of the battery stack provided by the embodiment of the present disclosure is shown Figure 1 ;

[0066] Figure 3c The partial structure of the battery stack provided by the embodiment of the present disclosure is shown Figure 2 ;

[0067] Figure 3d A third schematic diagram of the local structure of a fuel cell stack provided by an embodiment of the present disclosure is shown;

[0068] Figure 4a The schematic diagram of the structure of the bipolar plate and electrode plate integrated structure provided by the embodiment of the present disclosure is shown. Figure 1 ;

[0069] Figure 4b The schematic diagram of the structure of the bipolar plate and electrode plate integrated structure provided by the embodiment of the present disclosure is shown. Figure 2 ;

[0070] Figure 4c A third structural schematic diagram showing the composition of the integrated structure of the bipolar plate and the electrode plate provided in an embodiment of the present disclosure;

[0071] Figure 4d A fourth structural diagram showing the composition of the integrated structure of the bipolar plate and the electrode plate provided in an embodiment of the present disclosure;

[0072] Figure 4e The schematic diagram of the structure of the bipolar plate and electrode plate integrated structure provided by the embodiment of the present disclosure is shown. Figure 5 ;

[0073] Figure 5 A schematic diagram of the two-dimensional structure of a bipolar plate with a honeycomb core structure according to an embodiment of the present disclosure is shown;

[0074] Figure 6 A schematic diagram showing an integrated structure of a bipolar plate and an electrode composed of a symmetrical conductive column and a piezoelectric element in an embodiment of the present disclosure is shown;

[0075] Figure 7A schematic diagram showing an integrated structure of a piezoelectric crystal-type asymmetric bipolar plate and an electrode according to an embodiment of the present disclosure is shown;

[0076] Figure 8 A schematic diagram showing an integrated structure of a piezoelectric film-based asymmetric bipolar plate and an electrode according to an embodiment of the present disclosure is shown;

[0077] Fig. 9 A line graph of variable current intermittent charging mode in an embodiment of the present disclosure is shown;

[0078] Fig.10 An energy curve diagram showing a common discharge mode and an optimized discharge mode of a flow battery in an embodiment of the present disclosure is shown;

[0079] Fig.11 A schematic diagram of a multi-pulse waveform output by an intelligent multi-pulse power supply in an embodiment of the present disclosure is shown;

[0080] Fig.12 A single group of waveform schematic diagrams of the multi-pulse power supply output in an embodiment of the present disclosure are shown;

[0081] Fig.13 A schematic diagram showing the effect of the rough electrode surface on the diffusion layer in the time dimension according to an embodiment of the present disclosure is shown;

[0082] Fig.14 A schematic diagram showing the active area and inert area on the electrode surface and their influence on the diffusion layer in an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0083] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0084] In order to explain the technical solution in detail, the piezoelectric principle in its technical background is first introduced.

[0085] The piezoelectric effect includes the positive piezoelectric effect and the inverse piezoelectric effect. The positive piezoelectric effect refers to the phenomenon of electric polarization due to deformation. When physical pressure is applied to the piezoelectric material, the electric dipole moment in the material will shorten due to compression. At this time, the piezoelectric material will generate equal positive and negative charges on the opposite surfaces of the material to resist this transformation in order to maintain its original state. This phenomenon of electric polarization due to deformation is called the positive piezoelectric effect. The positive piezoelectric effect is essentially the process of converting mechanical energy into electrical energy. The inverse piezoelectric effect refers to when an electric field (voltage) is applied to the surface of the piezoelectric material, the electric dipole moment will be elongated due to the action of the electric field. In order to resist the change, the piezoelectric material will stretch along the direction of the electric field. After the electric field is removed, the deformation of the piezoelectric material disappears. This process of mechanical deformation through the action of the electric field is called the inverse piezoelectric effect, or electrostriction. The inverse piezoelectric effect is essentially the process of converting electrical energy into mechanical energy. The coefficients in the positive piezoelectric effect and the inverse piezoelectric effect are equal, and materials with the positive piezoelectric effect must have the inverse piezoelectric effect. These two effects can be expressed by the following formula: P = d·T, S = d·E, where P is the polarization intensity of the crystal, the unit is C / m2, T is the stress, the unit is N / m2, d is the piezoelectric constant, the unit is C / N or m / V, S is the strain, and E is the electric field intensity vector, the unit is V / m.

[0086] In the direct piezoelectric effect, when a piezoelectric crystal is subjected to an external force in a fixed direction, electric polarization occurs inside the crystal, and charges of opposite signs are generated on the surfaces of two crystals. When the external force is removed, the crystal returns to an uncharged state. When the direction of the external force changes, the polarity of the charge on the surface of the crystal also changes. The amount of charge generated by the crystal is proportional to the magnitude of the external force. In the inverse piezoelectric effect, when an alternating electric field is applied to a piezoelectric crystal, mechanical deformation of the piezoelectric crystal will occur. Transmitters made using the inverse piezoelectric effect can be used in electroacoustic and ultrasonic engineering.

[0087] Based on the above-mentioned piezoelectric principle, an embodiment of the present invention provides a liquid flow battery optimization device. Figure 1 A schematic diagram of a flow battery optimization device according to an embodiment of the present disclosure is shown. Figure 1 As shown, the liquid flow battery optimization device of the embodiment of the present disclosure includes: a liquid flow battery stack and an embedded ultrasonic sound-generating device, wherein the liquid flow battery stack is composed of liquid flow battery cells electrically connected in series; the ultrasonic sound-generating device is composed of an ultrasonic driving power supply and a piezoelectric element.

[0088] In the disclosed embodiment, the liquid flow battery unit includes an integrated component of a bipolar plate and an electrode plate, an ion exchange membrane, and an electrode frame. The integrated component of the electrode plate includes a negative electrode plate and / or a positive electrode plate. Conductive columns are evenly arranged between the bipolar plate and the negative electrode plate and the positive electrode plate. The bipolar plate and the negative electrode plate and the positive electrode plate are electrically connected based on the evenly distributed conductive columns to achieve electrical series connection of the liquid flow battery unit.

[0089] In the disclosed embodiment, the liquid flow battery management system controls the (intelligent) multi-pulse power supply and the ultrasonic drive power supply respectively. Among them, the positive and negative electrodes of the (intelligent) multi-pulse power supply are electrically connected to the positive and negative current collectors of the liquid flow battery stack respectively; the positive and negative electrodes of the ultrasonic drive power supply are electrically connected to the piezoelectric elements on the positive and negative sides of the electrode assembly through the hollow structure of the bipolar plate in each liquid flow battery unit in the liquid flow battery stack. The parameters of the (intelligent) multi-pulse power supply and the ultrasonic drive power supply are set by the liquid flow battery management system to complete the coupling of the electric field and the ultrasonic field in the liquid flow battery stack, and act together on the positive and negative electrodes and their corresponding electrolyte interfaces. Through the (symmetrical or asymmetrical) uniform arrangement of the conductive columns and piezoelectric elements on the positive and negative sides of the electrode assembly, the reaction interface diffusion layer is homogenized, and various polarization phenomena occurring at the interface between the electrode and the electrolyte are alleviated, thereby improving the charge and discharge efficiency of the liquid flow battery. For liquid flow batteries with metal deposits on the cathode side, the morphology of the metal deposits during the charge and discharge process of the liquid flow battery can be improved, thereby reducing the possibility of the dendrites of the metal deposits puncturing the ion exchange membrane in the liquid flow battery. Among them, a switch array is used to control the switch of the ultrasonic generating signal entering each electrode assembly. During the normal charge and discharge process of the liquid flow battery, the piezoelectric elements in each electrode assembly work normally. During the maintenance of the liquid flow battery, the piezoelectric elements can be turned on for the problematic liquid flow battery unit for directional maintenance, and the other switches are in the disconnected state.

[0090] In the disclosed embodiment, the piezoelectric element is divided into a piezoelectric crystal or a piezoelectric film, the piezoelectric crystal or the piezoelectric film is arranged on the periphery of the conductive column, the piezoelectric element is arranged between the bipolar plate and the positive plate and / or the negative plate, and the piezoelectric element is powered by an ultrasonic driving power supply so that the piezoelectric element performs ultrasonic vibration, which acts on the bipolar plate, the negative plate and / or the positive plate, wherein the relevant parameters of the ultrasonic vibration include the frequency, amplitude and phase of the vibration. A resin material resistant to corrosion by the electrolyte is filled between the bipolar plate and the electrode plate to prevent the conductive column and the piezoelectric element from contacting the electrolyte, and the resin material is also used to fix the relative position between the piezoelectric element and the conductive column.

[0091] In the embodiments of the present disclosure, piezoelectricity exists in natural or synthetic materials. Most piezoelectric materials used in engineering applications are artificially synthesized. For example, lead-zinc-titanium compounds (PbZrTiO 3 —PbTiO 3or PZT), lead zirconate titanate, barium titanate, barium strontium titanate (BaSTO), lead lanthanum zirconate titanate (PLZT), lithium sulfate, polyvinylidene fluoride (PVDF) and its copolymers (PVDF), etc. Piezoelectric materials can be divided into polymer materials and ceramic materials according to their structure. Polymer piezoelectric materials, such as copolymers of polyvinylidene fluoride (PVDF) after polarization treatment, have found a variety of uses in industrial applications, such as ultrasonic transducers, hydrophones, microphones, and vibration damping. In contrast, ceramic (PZT) materials with higher stiffness and higher electromechanical coupling coefficients have excellent performance and can be optimized to meet specific applications by properly adjusting the titanate ratio. The mechanical properties of ceramic (PZT) materials make them suitable for various electromechanical transducers, such as converting mechanical shock or pressure into electrical energy; for example, piezoelectric ceramics are used in accelerometers and pressure sensors; for example, piezoelectric ceramics are used in acoustic and ultrasonic transducers to generate high-frequency sound waves for different measurement applications; for example, piezoelectric ceramics are used in the actuator structure of pneumatic and hydraulic valves.

[0092] In the disclosed embodiment, the piezoelectric crystal can be a piezoelectric ceramic. The preparation of the piezoelectric ceramic is mainly to prepare a ceramic powder with piezoelectric properties by using powder metallurgy or chemical synthesis; the ceramic powder is mixed with an organic adhesive, and parts of the desired shape are made by pressing, molding and other processing techniques; the molded parts are placed in a furnace for high-temperature sintering to form a dense ceramic embryo; the sintered ceramic embryo is placed in a high-voltage electric field for polarization treatment to give it piezoelectric properties and other standard processes to complete, wherein the material of the piezoelectric crystal includes at least one of the following: lead-zinc-titanium compounds, lead zirconate titanate, barium titanate, barium strontium titanate, lead lanthanum zirconate titanate, lithium sulfate. The preparation methods of piezoelectric films include: sol-gel method (Sol-Gel), vacuum evaporation method, sputtering method (RF magnetron sputtering method, DC magnetron sputtering method), chemical vapor deposition method and pulsed laser deposition (PLD), electrochemical plating and other preparation methods. Most thin film deposition methods are carried out under high vacuum conditions. The materials of piezoelectric films include, but are not limited to: polyvinylidene fluoride (PVDF) piezoelectric films, polyvinylidene fluoride-poly (3,4-ethylenedioxythiophene)-poly (styrene sulfonic acid) (PVDF / PEDOT / PSS) mixed piezoelectric films, aluminum nitride piezoelectric films, doped aluminum nitride piezoelectric films, carbon-based piezoelectric films, barium titanate (BaTiO 3 ) A composite piezoelectric film between one or more of the piezoelectric films. Afterwards, in order to obtain the piezoelectricity of the film, the film needs to be uniaxially stretched to obtain a stretched structure, and then heated to 80-110°C and polarized to obtain a film structure with piezoelectricity, wherein the material of the piezoelectric film includes at least one of the following: polyvinylidene fluoride, polyvinylidene fluoride copolymer, polymer of 3,4-ethylenedioxythiophene monomer, sodium polystyrene sulfonate, aluminum nitride, and carbon-based.

[0093] In the embodiment of the present disclosure, the positive and negative electrodes are located on two opposite surfaces of the piezoelectric element where charge distribution is generated during the piezoelectric effect, and are assembled integrally with the piezoelectric element. In this process, the processes used include but are not limited to: a combination of one or more of a film pressing method, a film coating method, a film filtration method, and a film spin coating method.

[0094] In the disclosed embodiment, the flow battery stack is formed by stacking and fastening a plurality of battery cells in the manner of a filter press, and a current collector and an end plate are respectively installed at both ends. The end plate cooperates with fasteners to play the role of (sealing) clamping the battery cells. The current collector is physically connected to the positive and negative electrodes at both ends of the battery stack, and the battery cells in the battery stack are connected in series through the positive and negative electrodes on both sides of the center plate. During the charging process of the battery stack, the current collector distributes the current from the positive and negative electrodes of the battery stack to each battery cell inside the battery stack; during the discharge process of the battery stack, current is generated between the positive and negative electrodes of each battery cell, and is collected and transmitted through the current collector. The battery cell in the battery stack consists of an ion exchange membrane, and electrodes, electrode frames, sealing pads (surfaces) and bipolar plates (center plates) symmetrically arranged on both sides thereof. The two sides of the bipolar plate (center plate) are physically connected to the positive and negative electrodes respectively. Among them, the ion exchange membrane forms two relatively independent chambers with the positive and negative electrodes, the electrode frame, and the sealing pad (surface), respectively. During the charge and discharge process of the fluid battery stack, the first and second electrolyte solutions flow through the two chambers of their respective battery cells and undergo electrochemical redox reactions at the interfaces of the positive and negative electrodes.

[0095] Figure 2 This is a schematic diagram of the external circulation of a liquid flow battery, in which the liquid flow battery includes a battery stack 100, a circulation pump 21, a filter 22 for a cathode electrolyte solution, a filter 23 for an anode electrolyte solution, a valve 24, a storage tank 25 for a cathode electrolyte solution, a storage tank 26 for an anode electrolyte solution, an insulation layer 27, a thermocouple temperature sensor 28, a flow sensor 29, a pressure transmitter 30 and an electric heater 31.

[0096] Figure 3a It is the structural diagram of the battery stack. Figure 3b , Figure 3c and Figure 3d It is a schematic diagram of the local structure of the battery stack, which includes: bipolar plate 1, negative electrode plate 2, positive electrode plate 3, current collecting plate 11, positive electrode frame 13, ion exchange membrane 14, manifold 15 in the negative electrode frame, manifold 16 in the positive electrode frame, battery stack negative electrode main channel 17, battery stack positive electrode main channel 18, sealing surface 19, and battery stack 100.

[0097] Combination Figure 2 , Figure 3a , Figure 3b , Figure 3c and Figure 3dAs shown, the external circulation of the flow battery and the internal structure of the flow battery stack 100, wherein Figure 3d It is the basic structure of the liquid flow battery unit 40. A manifold (distribution flow channel) is designed in the positive and negative plate frames of the liquid flow battery unit 40, that is, a manifold 15 (distribution flow channel) in the negative frame and a manifold 16 (distribution flow channel) in the positive frame, so that the first electrolyte solution 4 and the second electrolyte solution 5 can enter and flow out of the positive and negative electrode chambers of each battery unit 40 from the positive main channel 18 and the negative main channel 17 of the battery stack from bottom to top, and electrochemical oxidation-reduction reactions occur with the interfaces of the positive and negative electrodes. The positive and negative main channels of the battery stack 100 can be formed in the battery stack 100 by the internal structure of the positive electrode frame (positive electrode frame 13) and the negative electrode frame (negative electrode frame 12) of the liquid flow battery unit 40, or can be formed outside the battery stack 100 by an independent main pipeline and a manifold structure connecting the positive and negative electrode frames of the liquid flow battery unit 40. The sealing surface 19 of each unit of the flow battery is used to prevent the first and second electrolyte solutions from leaking from the contact surface between the bipolar plate 1 (center plate) and the electrode frame, and the contact surface between the ion exchange membrane 14 and the electrode frame. The sealing surface 19 can be provided by clamping the sealing gasket under pressure, or by laser welding, ultrasonic welding, etc., in combination with the hot pressing and heat sealing process of the hot melt film, and the hot pressing and heat sealing process is preferably used as an effective sealing process. The hot melt film used should be resistant to strong acid and strong alkali corrosion, and its melting point should be lower than the softening temperature of the electrode plate.

[0098] FIG4 shows a schematic diagram of the composition and changes of the integrated structure of the bipolar plate (center plate) and the electrode plate in the embodiment of the present disclosure, as shown in FIG4: 1. Bipolar plate (center plate) 2. Negative electrode plate 3. Positive electrode plate 4. First electrolyte solution 5. Second electrolyte solution 6. Conductive block for fixing the electrode plate and the bipolar plate 7. First porous plate 8. Second porous plate 9. Three-dimensional fiber composite structure. Among them, on both sides of the ion exchange membrane, the first and second electrolyte solutions flow through the two chambers of their respective battery cells respectively, and undergo electrochemical redox reactions with the interfaces of the positive and negative electrodes. On the premise that the spatial dimensions of the respective chambers of the battery cells meet the relevant design requirements, by increasing the contact surface area between the positive and negative electrodes and their respective electrolyte solutions; increasing the surface area of ​​the positive and negative electrodes themselves; and increasing the mass transfer efficiency of the electrolyte solution flowing through the positive and negative electrode regions, the reaction points of the electrochemical reaction during the charge and discharge process can be fully improved.

[0099] In the disclosed embodiment, the positive and negative electrode plates in FIG4(a) are in close contact with the bipolar plate, and are fixedly attached and electrically connected to the bipolar plate. In FIG4(b), a conductive block is used as a channel for electrical connection between the bipolar plate and the positive and negative electrode plates, thereby completing the integrated structure of the bipolar plate and the positive and negative electrode plates. The sealing surfaces within the flow battery cell and the sealing surfaces between the flow battery cells are used to isolate the electrolyte solution flowing through the respective chamber spaces of adjacent battery cells. The electrodes in the battery stack require a certain amount of deformation, and the conductive block used in FIG4(b) can provide the overall rigidity and electrical connection requirements of the integrated structure of the bipolar plate (center plate) and the electrode plate. Compared with FIG4(a), FIG4(b) shows that the electrochemical reaction area between the electrode plate and the electrolyte solution is changed from the original surface area S1 (S1') on one side of the electrode (strictly speaking, one side of the bipolar plate is covered by the electrode plate, and a part of the surface area is still in contact with the electrolyte solution. For the sake of convenience, this part of the surface area is ignored) to the surface area S1+S2 (S1'+S2') of the two electrode plates and the surface area S3 (S3') on one side of the bipolar plate (strictly speaking, it is necessary to remove the area covered by the conductive block in the surface areas S2 and S3, and add the body surface area of ​​the conductive block in contact with the electrolyte solution. For the sake of convenience, it is abbreviated as the sum of these three surface areas); FIG4(c) uses a first porous plate made of porous metal material or porous carbon material as the positive and negative porous electrodes instead of the original positive and negative electrode plates, and the porous electrodes are directly fixed and electrically connected to the conductive blocks. Compared with FIG. 4(a), FIG. 4(c) shows that the electrochemical reaction area between the electrode plate and the electrolyte solution is changed from the original surface area S1 (S1') on one side of the electrode to the specific surface area S4 (S4') of the porous electrode and the surface area S3 (S3') on one side of the bipolar plate; FIG. 4(d) shows that the second porous plate made of porous metal material or porous carbon material is used as the positive and negative porous electrodes to be fixedly connected and electrically connected to the original positive and negative electrode plates. Compared with FIG. 4(a), FIG. 4(d) shows that the electrochemical reaction area between the electrode plate and the electrolyte solution is changed from the original surface area S1 (S1') on one side of the electrode plate to the specific surface area S4 (S4') of the porous electrode, the surface area S2 (S2') on one side of the electrode plate and the surface area S3 (S3') on one side of the bipolar plate (strictly speaking, the other side of the electrode plate is covered by the porous electrode, but there is still a surface in contact with the electrolyte solution. For convenience, this part of the surface area is ignored here). Compared with Figure 4(c), Figure 4(d) not only provides more electrochemical reaction area, but also provides better rigidity requirements for the integrated structure of the bipolar plate and the positive and negative electrode plates, so the solution of Figure 4(d) is better. In Figure 4(e), a three-dimensional fiber composite structure is placed outside the positive and negative electrode plates.Compared with FIG. 4(b), FIG. 4(e) shows that the electrochemical reaction area between the electrode plate and the electrolyte solution is basically the same, but due to the presence of the three-dimensional fiber composite structure (at this time, the composite structure is not fixedly connected and electrically connected to the electrode plate, and there is a gap between the composite structure and the electrode plate), the flow and mixing mode of the electrolyte near the surface area S1 (S1') on one side of the electrode plate, and the contact mode between the active material and the electrode plate are changed and strengthened, which is helpful for promoting the electrochemical reaction between the contact interface between the electrode plate and the electrolyte. Therefore, the scheme of FIG. 4(e) is optimized compared with FIG. 4(b); the composite structure can be formed by three-dimensional weaving of polymer-based fiber materials. At this time, the composite structure only has structural characteristics. Multiple layers of three-dimensional fiber structural units with different structural forms are arranged in sequence along one direction to form a functional structure similar to a static mixer. When a fiber material with special functions is used in the composite structure, such as a fiber material with electrical conductivity, thermal conductivity, heat storage, redox (energy storage) and other characteristics, the composite structure is fixedly connected and electrically connected to the electrode plate to give the flow battery other functional characteristics. In addition, as shown in Figure 4(c), Figure 4(d), and Figure 4(e), the porous electrodes and three-dimensional fiber composite structures used do not necessarily need to be arranged completely symmetrically on both sides of the bipolar plate, but can be freely matched and structurally and parameterized to meet the needs of the electrochemical reaction characteristics of the positive and negative electrodes in a certain flow battery system, as well as the matching relationship between the amount of active substances participating in the electrochemical reaction of the positive and negative electrodes. From the internal structure of the flow battery stack, adding porous electrodes or three-dimensional fiber composite structures with elasticity, certain compression and reset functions on both sides of the ion exchange membrane helps to support the ion exchange membrane and avoid internal leakage of the stack caused by displacement of the ion exchange membrane.

[0100] In the disclosed embodiment, the bipolar plate may adopt a honeycomb core structure. Figure 5 is a schematic diagram of the two-dimensional spatial structure of a bipolar plate with a honeycomb core structure, such as Figure 5As shown: 1. Bipolar plate (center plate) with honeycomb core structure 2. Negative electrode 3. Positive electrode 4. Phase change filling material, the regular hexagonal plane of the honeycomb core is parallel to the plane of the ion exchange membrane. When the positive and negative electrodes are metal, the bipolar plate (body and panel) is made of metal, and the metal should be resistant to chemical and electrochemical corrosion, such as stainless steel; when the positive and negative electrodes are prepared by fully mixing, thermally curing, and high-temperature pyrolysis of porous carbonaceous materials and thermosetting resins, the bipolar plate (body and panel) is made of porous carbonaceous materials, such as carbon paper. The geometric parameters of the bipolar plate with a honeycomb core structure include: the overall (body + panel) structure thickness of the honeycomb core δ1, the panel thickness δ2, the cell side length a, the wall thickness b, etc. This series of parameters determines the heat transfer and heat dissipation characteristics of the honeycomb core structure bipolar plate, and also determines the conductive properties of the honeycomb core structure bipolar plate, which is feasible for experimental optimization. In order to increase the heat capacity of the bipolar plate, a phase change material is filled inside the honeycomb core structure, wherein the phase change material absorbs or releases a certain amount of latent heat of phase change during the phase change process without a significant change in its own temperature. During the charging and discharging process of the battery stack, when local overheating occurs in the positive and negative electrode structures and their interfaces with the electrolyte solution, the overheat can be dissipated, and the temperature fluctuation of the combined structure formed by the bipolar plate and the positive and negative electrodes can be suppressed. When selecting the phase change material, attention should be paid to calculating whether the latent heat of the phase change material meets the requirements according to the load heat consumption and changes of the combined structure formed by the bipolar plate and the positive and negative electrodes during the charging and discharging of the liquid flow battery, the heat flow changes at the interface between the electrode outside the heat dissipation surface and the electrolyte solution, and the temperature control accuracy requirements; the solid-liquid phase change point should generally be selected within the temperature control threshold range near the controlled object, that is, the above-mentioned combined structure and its interface with the electrolyte solution. At the same time, attention should also be paid to the safety issues that may be caused by the expansion of the phase change material. At the same time, the hollow two-dimensional space structure of the bipolar plate helps the propagation of ultrasonic vibrations in the integrated structure of the bipolar plate and the electrode plate.

[0101] Figure 6 A schematic diagram of an integrated structure of a bipolar plate and an electrode consisting of a symmetrical conductive column and a piezoelectric element in an embodiment of the present disclosure is shown. Figure 6 As shown, the bipolar plate and electrode integrated structure is used to generate a combination of uniform electric field and ultrasonic field at the interface between the electrode and the electrolyte, wherein the conductive column is electrically connected to the bipolar plate and the electrode plate to form the bipolar plate and electrode integrated structure. Figure 6 In (a), a cylindrical piezoelectric crystal module is used to surround the conductive column, so that the ultrasonic field generated by the piezoelectric crystal and the electric field of the conductive column act together on the electrode plate to ensure that the diffusion layer at the contact interface between the electrode plate and the electrolyte is evenly distributed. The piezoelectric crystal is wrapped with an insulating substrate; Figure 6In (b), a sheet assembled with a piezoelectric film is used to wrap the conductive column, so that the ultrasonic field generated by the piezoelectric film and the electric field of the conductive column act together on the electrode plate to ensure that the diffusion layer at the contact interface between the electrode plate and the electrolyte is evenly distributed. Whether it is a piezoelectric crystal or a piezoelectric film sheet, it is necessary to use a wire to connect the positive and negative electrodes of the piezoelectric body, and change the frequency of the power supply to cause the vibration of the piezoelectric body, thereby generating ultrasonic vibration. Based on the hollow two-dimensional space structure of the above-mentioned bipolar plate, the relevant wires are pre-buried, pass through the hollow structure of the bipolar plate, and extend out of the battery stack structure to be connected to an external ultrasonic drive power supply. The outside is sealed with a sealing surface to isolate the electrolyte on the positive and negative sides.

[0102] In the embodiment of the present disclosure, the piezoelectric crystal is provided with a positive electrode and a negative electrode, the positive electrodes of the plurality of piezoelectric crystals are connected together separately, the negative electrodes are connected together separately, and the upper and lower surfaces are arranged in unison to form a shared positive electrode and a shared negative electrode structure; the positive electrode and the negative electrode of the piezoelectric film are arranged on both sides of the film, and the plurality of piezoelectric films are stacked so that the positive electrode and the negative electrode are connected in series or in parallel to form a piezoelectric film integrated structure, and the shared positive electrode and shared negative electrode structure or the piezoelectric film integrated structure in at least one of the liquid flow battery cells are connected in series or in parallel and connected to an ultrasonic driving power supply through a lead, and the ultrasonic driving power supply is connected to the positive and negative electrodes of the integrated structure composed of piezoelectric crystals or piezoelectric films in each liquid flow battery cell based on a distributed wire link, and controls the magnitude of the alternating voltage transmitted to the integrated structure composed of piezoelectric crystals or piezoelectric films in each liquid flow battery cell, wherein the alternating voltage is used to control the frequency, amplitude and phase of the corresponding ultrasonic vibration generated by the piezoelectric crystal and the piezoelectric film, and generate an ultrasonic field to act on the contact interface between the electrode and the electrolyte in each of the liquid flow battery cells, so that the active material in the diffusion layer is evenly distributed.

[0103] In the embodiment of the present disclosure, the piezoelectric elements are evenly distributed between the positive plate and / or the negative plate and the bipolar plate, and the conductive columns are symmetrically or asymmetrically distributed around the bipolar plate, wherein: Figure 7 It is a schematic diagram of an integrated structure of a piezoelectric crystal asymmetric bipolar plate and electrode. Figure 8It is a schematic diagram of a piezoelectric film-type symmetrical bipolar plate and electrode integrated structure. The conductive column makes the active material in the diffusion layer of the contact interface between the corresponding electrode and the electrolyte evenly distributed. The piezoelectric element is set based on the corresponding setting of the conductive column, which is used to improve the uniformity and consistency of the interface between the electrode plate and the electrolyte in the liquid flow battery unit. During the charge and discharge process of the liquid flow battery, the electric field generated by the bipolar plate and the electrode plate integrated assembly acts on the positive plate and / or the negative plate together. The external power supply system applies the electric field to each liquid flow battery unit in the liquid flow battery stack through the positive and negative current collectors at both ends of the liquid flow battery stack, and couples with the ultrasonic field generated by the piezoelectric element set in the liquid flow battery unit, and acts on the interface between each electrode and the electrolyte of the liquid flow battery unit; or the position of the piezoelectric element is set according to the coupling relationship between the ultrasonic field when the piezoelectric element is working and the electric field generated when the liquid flow battery stack is working.

[0104] Fig. 9 A line chart of the variable current intermittent charging method in the embodiment of the present disclosure is shown. Fig. 9 As shown, in the embodiment of the present disclosure, Fig. 9 (a) The constant current charging and constant voltage charging during the time period T2' to T4' are changed to Fig. 9 (b) The variable current intermittent charge (VCIC) method can be changed to Fig. 9 (c) The variable voltage intermittent charging method (VVIC) is used. Its characteristics are that the constant current charging section is changed to a voltage-limited variable current intermittent charging section. In the above time period, each section in the early stage of charging adopts the variable current intermittent charging method to ensure that the charging current is increased and more charging capacity is obtained. In the later stage of charging, a constant voltage charging section is used to obtain an overcharge amount and restore the flow battery to a fully charged state. By intermittently stopping charging, the gas evolution and concentration polarization phenomena in the flow battery are alleviated, and the ohmic polarization phenomenon is temporarily eliminated. The specific parameters of intermittent charging can be optimized by relevant experiments; or the constant current charging section can be changed to a variable voltage intermittent charging method. The variable voltage method is more in line with the charging curve of the optimal charging. In each constant voltage charging stage, due to constant voltage charging, the charging current naturally decreases according to the exponential law, which is in line with the characteristic that the battery current acceptance rate gradually decreases with the charging process. By Fig. 9 (a), 7(b), and 9(c) show that, assuming that the amount of electricity charged during this period is the same, then Fig. 9 (b) the time period used is shorter, Fig. 9 (c) The time period used is longer.

[0105] In the embodiments of the present disclosure, the liquid flow battery has intermittent, frequently fluctuating, and staged operating conditions during the actual discharge process. Intermittent discharge is helpful for the liquid flow battery to recover polarization loss under high discharge current density, and is helpful for improving the battery discharge capacity and the battery coulombic efficiency.

[0106] Fig.10 The energy curve diagram of the common discharge mode and the optimized discharge mode of the flow battery in the embodiment of the present disclosure is shown as follows: Fig.10 As shown, Fig.10 (a) is the current-time curve. Fig.10 (b) is the voltage-time curve. Fig.10 (c) is the power-time curve. Fig.10 (d) is the intermittent discharge optimization curve. Among them, the commonly used discharge modes of flow batteries are constant current discharge, constant resistance discharge and constant power discharge. In the constant resistance discharge mode, the current and voltage drop trends are the same. Since P = V 2 / R, the power decreases with the square of the voltage, and the speed is faster. In this discharge mode, in order to ensure that there is still the required power output at the termination voltage, the current and power level at the beginning of the discharge will exceed the required minimum value. If the battery is discharged at a current higher than the required current, the capacity will be discharged quickly, resulting in a shortened battery life; in the constant current discharge mode, the current is maintained at such a level that the power output at the termination potential is equal to the level that meets the performance requirements of the device. Therefore, the discharge current and power output are lower than the constant resistance mode, the average current passing through the battery is low, and the discharge time or service life is longer; in the constant power discharge mode, since I = P / V, the current increases with the decrease of the discharge voltage, and the average discharge current is higher at this time, and the discharge time is shorter. If we only look at the impact of the discharge method on the battery, the discharge curve corresponding to the constant power discharge method is not flat, but during the use of the battery, the external load may need to work at a constant power, and the resistance values ​​of different external loads are different, so sometimes it is still necessary to use this method to discharge the load. Constant resistance discharge requires the external load resistance to be a constant value, which is not consistent with the actual discharge scenario (the discharge external load is random). It can be seen that the choice of discharge mode depends on the nature of the load device. When confirming the discharge termination voltage value and the power value required to be output when discharging to the termination voltage, you can select a suitable current value for constant current discharge, or select a suitable external load resistance value for constant resistance discharge, or select a suitable power value for constant power discharge. In the actual discharge process of the flow battery, there are intermittent, frequent fluctuations, and staged working conditions. Intermittent discharge is helpful for the flow battery to recover polarization loss at high discharge current density, and is helpful for improving the battery discharge capacity and the coulomb efficiency of the battery. Through the coordination of the energy management system, it is more reasonable to choose a suitable discharge method based on the understanding of the power output requirements of the flow battery. The relevant test device should consider this part of the function, preset the discharge strategy (system) under different scenarios, and optimize the parameters of the specific discharge method under the strategy (system). In this process, the intermittent discharge method can be appropriately used, that is, from the perspective of the discharge strategy, in each power consumption interval, intermittent high-rate discharge is used instead of constant low-rate discharge, and better discharge efficiency is obtained. The specific parameters of intermittent discharge (such as the duty cycle of discharge time, the range of discharge current value, etc.) and the ratio between high and low rate discharge can be optimized by relevant experiments, provided that the discharge time is shortened, the discharge efficiency is improved, and the overall discharge capacity of the battery is maintained.

[0107] In the embodiment of the present disclosure, the intelligent multi-pulse power supply can be used to prepare metal-based composite materials by electrodeposition. Usually, single metals such as Ni, Cu, and Co are used as the matrix metal, and SiC, SiO 2 、Al 2 O 3The composite electrodeposition of particles such as MgO and NiO as the second phase has been developed to the electrodeposition of various alloys and multiple particles that can meet special functional requirements. The particle-reinforced metal matrix composites are prepared by periodic commutation pulse current, which has better performance than the composite materials prepared under direct current, thereby broadening the application range of metal matrix composites. In addition, the second phase particles selected by traditional composite electrodeposition technology are mostly limited to the micron level, with large particle size, poor suspension ability, and rough surface of the deposited layer. In addition, the particles are easy to clog the filter element during the production process, which limits the necessary circulation filtration process in the electrodeposition. The matrix metals of high hardness and wear-resistant metal matrix composites are mostly Ni-based, Ni-based alloys and Cr-based. The particles used for composites are Al 2 O 3 、ZrO 2 、SiO 2 、SiC、TiC、TiO 2 、WC、Si 3 N 4 , B 4 C、ZrB 2 And diamond, etc. Through the electrodeposition method, these particles are dispersed in the metal matrix composite material, which can improve the microhardness and wear resistance of the composite material, and at the same time have good high temperature resistance and oxidation resistance. The matrix metal of the corrosion-resistant metal matrix composite material is mainly Ni-based, Cr-based, Cu-based and Zn-based. The added particles are mainly ZrO 2 、SiC、TiO 2 、SiO 2 、Al 2 O3, B 4 C, etc. The matrix metals of self-lubricating metal matrix composite materials are mainly Ni, Cu, Ag, Pb, Au, Co, etc., and the added particles are mainly MoS 2 , BN, WS 2 , graphite and graphite fluoride (CF) n and polytetrafluoroethylene (PTFE), etc. The matrix metals of metal-based composite materials with electrocatalytic activity are mostly Ni, Pt, Ni-P, Ni-Mo, PbO 2 、Co 3 O 4 , polypyrrole (PPy), polyaniline (PAN), polythiophene (PTh), etc. The added particles are mainly ZrO 2 、TiO 2 、RuO 2 ,PTFE,SnO 2 The matrix metals of metal-based composite materials with electrical contact function are mainly Au, Ag, etc., and the added particles are mainly diamond, WC, TiC, SiC, etc.

[0108] Fig.11 FIG. 4 shows a schematic diagram of a multi-pulse waveform output by an intelligent multi-pulse power supply in an embodiment of the present disclosure. Fig.11 As shown, the multi-pulse waveform output by the intelligent multi-pulse power supply in the embodiment of the present disclosure can be decomposed into multiple independent waveforms, including a single pulse waveform and a double pulse waveform, wherein the intelligent multi-pulse power supply can cyclically output a multi-pulse current waveform combination of dozens of groups of unidirectional or periodic commutation pulse currents with different parameters such as pulse width, frequency, amplitude, commutation time, and working time.

[0109] In the disclosed embodiment, the multi-pulse power supply is a pulse power supply that can be used to prepare nano-composite materials. During use, multiple groups of pulse currents with different parameters such as pulse width, frequency, amplitude, commutation time, working time, etc. or periodic commutation pulse currents can be cyclically output. The composite materials or components obtained using pulse currents with different parameters are different, so selecting appropriate pulse currents with different parameters to alternately perform electrodeposition can effectively improve the cathode polarization degree of the electrolyte, increase the cathode polarization potential and the probability of nucleus formation, refine the grains, and then obtain nano-sized metal-based nano-composite materials with excellent performance, providing a powerful means for the research and development and production of nano-composite electrodeposition technology.

[0110] In the disclosed embodiment, the liquid flow battery stack uses a multi-pulse power supply for charging and discharging, and acts on the positive and negative electrodes of each liquid flow battery unit through the positive and negative current collectors at both ends of the liquid flow battery stack and the internal structure of the liquid flow battery stack, respectively, to affect the positive and negative electrodes and their electrolyte interfaces. Among them, the multi-pulse power supply includes a single-pulse power supply and a double-pulse power supply, and the two power supplies are combined or work separately according to the actual charging and discharging conditions of the liquid flow battery stack, and act on the positive and negative current collectors of the liquid flow battery stack.

[0111] In the embodiment of the present disclosure, corresponding single pulse parameters are set according to the single pulse power supply, including: pulse frequency, pulse duty cycle and pulse peak electric energy, wherein the pulse frequency is calculated based on the pulse on-off period; the pulse peak electric energy is calculated based on the pulse duty cycle and the pulse average electric energy, and the pulse power supply charging and discharging parameters of the single pulse power supply are set based on the pulse frequency, pulse duty cycle and pulse peak electric energy.

[0112] In the embodiment of the present disclosure, the corresponding dual pulse parameters are set according to the dual pulse power supply, including: forward and reverse pulse frequencies, forward and reverse pulse duty cycles, and forward and reverse pulse peak electrical energies. Among them, the forward and reverse pulse frequencies are calculated based on the forward pulse on-off cycle and the reverse pulse on-off cycle; the forward and reverse pulse peak electrical energies are calculated based on the percentage of the forward pulse time and the reverse pulse time in the pulse working cycle, the average electrical energy of the forward pulse time, the average electrical energy of the reverse pulse, and the forward and reverse pulse duty cycles; the pulse power supply charge and discharge parameters of the dual pulse power supply are set based on the positive and reverse pulse frequencies, the positive and reverse pulse duty cycles, and the positive and reverse pulse peak electrical energies.

[0113] In the disclosed embodiment, the input or output electric energy includes: pulse current, pulse voltage and pulse power. When the pulse power supply is used to charge the liquid flow battery system, different pulse electric energies and their combinations are set based on the pulse power supply charging parameters to improve the charging efficiency of the liquid flow battery system; based on the average pulse electric energy, peak pulse electric energy density and the positive and reverse pulse duty ratios during the discharge process, the discharge efficiency of the liquid flow battery system is controlled and improved.

[0114] Fig.12 A single set of waveform diagrams of the multi-pulse power supply output in the embodiment of the present disclosure is shown, such as Fig.12 As shown, Fig.12 -(a) is a single pulse waveform, Fig.12 -(b) is a double pulse waveform.

[0115] In the embodiment of the present disclosure, p is the peak current; j m is the average current; t on is the pulse on time; t off is the pulse off time; T is the pulse on-off period. The relevant calculations of single pulse parameters are as follows:

[0116] (1) Pulse frequency. Pulse frequency is generally represented by f, which is calculated from the pulse on-off period T. It cannot be set to a number and is expressed as:

[0117]

[0118] (2) Pulse duty cycle. The pulse duty cycle is the percentage of the pulse on time to the entire pulse period, generally expressed as γ:

[0119]

[0120] (3) Pulse peak current. Pulse peak current j p , average current j m There is the following relationship between the duty cycle γ:

[0121]

[0122] +j in the picture p is the forward pulse peak current, -j p is the reverse pulse peak current; T is the pulse on-off period, T = t on +t off (Formula 4); T F is a set of forward pulse working time, T F =nT (Formula 5), ​​T R is a reverse pulse working time, T R = -nT (Formula 6); TF +T R is a cycle of forward and reverse pulse switching (when a multi-pulse power supply is used for electrodeposition, T F >T R ). The relevant calculations of the double pulse parameters are as follows:

[0123] (1) Forward and reverse pulse frequency. The forward and reverse pulse frequencies are calculated by their respective pulse on-off cycles T, and cannot be set. They are correctly displayed when each group is working, and are expressed as:

[0124]

[0125] (2) Forward and reverse pulse duty ratio. The forward and reverse pulse duty ratios are the respective pulse conduction time t on The percentage of the entire pulse on-off period T is expressed as:

[0126]

[0127] (3) Forward and reverse pulse peak current. The forward and reverse pulse peak current of the double pulse j p Divided by the average current j m In addition to being related to the duty cycle γ, it is also related to the percentage of each working time in the entire positive and negative pulse working cycle. The calculation formula is expressed as:

[0128]

[0129] In the embodiments of the present disclosure, under the premise of maintaining the average current density, the peak current density is increased by changing the duty cycle or increasing the frequency of the reverse pulse current to alleviate the concentration polarization phenomenon occurring at the interface between the electrode and the electrolyte.

[0130] In the disclosed embodiments, a multi-pulse power supply acts on a liquid flow battery system having a metal deposition type on the negative electrode side. When the metal deposition type liquid flow battery is charged, different pulse electric energies and combinations thereof are set based on the charging parameters of the multi-pulse power supply to control the process of metal electrodeposition on the negative electrode plate. When the metal deposition type liquid flow battery is discharged, different pulse electric energies and combinations thereof are set based on the discharge parameters of the multi-pulse power supply to control the process of metal electrolysis on the negative electrode plate, wherein the pulse electric energies include pulse current, pulse voltage and pulse power.

[0131] In the disclosed embodiments, based on the electrodeposition process of the metal on the negative electrode side during the charging process, pulse power supply charging parameters are selected to charge the liquid flow battery stack to obtain a delicate, uniform and smooth metal deposition layer, wherein the pulse power supply charging parameters are the pulse power supply charging and discharging parameters and the double pulse parameters of the single pulse power supply; based on the electrolysis process of the metal on the negative electrode side during the discharging process, the average pulse power, peak pulse power density and the duty cycle of the positive and reverse pulses during the discharge of the liquid flow battery are adjusted so that the metal deposition layer is ablated layer by layer during the electrolysis process; based on the average pulse power, peak pulse power density and the duty cycle of the positive and reverse pulses during the charging and discharging process, the piezoelectric element arranged in the liquid flow battery unit generates a corresponding ultrasonic field which is mutually coupled with the electric field of the bipolar plate and the electrode plate, so that the morphology of the metal deposition layer on the cathode side remains smooth and dense.

[0132] In the disclosed embodiment, compared with the DC current output by the DC power supply, the pulse current output by the pulse power supply is an on-off DC impulse current, the most typical of which is a square wave pulse current. In addition to the current and voltage, there are also pulse on time and pulse off time for adjustment. The pulse on time and off time can also lead to two important parameters of pulse electrodeposition, namely, pulse frequency and pulse duty cycle. During pulse electrodeposition, there is a certain relationship between the average current density of the electrolyte tank, the peak current density and the pulse duty cycle: when the average current density is constant, the peak current density will vary according to the pulse duty cycle. During the pulse conduction period, the pulse peak current is equivalent to several times or even more than ten times the ordinary DC current. The high overpotential caused by the high current density greatly increases the total number of atoms adsorbed on the cathode surface, making the formation rate of the crystal nucleus much higher than the growth rate of the initial crystal formation, thereby forming a deposition layer with a finer crystal structure. In addition, the high overpotential can also reduce the proportion of side reactions such as hydrogen evolution during the deposition of metals with more negative potentials, which is beneficial to reduce the hydrogen embrittlement of the deposition layer. Therefore, compared with DC electrodeposition, pulse electrodeposition is a strong and advantageous means to control metal electrodeposition. It uses the time function to change the pulse parameters to improve the physical and chemical properties of the deposited layer, thereby obtaining functional (nano-enhanced) metal-based (composite) materials. For example, the metal deposited layer obtained by periodic commutation pulse plating is more delicate and uniform, and has a higher hardness than that obtained by DC plating and DC interruption plating; under reverse high current density, the protruding grains on the surface of the deposited layer are dissolved, and there are few nodular deposits generated in the deposited layer. When the average current density is equal to the DC current density, the current efficiency of pulse plating is higher than that of DC plating. By increasing the duty cycle to increase the peak current density level, the hardness of the metal deposited layer can be increased and the porosity can be reduced. The prepared metal deposited layer has the advantages of low stress, less porosity, low hydrogen content, and high flatness. In addition, the pulse current overcomes the influence of the DC current on the concentration polarization difference of the plating solution, increases the metal deposition rate, refines the grains, and improves the quality of the deposited layer.

[0133] In the disclosed embodiments, for the negative electrode side of the zinc-based liquid flow battery, during the battery charging process, the zinc ions in the electrolyte on the negative electrode side will be deposited on the negative electrode (plate), thereby generating a thicker zinc metal deposition layer. Generally speaking, the zinc metal deposition layer formed by conventional DC charging has coarse particles, obvious pores, an uneven deposition layer surface, and is easy to generate dendritic structures (dendrites). Excessive accumulation of zinc metal deposition layers will cause the ion exchange membrane in the zinc-based liquid flow battery stack to be punctured and fail. At the end of battery charging, due to the high overpotential, hydrogen evolution is likely to occur on the negative electrode. As a side reaction, hydrogen evolution affects the morphology of the zinc metal deposition layer, and is likely to generate coarse metal particles. In addition, in the above stage, the current efficiency of the battery is on a downward trend. By using pulse electrodeposition to adjust the average current density, peak current density and duty cycle during the charging process of the flow battery, the morphology of the zinc metal deposition layer on the negative electrode of the zinc-based flow battery can be improved throughout the charging process, thereby growing a more dense and uniform zinc metal deposition layer with finer grains, reducing the probability of "dead zinc". In addition, when a combination of forward and reverse pulses is used, the flatness of the zinc metal deposition layer will also be improved due to the regular dissolution of the protruding grains on the surface of the deposition layer by the reverse pulse. The combination of multi-pulse electrodeposition technology and the high current density working conditions of the flow battery can effectively improve the long-term energy storage capacity of the flow battery system, and convert the input power fluctuations from the new energy field through the multi-pulse power supply equipment and store them in the flow battery system, thereby effectively smoothing the influence and impact of power fluctuations on the internal structure of the battery stack during the charging process of the flow battery. The discharge process of the zinc-based flow battery can be considered as the reverse process of its charging process. During the discharge process, the average current density, peak current density and duty cycle of the flow battery are adjusted by pulse discharge to gradually dissolve the zinc metal deposit layer. Regular positive pulses are used to replace the local pits caused by the dissolution of the zinc metal deposit layer, and to ensure that the zinc metal deposit layer maintains its flatness and density during the discharge process. This also helps to reduce the probability of producing "dead zinc" in the process.

[0134] In the disclosed embodiments, it can be seen from the above description that during the charging process of the zinc-based liquid flow battery system, there is an optimal multi-pulse parameter set that affects the morphology of the zinc metal deposition layer at the negative electrode, which includes multi-pulse frequency, on / off ratio, average current density, etc., thereby resulting in an optimal zinc metal deposition layer density, grain size, surface roughness, hardness, etc., which are used to characterize the zinc metal deposition layer. Parameter set. The microscopic morphology of the zinc metal deposition layer can be further observed by dissecting the negative electrode of the flow battery stack during charging, and by advanced characterization methods such as scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR); or by measuring the electrochemical impedance spectrum of the interface between the negative electrode and the electrolyte of the flow battery stack by the electrochemical impedance spectroscopy (EIS) method to obtain relevant electrical parameters and parameters for further research (by using microscopic analysis methods, the composition and structure of battery materials can be provided from different angles, which can be used to characterize certain aspects of battery performance. After roughly understanding the battery performance and giving a comprehensive evaluation, an in-depth analysis is conducted on a certain segment. Strictly speaking, these analysis methods belong to combined analysis techniques. This type of analysis method includes: spectroscopy-electrochemistry combined technology, mass spectrometry-electrochemistry combined technology, chromatography-mass spectrometry-electrochemistry combined technology, chromatography-spectroscopy-electrochemistry combined technology, electrochemistry-quartz crystal microbalance combined technology, electrochemistry-scanning probe technology, electrochemistry-surface plasmon resonance detection technology, etc.). The optimal zinc metal deposition layer morphology is conducive to the zinc-based liquid flow battery system to maintain a relatively controllable state during the charging and discharging process, and the irreversible level of the positive and negative sides of the battery stack can be maintained within a certain range for a long time. This is of great significance for controlling the impact of zinc dendrites on the negative electrode side on the ion exchange membrane, improving the life cycle of zinc-based liquid flow batteries, and extending the time span of periodic maintenance of zinc-based liquid flow batteries.

[0135] In the disclosed embodiment, from the perspective of the process of rationally and effectively optimizing the pulse current, the (intelligent) multi-pulse charge and discharge technology can be further combined with the ultrasonic technology, and the ultrasonic wave is applied to the central plate of the flow battery stack, thereby affecting the zinc metal deposition process of the negative electrode of the zinc-based flow battery, and a zinc metal deposition layer with a tighter structure can be prepared, thereby effectively utilizing the space of the negative electrode side reaction chamber in the flow battery stack, and effectively avoiding the battery failure caused by the zinc dendrite deposition morphology piercing the ion exchange membrane in the flow battery stack. The effective use of the (intelligent) multi-pulse power supply in the zinc-based flow battery charging process is reflected in the combination of pulse electrodeposition technology and pulse charging technology; the effective use of the (intelligent) multi-pulse power supply in the zinc-based flow battery discharge process is reflected in the combination of pulse electrolysis technology and pulse discharge technology. Through the use of the pulse power supply, the morphology of the zinc metal deposition layer can be effectively controlled in real time during the zinc-based flow battery charging and discharging process, and at the same time, the charging and discharging efficiency of this type of flow battery can be improved, and the polarization phenomenon and the frequency of side reactions in the battery can be reduced.

[0136] In the disclosed embodiment, the liquid flow battery optimization device is also provided with a liquid flow battery management system, including a power supply and a control system of the liquid flow battery and an ultrasonic power supply and a control system. When the liquid flow battery is a metal deposition type liquid flow battery, the liquid flow battery management system includes the power supply and a control system of the metal deposition type liquid flow battery and an ultrasonic power supply and a control system; the power supply and the control system of the metal deposition type liquid flow battery are used to control the charging and discharging process of the metal deposition type liquid flow battery; the power supply and the control system of the liquid flow battery are used to control the charging and discharging parameters of the multi-pulse power supply and the charging and discharging parameters of the liquid flow battery, and adjust and optimize the real-time charging and discharging efficiency of the liquid flow battery stack based on the charging and discharging parameters and the discharging parameters.

[0137] In the embodiments of the present disclosure, the power supply of the metal deposition type liquid flow battery and its control system are used to control the charging and discharging parameters of the multi-pulse power supply and the charging and discharging parameters of the liquid flow battery, adjust and optimize the morphology of the metal deposition layer on the negative electrode side and the real-time charging efficiency of the liquid flow battery stack based on the charging parameters of the liquid flow battery, and adjust and optimize the morphology of the electrolysis of the metal deposition layer on the negative electrode side and the real-time discharge efficiency of the liquid flow battery stack based on the discharge parameters of the liquid flow battery; the ultrasonic power supply control system is used to control the alternating voltage output by the ultrasonic driving power supply, and control the frequency, amplitude and phase of the corresponding ultrasonic vibration generated by the piezoelectric element based on the alternating voltage, which is used for preparing a dense, uniform and more refined cathode side metal deposition layer for the metal deposition type liquid flow battery, and can drive the ultrasonic field to couple with the multi-pulse electric field to improve the charging and discharging efficiency of the liquid flow battery.

[0138] In the disclosed embodiment, in order to ensure that the liquid flow battery system can work efficiently, stably and for a long time at high power during the deployment of commercial projects, it is necessary to solve the problems existing in the material and structural design of important components such as electrodes, flow channels, and diaphragms in the liquid flow battery stack. Focusing on the coupling problem of thermal flow science and (electro)chemical engineering in liquid flow batteries, it is necessary to solve the problem of improving the electrode transmission performance and electrochemical performance at the same time, the problem of uniform distribution of high active materials and low flow resistance in the flow channel, and the problem of high ion conductivity and high selective permeability of the diaphragm. For zinc-based liquid flow batteries, the zinc metal deposition layer that appears on the negative electrode side electrode of the battery during the charging and discharging process will hinder the further improvement of the electrode transmission capacity and electrochemical performance in the process; it will cause the electrolyte flow channel in the negative electrode side chamber of the battery to be in a changing process all the time, which is not conducive to the charging and discharging process of zinc-based liquid flow batteries, and is not conducive to the reasonable use of zinc-based liquid flow batteries for energy storage and energy conversion. It is very meaningful to use multi-pulse electrodeposition and electrolysis technology reasonably to ensure the density and fine grain size of the zinc metal deposition layer at the negative electrode side electrode during the charging and discharging process of zinc-based liquid flow batteries. In addition, by using pulse charge and discharge technology, the average current density, peak current density, duty cycle (on / off ratio), and multi-pulse frequency parameters can be reasonably adjusted to further improve the concentration polarization phenomenon that may occur at the interface between the electrode and the electrolyte, which has a certain mitigating effect on the mass transfer obstruction phenomenon that is easy to occur in zinc-based liquid flow batteries at high power. During the charging process, the mass transfer diffusion polarization of the liquid flow battery often occurs at the end of the reaction. In addition to increasing the electrolyte flow rate at this stage (under high SOC), it can be considered to maintain the average current density. Under the premise of increasing the peak current density by changing the duty cycle or increasing the frequency of the reverse pulse current, the concentration polarization phenomenon occurring at the interface between the electrode and the electrolyte can be alleviated. During the discharge process, the initial discharge voltage value of the liquid flow battery decreases sharply with the increase of the discharge current density, resulting in a decrease in voltage efficiency due to increased polarization loss. Continuously using pulsed current to generate electricity during the discharge process helps to obtain a flatter discharge curve, prolong the discharge time, and increase the discharge capacity. The selection and optimization of parameters related to the use of multi-pulse current density in the charging and discharging process of zinc-based liquid flow batteries can be obtained through relevant experiments.

[0139] In the disclosed embodiment, during the charge and discharge process of the flow battery, the integrated structure of the bipolar plate and the electrode in the flow battery stack can make comprehensive use of electrical energy and mechanical energy (ultrasonic vibration energy). A multi-pulse current for charge and discharge of the flow battery is provided by a (smart) multi-pulse power supply to alleviate various polarization phenomena occurring at the interface between the electrode and the electrolyte; ultrasonic drive power supply, ultrasonic transducer and piezoelectric ceramic (crystal) are provided to generate ultrasonic vibration energy to alleviate various polarization phenomena occurring at the interface between the electrode and the electrolyte, and to make the zinc metal deposition layer more compact, thereby delaying the time for the dendrite morphology of the zinc metal deposition layer to pierce the ion exchange membrane in the flow battery stack.

[0140] In the embodiments of the present disclosure, for most chronoamperometric experiments, the time scale is 0.001 to 10 s, and the thickness of the diffusion layer at the interface between the electrode and the electrolyte is between a few microns and several hundred microns, which is much greater than the roughness of a well-polished electrode (generally less than a few tenths of a micron). Fig.13 FIG. 4 is a schematic diagram showing the effect of the rough electrode surface on the diffusion layer in the time dimension according to an embodiment of the present disclosure. Fig.13 As shown in the figure, for the diffusion layer, the electrode can be considered to be flat, the isoconcentration lines of the diffusion layer are parallel to the electrode surface, and the cross section of the diffusion field is equal to the geometric area of ​​the electrode. However, when the roughness size of the electrode is larger than the thickness of the diffusion layer, the area of ​​the diffusion isoconcentration surface depends on the characteristics of the electrode surface, which is larger than the geometric area of ​​the electrode and close to the microscopic area (of course, this area is still smaller than the microscopic area, because in the diffusion field, the roughness smaller than the thickness of the diffusion layer is averaged). It is assumed that the roughness of the electrode surface originates from the ideal sawtooth shape. The dotted line in the figure represents the isoconcentration surface in the diffusion layer, and the vector indicated by the arrow represents the concentration gradient of the electrolyte on the electrode surface. Fig.13 (a) is the long-term distribution of the diffusion layer on the rough electrode interface. Fig.13 (b) is the distribution of the diffusion layer on the rough electrode interface for a short time. For electrodes with large areas but only partial areas being active, similar analysis is required to understand their chronoamperometric behavior. Array electrodes prepared by welding technology, with conductive blocks welded between the bipolar plates and the electrode plates for electrical connection, and insulating gaskets inserted inside (similar to array electrodes prepared by microelectronics technology, or composite electrodes formed by dispersing conductive particles such as graphite in insulating materials such as polymers).

[0141] In the disclosed embodiment, the conductive pillar is electrically connected to the conductive phase and the inert electrode surface. Fig.14 FIG. 1 shows a schematic diagram of the active area and inert area of ​​the electrode surface and their influence on the diffusion layer in an embodiment of the present disclosure, such as Fig.14(a) to (c) show how the distribution of the diffusion layer between the inert electrode surface and the electrolyte (due to the insertion of an insulating substrate between the conductive columns, the interface diffusion layer is only affected by the electric field) changes over time and tends to be uniform.

[0142] In the embodiment of the present disclosure, within a short time range, when the thickness of the diffusion layer is smaller than the size of the electrode active point, each active point generates its own diffusion field, such as Fig.14 As shown in (a), the total diffusion field area is the sum of the active areas. As time goes by, each independent diffusion field will extend outward from the active point interface, and linear diffusion will gradually evolve into micro-radial diffusion, such as Fig.14 As shown in (b). As time goes by, when the thickness of the diffusion layer reaches the distance between adjacent active points, the separated diffusion fields begin to merge into one field and show the characteristics of linear diffusion again. The electrode area is the total geometric area of ​​the entire electrode including the insulating area, as shown in Fig.14 (c) As shown. At this time, it is impossible to distinguish each independent active area, and the electrode exhibits uniform behavior. At this time, the distance difference and time difference of molecules (ions) from far away in the solution (compared with the spacing of the active areas) to diffuse to different active sites can be ignored. For regular array electrodes or the more uniform and dense the distribution of active point sizes, the above electrodes can reach a uniform state in a shorter time, and the distribution of the above electrodes and the electrolyte diffusion layer can reach a uniform state in a shorter time (in engineering design, there is a compromise between the area of ​​independent active areas and the distribution density of conductive blocks). Fig.14 (d) shows that a piezoelectric element is inserted between the conductive blocks. The interface diffusion layer is affected by the electric field and the ultrasonic field. The homogenization process of the diffusion layer is faster, and the active material on the surface of the inert electrode is more evenly distributed, which reduces the possibility of concentration polarization. For liquid flow batteries, the introduction of ultrasonic fields on the surface of the inert electrode during the charge and discharge process helps to alleviate various polarization phenomena that occur at the interface between the electrode and the electrolyte. For zinc-based liquid flow batteries, it can make the zinc metal deposition layer denser, thereby delaying the time when the dendrite morphology of the zinc metal deposition layer pierces the ion exchange membrane in the liquid flow battery stack.

[0143] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0144] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present disclosure, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0145] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A flow battery optimization device, characterized in that: The device comprises: A liquid flow battery stack and an embedded ultrasonic sound generating device, wherein the liquid flow battery stack is composed of liquid flow battery cells electrically connected in series; The liquid flow battery unit comprises: an integrated assembly of a bipolar plate and an electrode plate, an ion exchange membrane, and an electrode frame, wherein the integrated assembly of the electrode plate comprises a negative electrode plate and / or a positive electrode plate, and conductive columns uniformly arranged between the bipolar plate and the negative electrode plate and the positive electrode plate, and the bipolar plate and the negative electrode plate and the positive electrode plate are electrically connected based on the uniformly distributed conductive columns to realize the electrical series connection of the liquid flow battery unit; The ultrasonic sound generating device comprises: an ultrasonic driving power supply and a piezoelectric element; The piezoelectric element is arranged between the bipolar plate and the positive plate and / or the negative plate. The ultrasonic driving power supply supplies power to the piezoelectric element to make the piezoelectric element perform ultrasonic vibration. The ultrasonic vibration acts on the bipolar plate, the negative plate and / or the positive plate respectively. The relevant parameters of the ultrasonic vibration include the frequency, amplitude and phase of the vibration.

2. The device according to claim 1, characterized in that The piezoelectric element is uniformly filled between the positive electrode plate and / or the negative electrode plate and the bipolar plate; A resin material resistant to electrolyte corrosion is filled between the bipolar plate and the electrode plate to prevent the conductive column and the piezoelectric element from contacting the electrolyte, and the resin material is also used to fix the relative position between the piezoelectric element and the conductive column; The piezoelectric element is a piezoelectric crystal or a piezoelectric film; The piezoelectric crystal or the piezoelectric film is arranged on the periphery of the conductive column.

3. The device according to claim 2, characterized in that The ultrasonic driving power supply is connected to the positive electrode and the negative electrode of the piezoelectric crystal or the piezoelectric film based on a wire, and the frequency, amplitude and phase of the corresponding ultrasonic vibration generated by the piezoelectric crystal or the piezoelectric film are controlled by setting the alternating voltage output by the ultrasonic driving power supply; During the charge and discharge process of the liquid flow battery, the electric field generated by the integrated assembly of the bipolar plate and the electrode plate acts together on the positive plate and / or the negative plate, and the conductive columns evenly distributed on the positive plate and / or the negative plate make the active substances in the diffusion layer of the contact interface between the corresponding electrode and the electrolyte evenly distributed. The ultrasonic field generated by the ultrasonic vibration of the evenly distributed piezoelectric crystals or the piezoelectric film further acts on the contact interface between the electrode and the electrolyte, so that the active substances in the diffusion layer are further evenly distributed.

4. The device according to claim 3, characterized in that The piezoelectric crystal is provided with a positive electrode and a negative electrode, the positive electrode of at least one of the piezoelectric crystals is connected together, and the negative electrode is connected together, so that the upper and lower surfaces are arranged in a consistent manner to form a shared positive electrode and a shared negative electrode structure, and the shared positive electrode and the shared negative electrode structure in at least one of the liquid flow battery units are connected in series or in parallel and connected to the ultrasonic drive power supply through a lead wire; The positive electrode and the negative electrode of the piezoelectric film are arranged on both sides of the film, and at least one of the piezoelectric films is stacked so that the positive electrode and the negative electrode are connected in series or in parallel to form a piezoelectric film integrated structure, and the piezoelectric film integrated structure in at least one liquid flow battery unit is connected in series or in parallel, and is connected to the ultrasonic drive power supply through the lead wire; The ultrasonic driving power source is connected to the positive electrode and the negative electrode of each liquid flow battery unit which are formed into an integrated structure by the piezoelectric crystal or the piezoelectric film based on a distributed wire link; The ultrasonic driving power source controls the magnitude of the alternating voltage transmitted to the integrated structure composed of the piezoelectric crystal or the piezoelectric film in each flow battery unit based on the distributed wire link; Based on the frequency, amplitude and phase of the ultrasonic vibration, the ultrasonic field is generated in the liquid flow battery unit by an integrated structure composed of the piezoelectric crystal or the piezoelectric film, and acts on each of the liquid flow battery units.

5. The device according to claim 2, characterized in that The piezoelectric crystals are evenly distributed between the positive plate and / or the negative plate and the bipolar plate; Or the piezoelectric film is evenly distributed between the positive electrode plate and / or the negative electrode plate and the bipolar plate; The conductive posts are symmetrically or asymmetrically distributed with the bipolar plate as the center, and the piezoelectric elements are arranged based on the corresponding arrangement of the conductive posts. When the piezoelectric elements are evenly distributed between the positive plate and the negative plate, they are symmetrically or asymmetrically distributed with the bipolar plate as the center, so as to improve the uniformity and consistency of the interface between the electrode plate and the electrolyte in the liquid flow battery unit; The external power supply system applies an electric field to each of the flow battery cells in the flow battery stack through the positive and negative current collectors at both ends of the flow battery stack, and couples with the ultrasonic field generated by the piezoelectric element provided in the flow battery cell, and acts together on the interface between each electrode of the flow battery cell and the electrolyte; Or the position of the piezoelectric element is set according to the coupling relationship between the ultrasonic field when the piezoelectric element is working and the electric field generated when the flow battery stack is working.

6. The device according to claim 2, characterized in that The material of the piezoelectric film includes at least one of the following: polyvinylidene fluoride, polyvinylidene fluoride copolymer, polymer of 3,4-ethylenedioxythiophene monomer, sodium polystyrene sulfonate, aluminum nitride, carbon base; The material of the piezoelectric crystal includes at least one of the following: lead-zinc-titanium compound, lead zirconate titanate, barium titanate, barium strontium titanate, lead lanthanum zirconate titanate, and lithium sulfate; The preparation method of the piezoelectric film includes one of the following: sol-gel method, vacuum evaporation method, sputtering method, chemical vapor deposition method, pulsed laser deposition, electrochemical plating; wherein the sputtering method includes radio frequency magnetron sputtering method and direct current magnetron sputtering method; The piezoelectric crystal is manufactured by sintering.

7. The device according to claim 1, characterized in that The bipolar plate is configured as a closed two-dimensional space structure; The closed two-dimensional spatial structure plane of the bipolar plate is parallel to the plane where the ion exchange membrane is located, and the material of the bipolar plate is selected from metal-based, carbon-based, or a metal-based and carbon-based composite based on the materials of the positive electrode and the negative electrode; A wire required for connecting an ultrasonic driving power source is arranged in a hollow structure in the closed two-dimensional space structure of the bipolar plate, and the outside of the two-dimensional space structure is a closed plate for isolating the electrolyte.

8. The device according to claim 1, characterized in that The flow battery stack adopts a multi-pulse power supply for charging and discharging; The multi-pulse power source acts on the positive and negative electrodes of each flow battery unit through the positive and negative current collectors at both ends of the flow battery stack and the internal structure of the flow battery stack, so as to affect the positive and negative electrodes and their electrolyte interfaces; The multi-pulse power supply includes: a single-pulse power supply and a double-pulse power supply, which are combined or work separately based on the actual charge and discharge conditions of the flow battery stack, and act on the positive and negative current collectors of the flow battery stack; Setting single pulse parameters based on the single pulse power supply, including: pulse frequency, pulse duty cycle and pulse peak power, wherein the pulse frequency is calculated based on the pulse on-off cycle; Calculating the pulse peak electric energy based on the pulse duty cycle and the pulse average electric energy, and setting the pulse power supply charging and discharging parameters of the single pulse power supply based on the pulse frequency, the pulse duty cycle and the pulse peak electric energy; Based on the dual-pulse power supply, dual-pulse parameters are set, including: forward and reverse pulse frequencies, forward and reverse pulse duty ratios, and forward and reverse pulse peak electrical energies, wherein the forward and reverse pulse frequencies are calculated based on the forward pulse on-off cycle and the reverse pulse on-off cycle; Calculate the forward and reverse pulse peak energy based on the percentage of the forward pulse time and the reverse pulse time in the pulse working period, the average energy of the forward pulse time, the average energy of the reverse pulse and the forward and reverse pulse duty cycle; Setting the pulse power supply charge and discharge parameters of the dual pulse power supply based on the positive and reverse pulse frequencies, the positive and reverse pulse duty ratios and the positive and reverse pulse peak electrical energies; Wherein, the electrical energy input or output includes: pulse current, pulse voltage and pulse power; When the multi-pulse power supply is used to charge the liquid flow battery system, different pulse electric energies and combinations thereof are set based on the pulse power supply charging parameters, so that the charging efficiency of the liquid flow battery system is improved; Based on the average pulse electric energy, the peak pulse electric energy density and the positive and reverse pulse duty ratios during the discharge process, the discharge efficiency of the liquid flow battery system is controlled and improved.

9. The device according to claim 8, characterized in that The multi-pulse power source acts on a liquid flow battery system of a metal deposition type on the negative electrode side; When the flow battery is charged, different pulse electric energies and combinations thereof are set based on the charging parameters of the multi-pulse power supply to control the process of metal electrodeposition on the negative electrode plate, wherein the pulse electric energy includes pulse current, pulse voltage and pulse power; When the liquid flow battery is discharged, different pulse electric energies and combinations thereof are set based on the discharge parameters of the multi-pulse power supply to control the electrolysis process of the metal on the negative plate, wherein the pulse electric energy includes pulse current, pulse voltage and pulse power; Based on the electrodeposition process of the metal on the negative electrode side during the charging process, a pulse power supply charging parameter is selected, and the flow battery stack is charged based on the pulse power supply charging parameter to obtain a fine, uniform and smooth metal deposition layer; Based on the electrolysis process of the metal on the negative electrode side during the discharge process, the average pulse power, the peak pulse power density and the positive and reverse pulse duty ratios during the discharge of the flow battery are adjusted so that the metal deposition layer is ablated layer by layer during the electrolysis process; Based on the average pulse electric energy, the peak pulse electric energy density and the positive and reverse pulse duty ratios during the charge and discharge process, the piezoelectric element arranged in the liquid flow battery unit generates the corresponding ultrasonic field, which is coupled with the electric field of the bipolar plate and the electrode plate, so that the morphology of the metal deposition layer on the cathode side remains flat and dense.

10. The device according to claim 9, characterized in that The device also includes a flow battery management system; The liquid flow battery management system includes a power supply and a control system of the liquid flow battery and an ultrasonic power supply and a control system. When the liquid flow battery is a metal deposition type liquid flow battery, the liquid flow battery management system includes a power supply and a control system of the metal deposition type liquid flow battery and an ultrasonic power supply and a control system. The power supply of the liquid flow battery and its control system are used to control the charge and discharge parameters of the multi-pulse power supply and the charge and discharge parameters of the liquid flow battery, and adjust and optimize the real-time charge and discharge efficiency of the liquid flow battery stack based on the charge and discharge parameters and the discharge parameters; The power supply of the metal deposition type liquid flow battery and the control system thereof are used to control the charging and discharging process of the metal deposition type liquid flow battery; The power supply of the metal deposition type liquid flow battery and its control system are used to control the charge and discharge parameters of the multi-pulse power supply and the charge and discharge parameters of the liquid flow battery, adjust and optimize the morphology of the metal deposition layer on the negative electrode side and the real-time charging efficiency of the liquid flow battery stack based on the charging parameters of the liquid flow battery, and adjust and optimize the morphology of the electrolysis of the metal deposition layer on the negative electrode side and the real-time discharge efficiency of the liquid flow battery stack based on the discharge parameters of the liquid flow battery; The ultrasonic power supply control system is used to control the alternating voltage output by the ultrasonic driving power supply, and based on the alternating voltage, controls the frequency, amplitude and phase of the corresponding ultrasonic vibration generated by the piezoelectric element, which is used to prepare a dense, uniform and more refined cathode side metal deposition layer for the metal deposition type liquid flow battery, and can drive the ultrasonic field to couple with the multi-pulse electric field, thereby improving the charging and discharging efficiency of the liquid flow battery.

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