Method for localised ultrasound assisted enhancement of chemical reactions in flow batteries

Abstract

This invention provides a method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance, comprising the following steps: (1) setting an ultrasonic transducer on the bipolar plates of the positive and negative half-cells of the flow battery. The position and size of the ultrasonic transducer on the bipolar plates should ensure that the area of ​​action of the ultrasound applied by the ultrasonic transducer covers the flow dead zone inside the porous electrode; (2) connecting a signal generator to the ultrasonic transducer via a power amplifier; (3) during the operation of the flow battery, turning on the signal generator and power amplifier to apply ultrasound to the flow battery through the ultrasonic transducer, thereby improving the flow rate and flow uniformity of the electrolyte in the porous electrode and enhancing the chemical reaction of the flow battery. The method of this invention can effectively improve the flow uniformity of the electrolyte inside the porous electrode, realize flexible control of the flow field inside the porous electrode of the flow battery, and reduce the ultrasonic power consumption for flow field control inside the electrode.

Description

Technical Field

[0001] This invention belongs to the field of long-term energy storage technology and relates to a method for enhancing the chemical reaction of flow batteries based on local ultrasound-assisted enhancement. Background Technology

[0002] Flow batteries, a novel electrochemical energy storage technology, achieve the interconversion of electrical and chemical energy through reversible redox reactions of active materials in the positive and negative electrolytes. Due to their high commercial value, short response time, decoupling of power and capacity, long lifespan, high safety, and low pollution, flow batteries are gradually becoming the preferred strategy for large-scale energy storage. During the charge-discharge cycle of a flow battery, the uniformity of electrolyte flow directly affects its energy efficiency. However, current flow batteries suffer from poor flow field uniformity, severely hindering their commercial development and application.

[0003] In existing technologies, the main methods for improving the uniformity of the internal flow field in flow batteries are the design of bipolar channels and the optimization of the battery system flow rate. By designing flow channels on the surface of the bipolar plates in a flow battery, the flow state of the electrolyte within the electrodes can be altered, allowing the electrolyte to permeate into the porous electrodes, thereby improving mass transfer on the surface of the porous electrodes, reducing flow losses, and enhancing battery performance. Optimizing the flow rate can balance the capacity decay and voltage loss of the flow battery, further improving battery performance. However, even after designing flow channels and optimizing the flow rate on the bipolar plates, dead zones still exist at the corners of the porous electrodes in the flow battery. Furthermore, the design of bipolar channel flow patterns is expensive, and once fabricated, it is impossible to flexibly control the flow field under different operating conditions.

[0004] In contrast, ultrasound is an excellent energy field-assisted method that enables non-contact manipulation of fluids and allows for real-time adjustments at different battery operating stages. Furthermore, the device is simple, reliable, and flexibly arranged, and can be placed separately for flow dead zones in flow batteries. This has led to the widespread application of ultrasound in electrochemistry and its increasing use in battery technology. Currently, low-frequency ultrasound can improve the conductivity and reduce the viscosity of electrolytes in deep eutectic solvent (DES) flow batteries, thereby reducing internal losses in redox batteries and ultimately increasing the redox reaction rate (see Sun P., Lu P., Xu J., et al. Electrochimica Acta, 2021, 394:139-140.). Ultrasonic transducers can be used to pump electrolyte and improve the flow uniformity of electrolyte, thereby promoting the discharge performance of the battery (see Huang H., Liu P., Ma Q., et al. Enabling a high-performance saltwater Al-air battery via ultrasonicallydriven electrolyte flow[J]. Ultrasonics Sonochemistry, 2022, 88:106-104.). However, existing ultrasonic-assisted strategies have the following shortcomings: (1) When applying ultrasound, thermal effects are often coupled, and the influence of acoustic flow effect on battery performance has not been studied separately; (2) Continuous application of ultrasound throughout the battery cycle leads to excessive energy consumption, which is not conducive to reducing the energy consumption of the battery system; (3) The ultrasound is applied to the entire battery without improving the flow state in local areas. Although applying ultrasound to the entire battery can improve the overall performance of the electrolyte, it cannot effectively improve the flow uniformity of the electrolyte in the flow dead zone inside the porous electrode.

[0005] In summary, existing methods for improving battery performance using ultrasound assistance cannot achieve efficient control of the flow field inside porous electrodes. Furthermore, the high energy consumption of ultrasound devices reduces the net power of the battery system and increases the cost of controlling the flow field inside the electrodes, hindering their large-scale application in long-term energy storage technology. Summary of the Invention

[0006] To address the issues that existing methods for improving battery performance using ultrasound-assisted methods cannot effectively improve the flow uniformity of the flow dead zone inside porous electrodes, and that high ultrasonic power consumption reduces the net power of the battery system and increases the cost of controlling the internal flow field, this invention provides a method for enhancing the chemical reaction of a flow battery using localized ultrasound assistance. This method effectively improves the flow uniformity of the electrolyte inside the porous electrode, enables flexible control of the internal flow field of the flow battery, and reduces the ultrasonic power consumption for controlling the internal flow field of the electrode.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance, comprising the following steps:

[0009] (1) Mounting holes are provided on the current collectors and end plates of the positive and negative half-cells of the flow battery. The mounting holes are matched with ultrasonic transducers. Ultrasonic transducers are provided on the bipolar plates of the positive and negative half-cells of the flow battery. The ultrasonic transducers are placed against the side of the bipolar plates close to the current collector. The surface of the ultrasonic transducer in contact with the bipolar plates has a planar structure. The position of the ultrasonic transducer on the bipolar plates and the size of the ultrasonic transducer should ensure that the area of ​​action of the ultrasonic waves applied by the ultrasonic transducer covers the flow dead zone inside the porous electrode.

[0010] The acoustic impedance of the bipolar plate is matched with the ultrasound applied by the ultrasonic transducer, and the thickness of the bipolar plate is matched with the half wavelength of the ultrasound applied by the ultrasonic transducer; (2) Connect the output of the signal generator to the input of the power amplifier, and connect the output of the power amplifier to the input of the ultrasonic transducer.

[0011] (3) Turn on the electrolyte pump of the flow battery to pump electrolyte to the positive half cell and the negative half cell to run the flow battery. During the operation of the flow battery, turn on the signal generator and power amplifier to apply ultrasound to the flow battery through the ultrasonic transducer. Use ultrasound to improve the flow rate and flow uniformity of the electrolyte in the porous electrode and enhance the chemical reaction of the flow battery.

[0012] In step (3) of the above technical solution, in order to alleviate the problem of excessively high temperature of the flow battery caused by the application of ultrasound, the temperature of the positive and negative electrolytes is regulated by a temperature control device during the operation of the flow battery, mainly by lowering the temperature of the positive and negative electrolytes. Further, during the operation of the flow battery, it is preferable to regulate the temperature of the positive and negative electrolytes between 0 and 50°C using a temperature control device. More preferably, during the operation of the flow battery, the temperature of the positive and negative electrolytes is regulated between 0 and 35°C using a temperature control device.

[0013] In the above technical solution, in order to achieve flexible control of the positive half-cell and the negative half-cell in practical applications and avoid increasing unnecessary energy consumption, the ultrasonic transducers set on the bipolar plates of the positive half-cell and the negative half-cell should preferably work independently.

[0014] Furthermore, in the above technical solution, in order to specifically regulate and enhance the flow field in a local area (e.g., a flow dead zone) of a certain half-cell in practical applications, at least one ultrasonic transducer should be provided on the bipolar plate of the positive half-cell, preferably at least two ultrasonic transducers should be provided on the bipolar plate of the positive half-cell. When the number of ultrasonic transducers provided on the bipolar plate of the positive half-cell is ≥2, each ultrasonic transducer operates independently. Similarly, at least one ultrasonic transducer should be provided on the bipolar plate of the negative half-cell, preferably at least two ultrasonic transducers should be provided on the bipolar plate of the negative half-cell. When the number of ultrasonic transducers provided on the bipolar plate of the negative half-cell is ≥2, each ultrasonic transducer operates independently.

[0015] In the above technical solution, the ultrasonic transducer includes at least one of a piezoelectric ultrasonic transducer and an electromagnetic acoustic transducer. Further, the piezoelectric ultrasonic transducer includes a piezoelectric ceramic sheet, a sandwich ultrasonic transducer, or an interdigital transducer.

[0016] In the above technical solution, to ensure that the ultrasound emitted by the ultrasonic transducer effectively enhances the chemical reaction of the flow battery, the placement and size of the ultrasonic transducer on the bipolar plate should ensure that the area of ​​action of the ultrasound applied by the ultrasonic transducer covers the flow dead zone inside the porous electrode. The flow dead zone refers to the area where the flow velocity of the electrolyte within the electrode does not exceed 1.15 mm / s.

[0017] Furthermore, in the above technical solution, the placement position of the ultrasonic transducer on the bipolar plate and the size of the ultrasonic transducer preferably meet the following requirements: the ultrasonic transducer is placed on the bipolar plate corresponding to the flow dead zone of the porous electrode, and the total area of ​​the contact surface between all ultrasonic transducers placed on the same bipolar plate and the bipolar plate is denoted as A1, the area of ​​the surface in contact with the porous electrode and the bipolar plate is denoted as A0, and the area of ​​the flow dead zone inside the porous electrode in contact with the bipolar plate is denoted as A2, A1:A0=(A2 / A0~1.2):1.

[0018] In the above technical solution, during the operation of the flow battery, the vibration frequency of the ultrasonic transducer is controlled to be 0.02 to 10 MHz. The vibration frequency of the ultrasonic transducer can be adjusted by adjusting the input voltage of the signal generator.

[0019] In the above technical solution, ultrasound can be applied continuously or intermittently during the operation of the flow battery. In order to reduce the energy consumption of ultrasound, it is preferable to apply ultrasound intermittently during the operation of the flow battery.

[0020] In the above technical solution, the bipolar plate should have good conductivity, and the acoustic impedance of the bipolar plate should match the ultrasound applied by the ultrasonic transducer, and the thickness of the bipolar plate should match the half-wavelength of the ultrasound applied by the ultrasonic transducer. Feasible bipolar plates include metal bipolar plates, graphite bipolar plates, or carbon-plastic composite bipolar plates. Feasible carbon-plastic composite bipolar plates include polypropylene bipolar plates. Here, the polypropylene bipolar plate is made of polypropylene containing conductive fillers. In the art, bipolar plates of this type are commonly referred to as polypropylene bipolar plates.

[0021] In the above technical solution, during the operation of the flow battery, the flow rate of the electrolyte pumped to the positive and negative half-cells is controlled to be 5–200 mL / min. -1 .

[0022] In the above technical solution, during the operation of the flow battery, the current density of the flow battery is controlled to be 50–500 mA / cm². -2 .

[0023] In the above technical solution, the flow battery includes any one of the following: vanadium redox flow battery, iron-chromium flow battery, zinc-bromine flow battery, zinc-iron flow battery, organic flow battery, and hydrogen-bromine flow battery.

[0024] Compared with the prior art, the technical solution of the present invention can produce the following beneficial technical effects:

[0025] 1. This invention provides a method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance. The method involves placing an ultrasonic transducer attached to the bipolar plates of the positive and negative half-cells of the flow battery, near the current collector. The transducer's placement and size on the bipolar plates should ensure that the area of ​​ultrasound applied by the transducer covers the flow dead zone inside the porous electrode. A signal generator is connected to the ultrasonic transducer via a power amplifier. During flow battery operation, the signal generator and power amplifier are activated to apply ultrasound to the flow battery through the ultrasonic transducer. Ultrasound is used to improve the flow rate and uniformity of the electrolyte within the porous electrode, particularly enhancing the flow state of the electrolyte in the flow dead zone of the porous electrode, thereby strengthening the chemical reaction of the flow battery. This invention provides a flow field velocity regulation strategy within the electrodes of a flow battery. The ultrasonic application process is flexible and efficient, allowing for flow field regulation of specific electrode regions (e.g., flow dead zones). The area of ​​ultrasonic application is adjustable, and it can be combined with appropriate ultrasonic application strategies to reduce battery energy consumption (e.g., continuous or intermittent ultrasonic application, with varying time intervals between intermittent applications). This method allows for flow field control of specific flow dead zones, significantly improving ultrasonic efficiency. Combined with suitable ultrasonic application strategies, it reduces battery energy consumption, improves economic efficiency, and is beneficial for commercial applications. It solves the problems of high battery energy consumption resulting from continuous ultrasonic application to the battery in existing technologies, and low ultrasonic efficiency when ultrasonic application is applied to the entire flow battery.

[0026] 2. The method described in this invention can also cool the positive and negative electrolytes using a temperature control device to avoid the problem of excessively high battery temperature caused by the application of ultrasonic coupling heat effect, thereby avoiding adverse effects on the performance of the flow battery due to excessively high battery temperature.

[0027] 3. The method described in this invention is an active control strategy that can be flexibly and specifically adjusted according to different operating conditions of the flow battery. For example, the intensity, location, duration, and application method of ultrasound, as well as the temperature of the electrolyte, can be flexibly adjusted according to the battery's operating conditions to specifically enhance the chemical reaction of the flow battery. Compared with the existing technology that enhances the reaction by designing flow channels on the bipolar plates, the method described in this invention has a wider range of applicable operating conditions for flow batteries, a more flexible control method, and strong scalability, making it very suitable for the commercial application of large-scale flow batteries. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the ultrasonic-assisted vanadium redox flow battery in Example 1. Figure 1 In the diagram, 1—end plate, 2—current collector, 3—ion membrane, 4—bipolar plate, 5—electrode frame, 6—porous electrode, and 7—ultrasonic transducer.

[0029] Figure 2 This is a schematic diagram illustrating the principle of ultrasound acting on a vanadium redox flow battery in Example 1.

[0030] Figure 3 This is a comparison diagram of the flow field distribution on the middle section of the negative electrode in Example 2 with and without ultrasound.

[0031] Figure 4 It is a comparison diagram of electrolyte flow rate distribution in the negative electrode with and without ultrasound, drawn along the diagonal.

[0032] Figure 5 This is a schematic diagram of the experimental apparatus described in Example 3. In the diagram, 8—ultrasound-assisted vanadium redox flow battery, 9—signal generator, 10—power amplifier, 11—charge and discharge tester, 12—temperature control device, 13—digital thermometer, and 14—peristaltic pump.

[0033] Figure 6 This is a photograph of the ultrasonic-assisted vanadium redox flow battery in Example 3 (taken from one end plate).

[0034] Figure 7 This is the temperature change curve of the battery with ultrasonic treatment time when different intensities of ultrasound are applied without temperature control in Example 3.

[0035] Figure 8 This is a graph showing the relationship between the set temperature of the temperature control device and the actual temperature of the battery under ultrasonic and non-ultrasonic conditions when temperature control is implemented in Example 3.

[0036] Figure 9 This describes the effect of battery operating temperature on battery efficiency in Example 4, with and without ultrasound.

[0037] Figure 10 This is a schematic diagram of a model of ultrasound acting on a battery created using COMSOL Multiphysics software in Example 5.

[0038] Figure 11 This is a schematic diagram of the acoustic flow acting within the electrode in Example 5.

[0039] Figure 12 This refers to the sound field distribution and flow field distribution when ultrasound propagates within the electrode in Example 5.

[0040] Figure 13 This refers to Example 5, specifically the V-shaped cross-section inside the negative electrode with and without ultrasound. 2+ Distribution map.

[0041] Figure 14 This refers to Example 5, where V is measured at different cross-sections of the negative electrode with and without ultrasound. 2+ Distribution uniformity factor.

[0042] Figure 15 Example 5 shows the V-shaped cross-section inside the negative electrode under different current density conditions, with and without ultrasound. 2+ Distribution uniformity factor.

[0043] Figure 16 Example 5 shows the V-shaped cross-section inside the negative electrode under different SOC conditions, with and without ultrasound. 2+ Distribution uniformity factor.

[0044] Figure 17 This is a graph showing the relationship between the input voltage of different signal generators and the actual output voltage of the piezoelectric ceramic sheet in Example 6.

[0045] Figure 18 This illustrates the effect of different signal generator input voltages on battery efficiency in Example 6.

[0046] Figure 19 Example 7 illustrates the effect of different current densities on battery efficiency with and without ultrasound.

[0047] Figure 20 This is a photograph of the piezoelectric ceramic sheet mounted on the bipolar plate in the experimental setup of Example 8.

[0048] Figure 21 This is a schematic diagram of different ultrasound application locations in Example 8.

[0049] Figure 22 Example 8 illustrates the effect of applying ultrasound to the battery efficiency without it and applying it at different locations.

[0050] Figure 23 This is a schematic diagram of the ultrasonic application method in Example 9, the temperature changes during battery operation, and the battery power consumption.

[0051] Figure 24 This illustrates the effect of different ultrasonic application methods on battery efficiency in Example 9.

[0052] Figure 25 This is a schematic diagram of the dimensions of the porous electrodes on industrial and laboratory scales in Example 10.

[0053] Figure 26 This is a schematic diagram of an industrial-scale battery model constructed using COMSOL Multiphysics software, as shown in Example 10.

[0054] Figure 27 This is a comparison diagram of the flow field and streamlines on the intermediate cross section of the negative electrode with and without ultrasound in Example 10.

[0055] Figure 28This is a comparison of the average flow rate of the electrolyte in the negative electrode before and after ultrasonication under porous electrode conditions of laboratory scale in Example 2 and industrial scale in Example 10. Detailed Implementation

[0056] The following examples further illustrate the method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance provided by the present invention. It should be noted that the following examples are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0057] Since the principle of enhancing the chemical reaction of all types of flow batteries is the same as that of enhancing the chemical reaction of vanadium redox flow batteries, the following embodiments use vanadium redox flow batteries as an example to illustrate the method of the present invention in detail.

[0058] In the following embodiments, the PZT-4 piezoelectric ceramic sheet was purchased from Shandong Xinming Electronics Co., Ltd. The PZT-4 piezoelectric ceramic sheet used in Embodiment 9 has a length × width × thickness of 20 × 20 × 2 mm, while the PZT-4 piezoelectric ceramic sheet used in the other embodiments has a length × width × thickness of 40 × 40 × 2 mm. The signal generator is model DG1022Z, purchased from Riggen Power Electronics Co., Ltd.; the power amplifier is model ATA-1222A, purchased from Xi'an Antai Electronic Technology Co., Ltd.; the charge / discharge tester is model A211-BTS-4S-1U, purchased from Shenzhen Xinwei Electronics Co., Ltd.; the digital thermometer is model HH806AU, purchased from OMEGA Industrial Measurement Co., Ltd.; the low-temperature constant temperature water bath is model DC-1015, purchased from Shanghai Hengping Instrument Factory; the end plate is purchased from Dalian Deyue Co., Ltd.; and the polypropylene (PP) bipolar plate is provided by Jiaxing Naco New Materials Co., Ltd. The electrolyte solution was purchased from Dalian Borong New Materials Co., Ltd.

[0059] Example 1

[0060] In this embodiment, an ultrasound-assisted vanadium redox flow battery is assembled and its performance is tested.

[0061] (1) Figure 1 A schematic diagram of an ultrasonic-assisted vanadium redox flow battery is shown. The structure of this battery is basically the same as that of a conventional vanadium redox flow battery, except that an ultrasonic transducer is fixedly mounted on the side of the bipolar plates of both the positive and negative half-cells near the current collector, as detailed below:

[0062] according to Figure 1The structure shown is used for battery assembly. The ultrasound-assisted vanadium redox flow battery consists of a positive half-cell and a negative half-cell, which are separated by an ion-exchange membrane. Both the positive and negative half-cells include a porous electrode 6, an electrode frame 5, a bipolar plate 4, a current collector 2, an end plate 1, and an ultrasonic transducer 7. The bottom and top of the end plate 7 are respectively provided with an electrolyte inlet and an electrolyte outlet.

[0063] The ion exchange membrane used is specifically... The 115 ion exchange membrane (DuPont Ltd.) uses an ultrasonic transducer made of PZT-4 piezoelectric ceramic sheet with dimensions of 40×40×2mm. The end plates are made of aluminum alloy, the current collectors are made of copper, the electrode frames are made of polyvinyl chloride (PVC), the bipolar plates are made of 0.9mm thick polypropylene (PP), and the porous electrodes are carbon felt electrodes.

[0064] An unactivated carbon felt electrode is inserted into the electrode frame and compressed to a thickness of 3.5 mm. The carbon felt electrode is 40 mm long and 40 mm wide. The carbon felt electrode is attached to the ion exchange membrane. The bipolar plate is attached to the carbon felt electrode. Mounting holes matching the shape and size of the piezoelectric ceramic sheet are provided on the current collector and end plate. A piezoelectric ceramic sheet is attached and fixed to the outer side of each bipolar plate (the middle position of the side of the bipolar plate closest to the current collector), so that the piezoelectric ceramic sheet is attached to the bipolar plate. The current collector is attached to the outer side of the bipolar plate. The end plate is provided on the outer side of the current collector (the side of the current collector that is not in contact with the bipolar plate). The two piezoelectric ceramic sheets can act independently on the two half cells.

[0065] (2) After the battery is assembled, use a peristaltic pump to dispense 35 mL of electrolyte solution at a rate of 10 mL / min. -1 The flow rate is delivered to the electrode reaction zone.

[0066] (3) Use a charge-discharge tester to test the battery performance.

[0067] Figure 2 This is a schematic diagram of the principle of ultrasound acting on a vanadium redox flow battery. Ultrasonic waves in the fluid cause the fluid particles to oscillate around their equilibrium positions. By applying ultrasound of appropriate intensity, an acoustic flow is generated in the sound field.

[0068] Example 2

[0069] In this embodiment, the flow field distribution within the negative electrode of the battery described in Example 1 is provided with and without ultrasound.

[0070] Using COMSOL simulation software, the electrolyte was calculated to be dispensed at a rate of 20 mL / min. -1The electrolyte velocity distribution within the negative electrode under conditions of ultrasonic treatment (simulated ultrasonic frequency of 1 MHz) and without ultrasonic treatment, and the flow field distribution at the mid-section of the negative electrode under ultrasonic treatment and without ultrasonic treatment are compared as shown in the figure. Figure 3 As shown.

[0071] Depend on Figure 3 It can be seen that, compared to the case without ultrasound, the streamlines of the electrolyte within the negative electrode changed significantly after ultrasound was applied. The electrolyte flow velocity generally increased, the dead zone within the flow field decreased, and the flow uniformity and average flow velocity of the electrolyte within the negative electrode were improved. Furthermore, along... Figure 3 Figure (A) shows a comparison of electrolyte flow rate distribution in the negative electrode with and without ultrasound, plotted along the diagonal line indicated by the dashed line. The results are as follows: Figure 4 As shown. By Figure 4 It is known that acoustic flow can increase the flow velocity within the negative electrode, especially along the diagonal and in the flow dead zone, effectively improving the electrolyte flow velocity in the negative electrode, which is highly beneficial for reducing concentration polarization. As demonstrated in this embodiment, by applying ultrasound using the method described in this invention, acoustic flow can increase the overall flow velocity of the negative electrode flow field, reduce the flow dead zone, thereby improving the uniformity of electrolyte distribution, and further helping to reduce internal concentration polarization and improve battery performance.

[0072] Example 3

[0073] In this embodiment, the entire experimental setup for an ultrasound-assisted vanadium redox flow battery is provided, and a schematic diagram of the experimental setup is shown below. Figure 5 As shown, it includes an ultrasonic-assisted vanadium redox flow battery 8, a signal generator 9, a power amplifier 10, a charge / discharge tester 11, a temperature control device 12 (the temperature control device is a constant temperature low-temperature water bath), a digital thermometer 13, and a peristaltic pump 14.

[0074] First, assemble the ultrasonic-assisted vanadium redox flow battery according to the procedure in Example 1. After assembly, a photograph of the ultrasonic-assisted vanadium redox flow battery (taken from one endplate) is shown below. Figure 6 As shown. Connect the output of the signal generator to the input of the power amplifier, and connect the output of the power amplifier to the input of the ultrasonic transducer; connect the electrolyte outlet of the positive half-cell to the positive electrolyte storage tank via a pipe, and then connect it to the electrolyte inlet of the positive half-cell via a peristaltic pump and pipe; connect the electrolyte outlet of the negative half-cell to the negative electrolyte storage tank via a pipe, and then connect it to the electrolyte inlet of the negative half-cell via a peristaltic pump and pipe; place the positive and negative electrolyte storage tanks inside the temperature control device; connect the positive and negative outputs of the charge / discharge tester to the positive and negative terminals of the ultrasonic-assisted vanadium redox flow battery, respectively; place the probe of the digital thermometer at the electrolyte outlets of the positive and negative half-cells.

[0075] After the entire experimental setup was completed, a peristaltic pump was used to dispense 35 mL of electrolyte solution (1.65 MV and 4.12 MH₂SO₄) at a rate of 10 mL / min. -1 The electrolyte is delivered to the electrode reaction zone at a flow rate of [missing information]. The experimental setup is run, and the battery performance is tested using a charge-discharge tester. When no temperature control device is used to regulate the electrolyte temperature, the battery temperature changes with ultrasonic treatment time under different intensities of ultrasound, as shown in the curves. Figure 7 As shown. When a temperature control device is used to control the temperature of the electrolyte, the set temperature of the temperature control device is shown under both ultrasonic and non-ultrasonic conditions. Figure 8 The relationship between the water bath temperature and the actual battery temperature is shown in the graph below. Figure 8 As shown.

[0076] Combination Figures 7-8 It can be seen that when temperature control is not applied, the battery temperature increases with the duration of ultrasonic application, and the higher the intensity of the applied ultrasound, the higher the battery temperature and the faster the temperature rises. When the temperature control device is activated, the temperature difference between applying ultrasound and not applying ultrasound is not particularly significant, indicating that when the temperature control device is activated, ultrasonic enhancement does not cause a significant increase in battery temperature.

[0077] Example 4

[0078] In this embodiment, a method for enhancing the chemical reaction of an all-vanadium redox flow battery based on localized ultrasound assistance is provided, and the steps are as follows:

[0079] (1) The experimental apparatus was built according to the operation of Example 3.

[0080] (2) Allow the battery to operate without ultrasonic treatment, controlling the electrolyte flow rate at 10 mL / min. -1 The current density is 110 mA cm⁻¹ -2 The temperature control device is turned on to control the battery operating temperature at 25°C. After the battery reaches cycle stability, the coulombic efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) of the battery are obtained. Then, the set temperature of the temperature control device is adjusted to control the battery operating temperature at 5°C, 15°C, 35°C, and 45°C respectively. After the battery reaches cycle stability, the CE, VE, and EE of the battery are obtained.

[0081] (3) Run the battery under ultrasonic conditions, controlling the electrolyte flow rate at 10 mL / min. -1 The current density is 110 mA cm⁻¹ -2The temperature control device is turned on to control the battery's operating temperature to 25℃. The input voltage of the control signal generator is 800mVpp and the power amplifier gain is 40dB. After the battery reaches cycle stability, the CE, VE, and EE of the battery are obtained. Then, the set temperature of the temperature control device is adjusted to control the battery's operating temperature to 5℃, 15℃, 35℃, and 45℃ respectively. After the battery reaches cycle stability, the CE, VE, and EE of the battery are obtained.

[0082] In this embodiment, the test results of CE, VE, and EE of the battery under different battery operating temperatures and when ultrasonication is applied are as follows: Figure 9 As shown, with increasing operating temperature, coulombic efficiency decreases regardless of whether ultrasound is applied, while voltage efficiency and energy efficiency increase. This is due to the influence of temperature on the thermodynamics and kinetics of the electrochemical reaction. As temperature rises, the movement of vanadium ions becomes more vigorous, leading to increased permeability of vanadium ions through the membrane, thus reducing coulombic efficiency. At low temperatures, the acoustic flow effect of ultrasound facilitates electrolyte mixing, thereby reducing concentration polarization and promoting improvements in battery energy efficiency and voltage efficiency. At high temperatures, ultrasound application causes a rapid decrease in coulombic efficiency, while voltage efficiency increases relatively slowly, directly resulting in a decrease in energy efficiency. This embodiment demonstrates that applying ultrasound at low temperatures can more effectively improve battery performance, while the effect of ultrasound is limited at high temperatures.

[0083] Example 5

[0084] In this embodiment, the negative electrode V is examined under different states of charge (SOC) and current densities, with and without ultrasonic action. 2+ The variation of the flow uniformity factor.

[0085] A model of ultrasound acting on a battery was created using COMSOL Multiphysics software, such as... Figure 10 As shown, COMSOL simulation software was then used to calculate the delivery of the electrolyte to the electrode reaction zone of the battery, while controlling the ultrasonic frequency at 1 MHz and the electrolyte flow rate at 20 mL / min. -1 SOC is 0.15, current density is 80mA / cm² -2 Under the given conditions, the sound field distribution and flow field distribution of ultrasound propagation within the electrode, and a schematic diagram of the effect of sound flow within the electrode are shown below. Figure 11 As shown, the sound field distribution and flow field distribution of ultrasound propagation within the electrode are as follows: Figure 12 The two figures (A) and (B) are shown. Figure 13 V on the inner middle section of the negative electrode with and without ultrasound 2+ Distribution comparison chart. (From...) Figure 13 It can be seen that by applying ultrasound using the method of the present invention, the acoustic flux is enhanced in the V in the negative electrode.2+ It improves the uniformity of the distribution and effectively enhances mass transfer within the flow dead zone of the negative electrode.

[0086] like Figure 14 As shown in the small diagram in the upper left corner, three measurement sections are taken along the thickness direction of the negative electrode. These three sections are numbered from closest to farthest from the ion membrane as Position 1, Position 2, and Position 3. The V values ​​at the three measurement sections are calculated under conditions of applied and unapplied ultrasound. 2+ Distribution uniformity factor, results as follows Figure 14 As shown. By Figure 14 It can be seen that after applying ultrasound, the acoustic flow can enhance the flow uniformity on all three measurement sections, that is, increase the V at the three measurement sections. 2+ The distribution is uniform, and the closer the location is to the piezoelectric ceramic sheet PZT-4 where ultrasound is applied, the more obvious the acoustic flow effect.

[0087] The delivery of electrolyte to the electrode reaction zone of the battery was calculated using COMSOL simulation software, while controlling the ultrasonic frequency at 1 MHz and the electrolyte flow rate at 20 mL / min. -1 The SOC is 0.15, and the current densities are 20, 60, and 100 mA / cm², respectively. -2 Under these conditions, the V on the intermediate cross-section inside the negative electrode 2+ Distribution uniformity factor, results as follows Figure 15 As shown.

[0088] The delivery of electrolyte to the electrode reaction zone of the battery was calculated using COMSOL simulation software, while controlling the ultrasonic frequency at 1 MHz and the electrolyte flow rate at 20 mL / min. -1 The current density is 80 mA cm⁻¹ -2 Under conditions of SOC of 0.15, 0.45, and 0.75, respectively, the V on the intermediate cross-section inside the negative electrode 2+ Distribution uniformity factor, results as follows Figure 16 As shown.

[0089] Depend on Figures 15-16 It can be seen that under high current density and low SOC conditions, the application of ultrasound showed a more superior flow field regulation capability, mainly due to the intensified concentration polarization within the electrode at this time.

[0090] Example 6

[0091] In this embodiment, a method for enhancing the chemical reaction of an all-vanadium redox flow battery based on localized ultrasound assistance is provided, and the steps are as follows:

[0092] (1) The experimental apparatus was built according to the operation of Example 3.

[0093] (2) Allow the battery to operate without ultrasonic treatment, controlling the electrolyte flow rate at 10 mL / min. -1 The current density is 110 mA cm⁻¹ -2 The temperature control device is turned on to control the battery's operating temperature to 25°C. After the battery has reached cycle stability, the CE, VE, and EE of the battery are obtained.

[0094] (3) Run the battery under ultrasonic conditions, controlling the electrolyte flow rate at 10 mL / min. -1 The current density is 110 mA cm⁻¹ -2 The ultrasonic signal generator input voltage is controlled at 100-1500mVpp, the power amplifier gain is controlled at 40dB, and the temperature control device is activated to control the battery operating temperature at 25℃. The relationship between the signal generator output voltage and the piezoelectric ceramic sheet PZT-4 output voltage at this time is as follows: Figure 17 As shown. When the input voltage of the ultrasonic signal generator is 400mVpp, 600mVpp, 800mVpp, 1000mVpp, and 1200mVpp, the CE, VE, and EE of the battery are obtained after the battery has reached cycle stability. The results are as follows. Figure 18 As shown.

[0095] Example 7

[0096] In this embodiment, a method for enhancing the chemical reaction of an all-vanadium redox flow battery based on localized ultrasound assistance is provided, and the steps are as follows:

[0097] (1) The experimental apparatus was built according to the operation of Example 3.

[0098] (2) Allow the battery to operate without ultrasonic treatment, controlling the electrolyte flow rate at 10 mL / min. -1 The current density is controlled at 50mA / cm² respectively. -2 100mA cm -2 150mA cm -2 200mA cm -2 250mA cm -2 The temperature control device is activated to control the battery's operating temperature at 25°C. After the battery reaches cycle stability, the CE, VE, and EE of the battery are obtained.

[0099] (3) Run the battery under ultrasonic conditions, controlling the electrolyte flow rate at 10 mL / min. -1 The current density is controlled at 50mA / cm² respectively. -2 100mAcm -2 150mA cm -2 200mAcm -2 250mA cm -2The input voltage of the control signal generator was set to 800mVpp, and the power amplifier gain was set to 40dB. After the battery reached cycle stability, the CE, VE, and EE of the battery were obtained, and the results are as follows: Figure 19 As shown.

[0100] Example 8

[0101] In this embodiment, the effect of the ultrasonic application position on battery efficiency is investigated by adjusting the position of the piezoelectric ceramic sheet to which ultrasound is applied.

[0102] (1) The experimental setup was constructed according to the operation of Example 3. The difference between this example and Example 3 is that, when assembling the ultrasonic-assisted vanadium redox flow battery, the 40×40×2mm PZT-4 piezoelectric ceramic sheet was replaced with four 20×20×2mm sheets. That is, the location where a 40×40×2mm piezoelectric ceramic sheet was installed in Example 1 was changed to four 20×20×2mm piezoelectric ceramic sheets, and the four piezoelectric ceramic sheets were allowed to work independently. Figure 20 As shown.

[0103] (2) Allow the battery to operate without ultrasonic treatment, controlling the electrolyte flow rate at 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 The temperature control device is activated to maintain the battery's operating temperature at 25°C. After the battery reaches stable cycle conditions, the CE, VE, and EE values ​​are obtained. No ultrasound is applied during this step. Figure 21 As shown in Figure (A).

[0104] (3) Run the battery under ultrasonic conditions, controlling the electrolyte flow rate at 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 The temperature control device is activated to maintain the battery operating temperature at 25°C. The input voltage of the control signal generator is set to 800mVpp, and the power amplifier gain is set to 40dB. Figure 21 In the manner shown in Figure (B), ultrasonic waves were applied to the dead zone of the electrode flow, and the CE, VE, and EE of the battery were obtained after the battery had reached cycle stability.

[0105] (3) Run the battery under ultrasonic conditions, controlling the electrolyte flow rate at 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 The temperature control device is activated to maintain the battery operating temperature at 25°C. The input voltage of the control signal generator is set to 800mVpp, and the power amplifier gain is set to 40dB. Figure 21The ultrasonic waves were applied to the electrode flow dead zone in the manner shown in Figure (C), and the CE, VE, and EE of the battery were obtained after the battery had been running until it reached cycle stability.

[0106] The CE, VE, and EE test results of the battery in this embodiment are as follows: (The original text appears to be incomplete and contains errors. A more accurate translation would require the full context.) Figure 22 As shown, Figure 22 In the diagram, a, b, and c represent the test results when ultrasound was not applied in step (1), and when ultrasound was applied in steps (2) and (3), respectively. Figure 22 It can be seen that the location where ultrasound is applied has a significant impact on the voltage efficiency and energy efficiency of the battery. When ultrasound acts more fully on the flow dead zone of the electrode, it has a more significant improvement on voltage efficiency and energy efficiency.

[0107] Example 9

[0108] In this embodiment, the effect of the ultrasound application strategy on battery temperature and energy consumption is investigated by adjusting the ultrasound application strategy.

[0109] (1) The experimental apparatus was built according to the operation of Example 3.

[0110] (2) Figure 23 As shown in Figure (A), in this step, no ultrasound is applied during either the charging or discharging phases, and the electrolyte flow rate is controlled at 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 Without turning on the temperature control device to control the temperature, after the battery has run to cycle stability, the CE, VE and EE of the battery, as well as the temperature change of the battery and the energy consumption (power consumption) of the battery are obtained.

[0111] (3) Figure 23 As shown in Figure (A) by method b, this step involves continuous ultrasonic application during the charging phase and no ultrasonic application during the discharging phase, while controlling the electrolyte flow rate to 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 Temperature control was not activated. When ultrasound was applied, the input voltage of the control signal generator was 800mVpp and the power amplifier gain was 40dB. After the battery reached cycle stability, the battery's CE, VE, and EE, as well as the battery's temperature changes and energy consumption, were obtained.

[0112] (4) Figure 23 As shown in Figure (A) c, this step involves no ultrasound application during the charging phase, but continuous ultrasound application during the discharging phase, with the electrolyte flow rate controlled at 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2Temperature control was not activated. When ultrasound was applied, the input voltage of the control signal generator was 800mVpp and the power amplifier gain was 40dB. After the battery reached cycle stability, the battery's CE, VE, and EE, as well as the battery's temperature changes and energy consumption, were obtained.

[0113] (5) Figure 23 As shown in Figure (A), step d involves applying ultrasound in a pulsed manner during the charging phase and not applying ultrasound during the discharging phase, while controlling the electrolyte flow rate to 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 Temperature control was not activated. When ultrasound was applied, the input voltage of the control signal generator was 800mVpp and the power amplifier gain was 40dB. After the battery reached cycle stability, the battery's CE, VE, and EE, as well as the battery's temperature changes and energy consumption, were obtained.

[0114] (6) Figure 23 As shown in Figure (A) with application method e, this step does not apply ultrasound during the charging phase, but applies ultrasound in a pulsed manner during the discharging phase, controlling the electrolyte flow rate to 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 Temperature control was not activated. When ultrasound was applied, the input voltage of the control signal generator was 800mVpp and the power amplifier gain was 40dB. After the battery reached cycle stability, the battery's CE, VE, and EE, as well as the battery's temperature changes and energy consumption, were obtained.

[0115] (7) Figure 23 As shown in Figure (A), in this step, ultrasound is continuously applied during both the charging and discharging phases, while controlling the electrolyte flow rate at 10 mL / min. -1 The controlled current density is 110 mA cm⁻¹ -2 Temperature control was not activated. When ultrasound was applied, the input voltage of the control signal generator was 800mVpp and the power amplifier gain was 40dB. After the battery reached cycle stability, the battery's CE, VE, and EE, as well as the battery's temperature changes and energy consumption, were obtained.

[0116] In this embodiment, under the condition that the temperature control device is not activated for temperature control, the temperature change and energy consumption of the battery under different ultrasonic application strategies are as follows: Figure 23 Figures (B) and (C) show the test results of CE, VE, and EE of the battery under different ultrasonic application strategies. Figure 24 As shown. By Figures 23-24It can be seen that, without the temperature control device activated, the battery temperature rises with the application of ultrasound and falls when the ultrasound application stops; the battery's energy consumption increases with the duration of ultrasound application. Overall, applying ultrasound in a pulsed manner can effectively reduce power consumption while improving the battery's voltage efficiency and energy efficiency.

[0117] Example 10

[0118] In this embodiment, the flow field distribution inside the negative electrode of a battery is tested with and without ultrasound at an industrial-scale porous electrode size. A comparison of the sizes of industrial-scale and laboratory-scale porous electrodes is provided. Figure 25 As shown, the laboratory-scale porous electrode (Examples 1-9) has dimensions (length × width) of 40mm × 40mm, while the industrial-scale porous electrode has dimensions (length × width) of 600mm × 240mm. A model of a battery (with a structure basically the same as in Example 1, but larger) subjected to ultrasonic treatment on the industrial-scale porous electrode was created using COMSOL Multiphysics software. Figure 26 As shown, the electrolyte flow rate was controlled at 20 mL / min. -1 Under the condition of ultrasonic frequency of 1MHz, the flow field distribution inside the negative electrode is simulated with and without ultrasonic waves. The comparison diagram of the flow field and streamlines on the middle section of the negative electrode is shown below. Figure 27 As shown.

[0119] Depend on Figure 27 It can be seen that for porous electrodes on an industrial scale, compared with the case without ultrasonication, the electrolyte flow rate is significantly increased after ultrasonication is applied, the electrolyte streamline is significantly changed, the dead area in the flow field is reduced, and the flow uniformity and average flow rate of the electrolyte are effectively improved, which will significantly reduce the concentration polarization inside the battery.

[0120] The average flow rate of the electrolyte in the negative electrode before and after ultrasonication is compared between the laboratory-scale and industrial-scale porous electrode conditions of Example 2 and this example. Figure 28As shown in the figure, due to the size limitations of the porous electrode in laboratory settings, the non-uniformity of electrolyte concentration within the porous electrode is not significant. Therefore, the effect of ultrasound on promoting electrolyte flow is relatively limited. The average flow velocity of the electrolyte within the negative electrode only increases from 1.44 mm / s without ultrasound to 3.26 mm / s. However, in industrial-scale porous electrode settings, the non-uniformity of electrolyte flow within the negative electrode is even more severe. In this case, ultrasound can significantly improve the electrolyte flow velocity. After applying ultrasound, the average flow velocity of the electrolyte within the porous electrode can be increased from 1.23 mm / s to 18.19 mm / s. This embodiment demonstrates that applying ultrasound using the method described in this invention can effectively improve the overall flow velocity of flow batteries in industrial-scale applications, reduce dead zones, and thus improve electrolyte uniformity, thereby enhancing the performance of flow batteries in industrial-scale applications.

Claims

1. A method for enhancing the chemical reaction of a flow battery based on localized ultrasound-assisted localization, characterized in that, The steps are as follows: (1) Mounting holes are provided on the current collectors and end plates of the positive and negative half-cells of the flow battery. The mounting holes are matched with ultrasonic transducers. Ultrasonic transducers are provided on the bipolar plates of the positive and negative half-cells of the flow battery. The ultrasonic transducers are placed against the side of the bipolar plates close to the current collector. The surface of the ultrasonic transducer in contact with the bipolar plates has a planar structure. The position of the ultrasonic transducer on the bipolar plates and the size of the ultrasonic transducer should ensure that the area of ​​action of the ultrasonic waves applied by the ultrasonic transducer covers the flow dead zone inside the porous electrode. The acoustic impedance of the bipolar plate is matched with the ultrasound applied by the ultrasonic transducer, and the thickness of the bipolar plate is matched with half the wavelength of the ultrasound applied by the ultrasonic transducer. (2) Connect the output of the signal generator to the input of the power amplifier, and connect the output of the power amplifier to the input of the ultrasonic transducer. (3) Turn on the electrolyte pump of the flow battery to pump electrolyte to the positive half cell and the negative half cell to run the flow battery. During the operation of the flow battery, turn on the signal generator and power amplifier to apply ultrasound to the flow battery through the ultrasonic transducer. Use ultrasound to improve the flow rate and flow uniformity of the electrolyte in the porous electrode and enhance the chemical reaction of the flow battery.

2. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to claim 1, characterized in that, In step (3), during the operation of the flow battery, the temperature of the positive electrode electrolyte and the negative electrode electrolyte is regulated by a temperature control device.

3. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to claim 2, characterized in that, During the operation of the flow battery, the temperature of the positive and negative electrolytes is controlled between 0 and 50°C by a temperature control device.

4. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to claim 1, characterized in that, The ultrasonic transducers, located on the positive half-cell and the bipolar plates on the negative half-cell, operate independently.

5. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to claim 4, characterized in that, At least one ultrasonic transducer is installed on the bipolar plate of the positive half-cell. When the number of ultrasonic transducers installed on the bipolar plate of the positive half-cell is ≥2, each ultrasonic transducer works independently. At least one ultrasonic transducer is installed on the bipolar plate of the negative half-cell. When the number of ultrasonic transducers installed on the bipolar plate of the negative half-cell is ≥2, each ultrasonic transducer works independently.

6. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to any one of claims 1 to 5, characterized in that, The ultrasonic transducer includes at least one of a piezoelectric ultrasonic transducer and an electromagnetic acoustic transducer.

7. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to claim 6, characterized in that, The piezoelectric ultrasonic transducer includes a piezoelectric ceramic sheet, a sandwich ultrasonic transducer, or an interdigital transducer.

8. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to any one of claims 1 to 5, characterized in that, An ultrasonic transducer is placed on a bipolar plate corresponding to the flow dead zone of a porous electrode. The total area of ​​the contact surface between all ultrasonic transducers placed on the same bipolar plate and the bipolar plate is denoted as A1, the area of ​​the surface of the porous electrode in contact with the bipolar plate is denoted as A0, and the area of ​​the flow dead zone inside the porous electrode in contact with the bipolar plate is denoted as A2. A1:A0 = (A2 / A0 ~ 1.2):

1.

9. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to any one of claims 1 to 5, characterized in that, During the operation of the flow battery, the vibration frequency of the ultrasonic transducer is controlled to be 0.02–10 MHz.

10. The method for enhancing the chemical reaction of a flow battery based on localized ultrasound assistance according to any one of claims 1 to 5, characterized in that, Ultrasound is applied intermittently during the operation of the flow battery.

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