Detection device for water migration volume of flow battery

Abstract

The utility model discloses a flow battery water migration amount detection device, the detection device comprises a reaction unit, a separation unit and a measurement unit, the reaction unit comprises a flow battery, and the flow battery is provided with an electrolyte inlet and an electrolyte outlet; the separation unit is provided with a first cavity, and a first liquid inlet, a first liquid outlet, a first gas inlet and a second gas outlet are formed in the first cavity; the measuring unit is provided with a second cavity and an observation pipe, and the second cavity is provided with a second liquid inlet and a second liquid outlet. According to the detection device, through the arrangement of the separation unit, gas in the electrolyte can be separated out, the internal gas is prevented from influencing subsequent measurement, the measurement unit is easy to operate, the electrolyte is easy to add through the observation pipe, and the water migration amount condition is visually observed.

Description

Technical Field

[0001] The present application mainly relates to the field of liquid flow batteries, and in particular to a device for detecting water migration in liquid flow batteries. Background Art

[0002] All-vanadium redox flow batteries (abbreviated as vanadium batteries, VRFB) have excellent safety, reliability, cycle life and other performances, and have broad application prospects in the fields of new energy power generation and smart grid construction. Compared with other redox flow battery technologies, vanadium batteries use the same type of positive and negative electrolyte solutions, with only different valence states of vanadium ions (the positive electrode is V 4+ and V 5+ , the negative electrode is V 2+ and V 3+ ) as the electrolyte active material, largely avoiding contamination of the positive and negative electrolyte active materials. However, during the long-term operation of the battery system, water molecules and vanadium ions at the positive and negative electrodes of the proton membrane will be transported across the membrane under the action of osmotic pressure, causing an imbalance in the volume and valence of the positive and negative electrolyte solutions. In addition, when the vanadium battery reaches a certain level of charge, the high concentration of divalent vanadium ions at the negative electrode will react with the hydrogen ions in the electrolyte to produce hydrogen. The reaction formula is as follows:

[0003] V 2+ +H + →V 3+ +H2↑.

[0004] The transmembrane transport of vanadium ions and the hydrogen evolution reaction at the negative electrode reduce the system's discharge capacity. Therefore, in engineering applications, a remixing method is often used to restore the capacity of vanadium batteries. This advantage of continuous regeneration can significantly reduce the cost of vanadium battery energy storage systems over their entire lifecycle. However, during actual operation, the migration of water molecules in vanadium batteries is difficult to monitor in real time, making it impossible to perform remixing operations in time to restore the volume and valence of the electrolyte solution. A detection device that can dynamically and intuitively monitor the migration of water molecules in real time is urgently needed. Utility Model Content

[0005] This application addresses the technical problem in the prior art that the amount of water molecules migrated in a liquid flow battery cannot be detected in real time, and provides a detection device for a liquid flow battery that can intuitively detect the amount of water migrated in the liquid flow battery at different charging and discharging stages.

[0006] In order to solve the above technical problems, the present application provides a device for detecting the water migration amount of a liquid flow battery, comprising: a reaction unit, a separation unit and a measuring unit, wherein the reaction unit includes a liquid flow battery, and the liquid flow battery has an electrolyte inlet and an electrolyte outlet; the separation unit has a first cavity, and the first cavity is provided with a first liquid inlet, a first liquid outlet, a first gas inlet and a second gas outlet, the first liquid inlet is connected to the electrolyte outlet, the first gas inlet is used to pass a purge gas into the first cavity, and the second gas outlet is used to discharge the gas in the first cavity; the measuring unit has a second cavity and an observation tube, and the second cavity is provided with a second liquid inlet and a second liquid outlet, the second liquid inlet is connected to the first liquid outlet, and the second liquid outlet is connected to the electrolyte inlet, the observation tube has a first end and a second end, the first end is connected to the second cavity, and the second end is connected to the atmospheric environment.

[0007] In one embodiment of the present application, the second liquid outlet and the electrolyte inlet are connected through a first pipe, and a first flow meter is provided on the first pipe; the first liquid outlet and the second liquid inlet are connected through a second pipe, and a second flow meter is provided on the second pipe.

[0008] In one embodiment of the present application, a first pump is further provided on the first pipeline, and the first pump is used to drive the electrolyte to flow from the second liquid outlet to the electrolyte inlet; a second pump is also provided on the second pipeline, and the second pump is used to drive the electrolyte to flow from the first liquid outlet to the second liquid inlet.

[0009] In one embodiment of the present application, the first liquid inlet and the electrolyte outlet are connected through a third pipe, and a first pressure gauge is provided on the third pipe.

[0010] In one embodiment of the present application, a second pressure gauge is provided on the first cavity, and the second pressure gauge is used to measure the pressure inside the first cavity.

[0011] In one embodiment of the present application, a stirring device is provided in the first cavity, and the stirring device is used to stir the electrolyte in the first cavity to allow the gas in the electrolyte to escape.

[0012] In one embodiment of the present application, the observation tube is a transparent straight tube, and a scale is provided on the observation tube.

[0013] In one embodiment of the present application, the reaction unit further includes a charging and discharging device, which is connected to the liquid flow battery and is used to control the charging and discharging of the liquid flow battery.

[0014] In one embodiment of the present application, the flow battery has a positive electrode and a negative electrode, the electrolyte inlet includes a first electrolyte inlet and a second electrolyte inlet, and the electrolyte outlet includes a first electrolyte outlet and a second electrolyte outlet, wherein the first electrolyte inlet and the first electrolyte outlet are arranged at the positive electrode, and the second electrolyte inlet and the second electrolyte outlet are arranged at the negative electrode; wherein the first group of separation units and the measuring unit are arranged at the negative electrode, and the second group of separation units and the measuring unit are arranged at the positive electrode.

[0015] In one embodiment of the present application, a first mixing pipe is provided between the first liquid outlet of the first group and the first liquid inlet of the second group, and a first valve is provided on the first mixing pipe; a second mixing pipe is provided between the first liquid inlet of the first group and the first liquid outlet of the second group, and a second valve is provided on the second mixing pipe.

[0016] In one embodiment of the present application, the observation tube has a first volume, the second cavity has a second volume, and the first volume accounts for 10% to 20% of the second volume.

[0017] The detection device of this application, by providing a separation unit, can separate the gas in the electrolyte, preventing the internal gas from affecting subsequent measurements. The measurement unit is simple to operate, and the observation tube makes it easy to add electrolyte and visually observe the amount of water migration. The technical effect is that the detection device has a flexible design, simple operation, and is not prone to errors. The specifications and structure of the liquid flow battery can be changed according to actual operating conditions, and the flow rate of the electrolyte can be adjusted to detect the amount of water migration in different charge and discharge stages in real time, dynamically, and intuitively. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the present application. They are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present application and, together with this specification, serve to explain the principles of the present application. In the accompanying drawings:

[0019] Figure 1 This is a schematic diagram of a detection device provided in one embodiment of the present application;

[0020] Figure 2 is a schematic diagram of a second cavity provided in one embodiment of the present application;

[0021] Figure 3 This is a schematic diagram of a detection device provided in one embodiment of the present application.

[0022] Reference numerals: flow battery, 100; electrolyte inlet, 101; electrolyte outlet, 102; first cavity, 200; second pressure gauge, 201; stirring device, 202; first liquid inlet, 203; first liquid outlet, 204; first gas inlet, 205; second gas outlet, 206; second cavity, 300; second liquid inlet, 301; second liquid outlet, 302; observation tube, 303; first end, 304; second end, 305; first volume, 306; second volume, 307; First pipeline, 400; first flowmeter, 401; first pump, 402; second pipeline, 500; second flowmeter, 501; second pump, 502; third pipeline, 600; first pressure gauge, 601; first mixing pipeline, 701; first valve, 702; second mixing pipeline, 801; second valve, 802; first group, 700; second group, 800; first electrolyte inlet, 1011; second electrolyte inlet, 1012; first electrolyte outlet, 1021; second electrolyte outlet, 1022. DETAILED DESCRIPTION

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0024] As used herein, unless the context clearly indicates otherwise, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0025] Unless otherwise specified, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. Technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0026] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. Furthermore, while the terms used in this application are selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, this application should be understood not only by the actual terms used, but also by the meaning implied by each term.

[0027] like Figure 1 As shown, an embodiment of the present application provides a device for detecting water migration in a flow battery. The device includes a reaction unit, a separation unit, and a measurement unit. The reaction unit includes a flow battery 100 having an electrolyte outlet 102 and an electrolyte inlet 101.

[0028] In one embodiment of the present application, the flow battery 100 may be a single cell or a battery pack. A single cell also includes components such as end plates, bipolar plates, gaskets, graphite cores, and exchange membranes. This application does not limit the specific structure of a single cell; most single cells are suitable for use in the water migration detection device of this application. A battery pack is a flow battery 100 formed by combining multiple single cells. Preferably, the flow battery 100 is an all-vanadium flow battery 100.

[0029] In one embodiment of the present application, the electrolyte inlet 101 of the flow battery 100 is lower than the electrolyte outlet 102. This configuration helps the electrolyte fully cover the exchange membrane in the flow battery 100, thereby improving the reaction rate of the redox reaction and the exchange efficiency of positive and negative electrons.

[0030] See also Figure 1The separation unit has a first cavity 200, which is provided with a first liquid inlet 203, a first liquid outlet 204, a first gas inlet 205 and a second gas outlet 206. The first liquid inlet 203 is connected to the electrolyte outlet 102, the first gas inlet 205 is used to pass a purge gas into the first cavity 200, and the second gas outlet 206 is used to discharge the gas in the first cavity 200. The purge gas can be an inert gas, such as argon and helium, or nitrogen. The introduction of the purge gas can prevent the entry of oxidizing gas into the liquid flow battery 100 and prevent unnecessary oxidation reactions. The liquid flow battery 100 will also undergo a hydrogen evolution reaction. If the liquid flow battery 100 undergoes a hydrogen evolution reaction, the hydrogen in the first cavity 200 is discharged through the purge gas, thereby improving the safety of the detection device. In addition, the extra hydrogen will also cause the air pressure in the first cavity 200 to increase. Discharging the hydrogen through the purge gas can also maintain the pressure in the first cavity 200 within a stable range. The volume flow rate of the purge gas can be controlled according to the scale of the battery. For example, when the electrode area of ​​the flow battery 100 is 48 square centimeters, the volume flow rate of the purge gas is controlled at 0.1-0.5 L / min.

[0031] In one embodiment of the present application, the first gas inlet 205 and the second gas outlet 206 are positioned relative to each other at the top of the first chamber 200, and are positioned at the same height. The height of the first gas inlet 205 and the second gas outlet 206 from the top of the chamber is 5-10% of the total height of the first chamber 200. Positioning the first gas inlet 205 and the second gas outlet 206 relative to each other at the same height at the top of the first chamber 200 facilitates the discharge of hydrogen, as hydrogen has a low density and tends to accumulate at the top of the first chamber 200.

[0032] refer to Figure 1-2 As shown, the measurement unit includes a second chamber 300 and an observation tube 303. The second chamber 300 is provided with a second liquid inlet 301 and a second liquid outlet 302. The second liquid inlet 301 is connected to the first liquid outlet 204, and the second liquid outlet 302 is connected to the electrolyte inlet 101. The observation tube 303 has a first end 304 and a second end 305. The first end 304 communicates with the second chamber 300, and the second end 305 communicates with the atmosphere. The communication between the observation tube 303 and the atmosphere stabilizes the pressure in the second chamber 300, resulting in more accurate readings obtained through the observation tube 303.

[0033] In one embodiment of the present application, the second liquid outlet 302 and the electrolyte inlet 101 are connected through a first pipe 400, and a first flowmeter 401 is provided on the first pipe 400. The first liquid outlet 204 and the second liquid inlet 301 are connected through a second pipe 500, and a second flowmeter 501 is provided on the second pipe 500.

[0034] In one embodiment of the present application, a first pump 402 is further provided on the first pipeline 400, and the first pump 402 is used to drive the electrolyte to flow from the second liquid outlet 302 to the electrolyte inlet 101; a second pump 502 is also provided on the second pipeline 500, and the second pump 502 is used to drive the electrolyte to flow from the first liquid outlet 204 to the second liquid inlet 301.

[0035] In one embodiment of the present application, the rotational speeds of the first pump 402 and the second pump 502 can be adjusted as needed based on the readings of the first flowmeter 401 and the second flowmeter 501, thereby adjusting the volumetric flow rate. However, the present application does not limit the specific structures of the first pump 402, the second pump 502, and the first flowmeter 401 and the second flowmeter 501. As an example of the present application, the first pump 402 and the second pump 502 are configured as peristaltic pumps, and the first flowmeter 401 and the second flowmeter 501 are configured as volumetric flowmeters.

[0036] In one embodiment of the present application, the first liquid inlet 203 is connected to the electrolyte outlet 102 via a third pipe 600, which is provided with a first pressure gauge 601. The first pressure gauge 601 is used to eliminate the influence of pressure drop and volume flow rate differences in the pipe on the test results. Preferably, the first pipe 400, the second pipe 500, and the third pipe 600 are made of a material resistant to strong acid corrosion, such as polytetrafluoroethylene and rigid polyvinyl chloride.

[0037] In one embodiment of the present application, a second pressure gauge 201 is provided on the first cavity 200 to measure the pressure within the first cavity 200. As previously described, the first cavity 200 is used to discharge gases, such as hydrogen, from the flow battery 100. The second pressure gauge 201 can be used to determine the internal pressure of the first cavity 200, thereby preventing fluctuations in the reading on the observation tube 303 caused by the presence of gas. As an example of the present application, the first pressure gauge 601 and the second pressure gauge 201 are precision pressure gauges.

[0038] In one embodiment of the present application, a stirring device 202 is provided in the first cavity 200. The stirring device 202 is used to stir the electrolyte in the first cavity 200 to allow the gas in the electrolyte to escape. It can also be used to uniformly distribute the concentration of the electrolyte. Figure 1 As shown, the stirring device 202 can be a paddle, which is disposed at the bottom of the first cavity 200. In other embodiments, the stirring device 202 can also be disposed on the inner wall of the first cavity 200, near the bottom. The number of stirring devices 202 can be one or more, and can be disposed at different locations.

[0039] In one embodiment of the present application, the stirring speed of the stirring device 202 can also be freely adjusted according to the speed of the first pump 402 and the second pump 502. The higher the speed of the first pump 402 and the second pump 502, the higher the stirring speed of the stirring device 202, and the two are positively correlated.

[0040] In one embodiment of the present application, the observation tube 303 is a transparent straight tube, and a scale is provided on the observation tube 303. Setting the observation tube 303 as a transparent straight tube and marking it with a scale allows the reading of the observation tube 303 to be obtained clearly and quickly.

[0041] In one embodiment of the present application, the observation tube 303 has a first volume, the second cavity 300 has a second volume, and the first volume accounts for 10% to 20% of the second volume. This numerical setting can prevent the electrolyte from overflowing from the observation tube 303 when water migration occurs.

[0042] In one embodiment of the present application, the observation tube 303 and the second cavity 300 are integrally cast, with a scale accuracy of 0.1 mm. The observation tube 303 and the second cavity 300 can be made of borosilicate glass, tempered glass, perfluoroalkoxy polymer, fluorinated ethylene propylene copolymer, etc.

[0043] In one embodiment of the present application, the reaction unit further includes a charging and discharging device (not shown), which is connected to the flow battery 100 and is used to control the charging and discharging of the flow battery 100. The charging and discharging device can adjust the current density of the flow battery 100 to obtain the amount of water migration at different current densities.

[0044] refer to Figure 3 As shown, in one embodiment of the present application, the liquid flow battery 100 has a positive electrode and a negative electrode, the electrolyte inlet 101 includes a first electrolyte inlet 1011 and a second electrolyte inlet 1012, and the electrolyte outlet 102 includes a first electrolyte outlet 1021 and a second electrolyte outlet 1022, wherein the first electrolyte inlet 1011 and the first electrolyte outlet 1021 are arranged at the positive electrode, and the second electrolyte inlet 1012 and the second electrolyte outlet 1022 are arranged at the negative electrode; wherein the first group 700 separation units and the measuring units are arranged at the negative electrode, and the second group 800 separation units and the measuring units are arranged at the positive electrode.

[0045] In one embodiment of the present application, the first pipe 400 , the second pipe 500 and the third pipe 600 of the first group 700 and the second group 800 are of equal length to ensure that the initial volumes of electrolyte introduced into the positive and negative electrodes are equal.

[0046] In one embodiment of the present application, a first mixing conduit 701 is disposed between the first liquid outlet 204 of the first group 700 and the first liquid inlet 203 of the second group 800, and a first valve 702 is provided on the first mixing conduit 701. A second mixing conduit 801 is disposed between the first liquid inlet 203 of the first group 700 and the first liquid outlet 204 of the second group 800, and a second valve 802 is provided on the second mixing conduit 801. The first mixing conduit 701 and the second mixing conduit 801 allow the electrolytes of the positive and negative electrodes to be mixed when a significant shift in water migration occurs in the flow battery 100, thereby achieving a balance in volume and valence between the electrolytes. Preferably, the first mixing conduit 701 and the second mixing conduit 801 are made of a material resistant to strong acid corrosion, such as polytetrafluoroethylene (PTFE) or rigid polyvinyl chloride (PVC).

[0047] In one embodiment of the present application, the aperture of the first liquid inlet 203 and the first liquid outlet 204 of the first cavity 200 is D1, the aperture of the second liquid inlet 301 and the second liquid outlet 302 of the second cavity 300 is D2, and the aperture of the first pipe 400, the second pipe 500, the third pipe 600, the first mixing pipe 701 and the second mixing pipe 801 is D3, D1=D2=D3, and the aperture size is 3-5 mm.

[0048] In one embodiment of the present application, the connections between the first pipe 400, the second pipe 500, the third pipe 600, the first mixing pipe 701 and the second mixing pipe 801 are all connected and sealed by ferrule nuts and O-rings, and the entire detection device is in a closed state.

[0049] Based on the aforementioned device for detecting water migration in a flow battery, the following describes a method for using the device, which includes the following steps:

[0050] S101, filling the second cavities 300 of the first group 700 and the second cavities 300 of the second group 800 with electrolyte;

[0051] S102, allowing the electrolyte in the second cavity 300 to flow into the flow battery 100 through the electrolyte inlet 101, the electrolyte filling the flow battery 100 and flowing back to the second cavity 300 through the electrolyte outlet 102;

[0052] S103, turning off the first pump 402 on the first pipe 400 and the second pump 502 on the second pipe 500, wherein the first pipe 400 is used to connect the second liquid outlet 302 and the electrolyte inlet 101, and the second pipe 500 is used to connect the first liquid outlet 204 and the second liquid inlet 301;

[0053] S104, injecting electrolyte into the second cavity 300 through the observation tube 303, so that the initial liquid level in the observation tube 303 of the first group 700 is equal to the initial liquid level in the observation tube 303 of the second group 800;

[0054] S105, turning on the first pump 402 and the second pump 502 to charge and discharge the flow battery 100;

[0055] S106 , after starting the first pump 402 and the second pump 502 , further includes: adjusting the rotation speeds of the first pump 402 and the second pump 502 to measure the water migration balance of the flow battery 100 at different volume flow rates of the electrolyte.

[0056] S107 , after starting the first pump 402 and the second pump 502 , the process further includes: inputting a purge gas into the first chamber 200 through the first gas inlet 205 .

[0057] S108 , after starting the first pump 402 and the second pump 502 , the process further includes: starting the stirring device 202 in the first cavity 200 .

[0058] S109. During the charge and discharge process, the current liquid level in the observation tube 303 of the first group 700 and the current liquid level in the observation tube 303 of the second group 800 are recorded. When the following formula is satisfied, it indicates that the water migration of the flow battery 100 has reached equilibrium:

[0059] ||V 10 -V 11 |-|V 20 -V 21 || <Th;

[0060] Among them, V 10 represents the initial liquid level in the observation tube 303 of the first group 700, V 20 represents the initial liquid level in the observation tube 303 of the second group 800, V 11 represents the current liquid level in the observation tube 303 of the first group 700, V 21 represents the current liquid level in the observation tubes 303 of the second group 800, and Th represents a preset threshold value.

[0061] The following describes steps S101 to S109 with reference to a specific example, taking the case where the first group 700 is connected to the positive electrode and the second group 800 is connected to the negative electrode.

[0062] In use, the operator first adds electrolyte to the positive and negative electrodes of the flow battery 100. A certain volume of electrolyte is slowly injected into the second cavity 300 through the second end 305 of the observation tube 303. The volumes of the electrolyte added to the positive and negative electrodes are equal until the second cavity 300 is just filled with electrolyte. Subsequently, the rotation speeds of the first pump 402 and the second pump 502 are opened and adjusted until the readings of the first volume flow meters and the second volume flow meters at the positive and negative electrodes of the flow battery 100 are the same, and the readings of the first pressure gauges 601 at the positive and negative electrodes are the same, and the readings of the second pressure gauges 201 at the positive and negative electrodes are also the same. When the first pipeline 400, the second pipeline 500, and the third pipeline 600 at the positive and negative electrodes are filled with electrolyte and the electrolyte can flow back to the second cavity 300 along the first pipeline 400, the second pipeline 500, and the third pipeline 600, the first pump 402 and the second pump 502 at the positive and negative electrodes are closed. Then, electrolyte is added to the positive and negative electrodes for the second time. The process of adding electrolyte is as follows: a certain volume of electrolyte is slowly injected into the second cavity 300 through the second end 305 of the observation tube 303 until the readings of the observation tubes 303 at the positive and negative electrodes are the same, and then the addition of electrolyte is stopped. At this time, since the positive and negative electrodes both use the same separation unit, measurement unit, and the first pipeline 400, the second pipeline 500, and the third pipeline 600 of equal length, and no redox reaction occurs, the total volumes of the electrolyte injected into the positive and negative electrodes are equal, and the initial liquid levels of the observation tubes 303 are also equal. After stopping the addition of electrolyte, the total volume V2 of the electrolyte added to the positive electrode and the total volume V1 of the electrolyte added to the negative electrode are recorded. And the initial liquid level V in the observation tube 303 of the negative electrode is recorded. 10 , and the initial liquid level V of the observation tube 303 of the positive electrode 20 . The first pump 402 and the second pump 502 at the positive and negative electrodes are started for the second time. The rotation speed of the stirring device 202 of the first cavity 200 is opened and adjusted. The first gas inlet 205 and the second gas outlet 206 of the first cavity 200 are opened, and nitrogen is introduced at a constant rate. After the adjustment is completed, the charge-discharge device is turned on, and a normal charge-discharge test is performed on the flow battery 100. During the charge-discharge test, the current liquid levels of the observation tubes 303 at the negative and positive electrodes are recorded. The current liquid level in the observation tube 303 of the negative electrode is denoted as V 11 , and the current liquid level in the observation tube 303 of the positive electrode is denoted as V 21 . When ||V 10 - V 11 | - Δ|V 20 - V 21 || < Th, the water migration amount of the flow battery 100 reaches equilibrium. Th is a preset threshold. In this example, Th is set to 0.1 ml, and || represents the absolute value. After reaching equilibrium, ||V 10 - V 11The value of | is the amount of water migration. To measure the water migration of the flow battery 100 at different current densities, the current density of the charge and discharge device can be changed, and normal charge and discharge can be performed several times in a cycle at each current density. For example, at a current density of 80 mA / cm 2 When the water migration reaches equilibrium, the water migration amount is recorded. Then the current density of the charge and discharge device is changed to 150mA / cm 2 , perform several charge and discharge cycles, and record the water migration amount after the water migration amount reaches equilibrium.

[0063] In one embodiment of the present application, step S102 further includes: filling the first mixing pipe 701 and the second mixing pipe 801 with electrolyte.

[0064] In one embodiment of the present application, step S103 also includes: closing the first valve 702 and the second valve 802; wherein, a first mixing pipe 701 is provided between the first liquid outlet 204 of the first group 700 and the first liquid inlet 203 of the second group 800, and the first valve 702 is provided on the first mixing pipe 701; a second mixing pipe 801 is provided between the first liquid inlet 203 of the first group 700 and the first liquid outlet 204 of the second group 800, and the second valve 802 is provided on the second mixing pipe 801.

[0065] In one embodiment of the present application, step S105 further includes: keeping the first valve 702 and the second valve 802 closed. After closing the valves, the water migration of the flow battery can be measured. If the valves are not closed, the water migration may mix through the first mixing pipe 701 and the second mixing pipe 801, resulting in inaccurate water migration measurement. During the detection process, when |V 10 -V 11 | / V1×100%≥5.0%, open the first valve 702 and the second valve 802. At this time, the positive and negative electrolytes are in a mixed liquid state. When the electrolyte valence and electrolyte volume on both sides of the positive and negative electrodes return to the initial liquid level, close the first valve 702 and the second valve 802 of the positive and negative electrodes.

[0066] The following is a test data with specific examples.

[0067] Electrode thickness specification 2.5mm, active area 48cm 2 , compression ratio 25%; proton exchange membrane thickness 50μm; total vanadium concentration of positive and negative electrolytes 1.70±0.1mol / L. Battery charging range 1.00-1.55V, respectively at 80, 150, 200, 300mA / cm 2 The liquid flow battery 100 is charged and discharged at a constant current, and the constant current charge and discharge cycle is repeated 10 times at each current density.

[0068] Test 1:

[0069] The diameter of the observation tube 303 is 4.2 mm and the measuring range is 20 mL. Through the second end 305 of the observation tube 303, first slowly fill the second cavity 300 with 40 mL of electrolyte. Turn on and adjust the rotation speed of the first pump 402 and the second pump 502 to 50 rpm, so that the reading of the volume flow meter is stable at 80 mL / min and the reading of the pressure gauge is stable at 0.15 bar. When the electrolyte fills the pipeline and flows continuously back to the first cavity 200, turn off the first pump 402 and the second pump 502, and inject the electrolyte into the second cavity 300 again through the second end 305 of the observation tube 303 until the liquid level of the electrolyte is at 1 / 2 of the observation tube 303. The volume of the electrolyte transferred to the positive and negative electrode cavities is 100 mL. At this time, the liquid level readings of the positive and negative electrode observation tubes 303 are both 10 mL. Restart the first pump 402 and the second pump 502. Adjust the speed of the stirring device 202 in the first chamber 200 to 20 rpm. Introduce nitrogen into the first chamber 200 at a volume flow rate of 0.2 L / min. The pressure gauge above the separator bottle reads close to 1 atmosphere. After connecting the charging and discharging equipment, perform a charge and discharge test on the flow battery 100.

[0070] Record the current density at 80, 150, 200, and 300 mA / cm 2 The electrolyte in the lower positive and negative electrode observation tube 303 reaches the scale value, and the calculated value is 150mA / cm 2 When measuring the water migration under the condition of 2 After the end of the liquid level reading, calculate 200, 300mA / cm 2 The water migration under the same conditions is deduced and the results are shown in Table 1.

[0071] Table 1 Water migration under various current densities in Test 1

[0072]

[0073] Test 2:

[0074] The diameter of the observation tube 303 is 4.2 mm and the measuring range is 20 mL. Through the second end 305 of the observation tube 303, first slowly fill the second cavity 300 with 40 mL of electrolyte. Turn on and adjust the rotation speed of the first pump 402 and the second pump 502 to 90 rpm so that the volume flow meter reading is stable at 150 mL / min and the pressure gauge reading is stable at 0.40 bar. When the electrolyte fills the pipeline and flows continuously back to the first cavity 200, turn off the first pump 402 and the second pump 502, and inject the electrolyte into the second cavity 300 again through the second end 305 of the observation tube 303 until the liquid level of the electrolyte is at 1 / 2 of the observation tube 303. The volume of the electrolyte transferred to the positive and negative electrode cavities is 100 mL. At this time, the liquid level readings of the positive and negative electrode observation tubes 303 are both 10 mL. Restart the first pump 402 and the second pump 502. Adjust the speed of the stirring device 202 in the first chamber 200 to 20 rpm. Introduce nitrogen into the first chamber 200 at a volume flow rate of 0.2 L / min. The pressure gauge above the separator bottle reads close to 1 atmosphere. After connecting the charging and discharging equipment, perform a charge and discharge test on the flow battery 100.

[0075] Record current densities of 80, 150, 200, and 300 mA / cm 2 The electrolyte in the lower positive and negative electrode observation tube 303 reaches the scale value, and the calculated value is 150mA / cm 2 When measuring the water migration under the condition of 2 After the end of the liquid level reading, calculate 200, 300mA / cm 2 The water migration under the same conditions is deduced and the results are shown in Table 2.

[0076] Table 2 Water migration under various current densities in Test 2

[0077]

[0078] The detection device of this application utilizes a separation unit to separate gases from the electrolyte, preventing them from affecting subsequent measurements. The measurement unit is simple to operate, allowing for easy addition of electrolyte and intuitive observation of water migration through an observation tube. This detection device offers a flexible design, simple operation, and a low risk of error. The device can be adapted to actual operating conditions by adjusting the specifications and structure of the flow battery and the electrolyte flow rate, enabling real-time, dynamic, and intuitive detection of water migration during different charge and discharge phases.

[0079] For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or more in different places in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics of one or more embodiments of the present application may be appropriately combined.

[0080] Similarly, it should be noted that, in order to simplify the description of the present disclosure and thus facilitate understanding of one or more embodiments, the foregoing descriptions of the embodiments of the present disclosure sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of the present disclosure requires more features than those mentioned. In fact, the features of an embodiment may be fewer than all the features of the individual embodiments disclosed above.

[0081] Although the present application has been described with reference to the current specific embodiments, ordinary technicians in this technical field should recognize that the above embodiments are only used to illustrate the present application, and various equivalent changes or substitutions can be made without departing from the spirit of the present application. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present application, they will fall within the scope of the present application.

Claims

1. A device for detecting water migration in a flow battery, characterized in that: include: reaction unit, separation unit and measurement unit, wherein, The reaction unit includes a flow battery having an electrolyte inlet and an electrolyte outlet; The separation unit has a first cavity, which is provided with a first liquid inlet, a first liquid outlet, a first gas inlet, and a second gas outlet. The first liquid inlet is connected to the electrolyte outlet. The first gas inlet is used to pass a purge gas into the first cavity, and the second gas outlet is used to discharge the gas in the first cavity. The measuring unit has a second cavity and an observation tube, the second cavity is provided with a second liquid inlet and a second liquid outlet, the second liquid inlet is connected to the first liquid outlet, and the second liquid outlet is connected to the electrolyte inlet, the observation tube has a first end and a second end, the first end is connected to the second cavity, and the second end is connected to the atmospheric environment.

2. The detection device according to claim 1, wherein The second liquid outlet and the electrolyte inlet are connected through a first pipe, and a first flow meter is provided on the first pipe; the first liquid outlet and the second liquid inlet are connected through a second pipe, and a second flow meter is provided on the second pipe.

3. The detection device according to claim 2, wherein: A first pump is also provided on the first pipeline, and the first pump is used to drive the electrolyte to flow from the second liquid outlet to the electrolyte inlet; a second pump is also provided on the second pipeline, and the second pump is used to drive the electrolyte to flow from the first liquid outlet to the second liquid inlet.

4. The detection device according to claim 1, wherein The first liquid inlet is connected to the electrolyte outlet via a third pipe, and a first pressure gauge is provided on the third pipe.

5. The detection device according to claim 1, wherein The first cavity is provided with a second pressure gauge, and the second pressure gauge is used to measure the pressure inside the first cavity.

6. The detection device according to claim 1, wherein A stirring device is provided in the first cavity, and the stirring device is used to stir the electrolyte in the first cavity to allow gas in the electrolyte to escape.

7. The detection device according to claim 1, wherein The observation tube is a transparent straight tube and is provided with a scale.

8. The detection device according to claim 1, wherein The reaction unit further includes a charging and discharging device, which is connected to the liquid flow battery and is used to control the charging and discharging of the liquid flow battery.

9. The detection device according to claim 1, wherein: The liquid flow battery has a positive electrode and a negative electrode, the electrolyte inlet includes a first electrolyte inlet and a second electrolyte inlet, and the electrolyte outlet includes a first electrolyte outlet and a second electrolyte outlet, wherein the first electrolyte inlet and the first electrolyte outlet are arranged at the positive electrode, and the second electrolyte inlet and the second electrolyte outlet are arranged at the negative electrode; wherein the first group of the separation unit and the measuring unit are arranged at the negative electrode, and the second group of the separation unit and the measuring unit are arranged at the positive electrode.

10. The detection device according to claim 9, wherein: A first mixing pipe is provided between the first liquid outlet of the first group and the first liquid inlet of the second group, and a first valve is provided on the first mixing pipe; a second mixing pipe is provided between the first liquid inlet of the first group and the first liquid outlet of the second group, and a second valve is provided on the second mixing pipe.

11. The detection device according to claim 1, wherein The observation tube has a first volume, the second cavity has a second volume, and the first volume accounts for 10% to 20% of the second volume.

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