Liquid storage device and flow battery

Abstract

The application relates to a liquid storage device and a flow battery, comprising: a liquid storage tank; a piston arranged in the liquid storage tank to divide a cavity in the liquid storage tank into a first cavity and a second cavity which are not communicated with each other; a liquid outlet main pipe and two liquid outlet branch pipes connected with the liquid outlet main pipe, the two liquid outlet branch pipes are respectively communicated with the first cavity and the second cavity, and a first electric valve is arranged on each liquid outlet branch pipe; a liquid return main pipe and two liquid return branch pipes connected with the liquid return main pipe, the two liquid return branch pipes are respectively communicated with the first cavity and the second cavity, and a second electric valve is arranged on each liquid return branch pipe; a circulating pump with adjustable pump speed is arranged on the liquid outlet main pipe; the piston is sealingly and slidably connected with the cavity wall of the liquid storage tank, the two first electric valves and the two second electric valves are controllably opened and closed so that one of the first cavity and the second cavity is a liquid outlet cavity and the other is a liquid return cavity, and the piston can move in the liquid storage tank under the action of a pressure difference between the liquid return cavity and the liquid outlet cavity.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, specifically to a liquid storage device and a flow battery. Background Technology

[0002] Flow batteries are an electrochemical energy storage technology. Their core feature is the mutual conversion of electrical energy and chemical energy through the "cyclic reaction of liquid electrolyte". They have advantages such as high safety, long life and adaptability to long-term energy storage, and have become one of the key technologies to support large-scale energy consumption and build new power systems.

[0003] When a flow battery is working, the positive and negative electrolytes stored in the positive and negative electrode reservoirs are transported to the stack by a circulating pump. Under the isolation of the ion exchange membrane, electrochemical reactions occur on the electrode surfaces to store and release energy. The total capacity of the flow battery is determined by the concentration of the active material in the electrolyte and the electrolyte volume. In the initial stage of charging and discharging, the concentration of active material participating in the electrochemical reaction is high, and the requirement for electrolyte flow rate is not high. In the later stage of charging and discharging, the concentration of active material decreases, and in order to maintain the electrochemical reaction rate, the electrolyte needs to maintain a higher flow rate to increase the electrolyte volume.

[0004] In traditional technologies, during the charging and discharging process of flow batteries, the electrolyte that has participated in the electrochemical reaction in the stack flows back to the storage tank and mixes with the original electrolyte. As a result, the concentration of active substances participating in the electrochemical reaction in the electrolyte in the storage tank gradually decreases. In order to maintain the electrochemical reaction rate, it is necessary to monitor the concentration of active substances participating in the electrochemical reaction in real time, and the pumping speed of the circulation pump needs to be changed in real time according to the real-time monitoring concentration. This makes the control system complex, difficult to implement, and costly. Utility Model Content

[0005] Therefore, it is necessary to provide a liquid storage device and a flow battery that can improve the above-mentioned problems.

[0006] A liquid storage device for a flow battery, comprising:

[0007] Storage tank;

[0008] A piston is disposed in the liquid storage tank to divide its internal cavities into a first cavity and a second cavity that are not interconnected.

[0009] The main outlet pipe and two branch outlet pipes connected to the main outlet pipe are respectively connected to the first cavity and the second cavity. Each branch outlet pipe is equipped with a first electric valve.

[0010] The system includes a main return pipe and two branch return pipes connected to the main return pipe. The two branch return pipes are respectively connected to the first cavity and the second cavity. Each branch return pipe is equipped with a second electric valve.

[0011] An adjustable-speed circulating pump is installed on the main outlet pipe;

[0012] The piston is sealed and slidably connected to the cavity wall of the liquid storage tank. The two first electric valves and the two second electric valves can be opened and closed in a controllable manner, such that when one of the first cavity and the second cavity is the liquid outlet cavity, the other is the liquid return cavity. The piston can move in the liquid storage tank under the action of the pressure difference in the liquid return cavity and the liquid outlet cavity.

[0013] In one embodiment, the piston includes a plate and a sealing ring, the sealing ring being disposed at the edge of the plate, and the piston being sealed and slidably connected to the cavity wall of the liquid storage tank through the sealing ring.

[0014] In one embodiment, the liquid storage device further includes a permanent magnet plate mounted on the piston;

[0015] In the first direction in which the piston moves in the liquid storage tank, a first magnetic sensor and a second magnetic sensor are respectively provided on the cavity walls of the first cavity and the second cavity away from each other;

[0016] When the first cavity is the liquid outlet cavity, the first magnetic sensor can generate a sensing signal when the permanent magnet sheet is at a distance of a first preset distance along the first direction; when the second cavity is the liquid outlet cavity, the second magnetic sensor can generate a sensing signal when the permanent magnet sheet is at a distance of a second preset distance along the first direction.

[0017] In one embodiment, the liquid storage tank includes an inner tank and an outer tank, the outer tank being wrapped around the inner tank, and the cavity of the liquid storage tank being formed within the inner tank.

[0018] The strength of the outer shell is greater than the strength of the inner tank.

[0019] In one embodiment, both the inner tank and the outer shell are made of metal; or

[0020] The inner tank is made of plastic or composite material, and the outer shell is made of metal.

[0021] In one embodiment, the two outlet pipes are respectively connected to the bottom walls of the first cavity and the second cavity, and the two return pipes are respectively connected to the top walls of the first cavity and the second cavity.

[0022] In one embodiment, the liquid storage device further includes a detection mechanism for detecting a first concentration of active material in the electrolyte of the liquid outlet chamber;

[0023] The pump speed of the circulating pump is adjustable according to the first concentration.

[0024] In one embodiment, the detection mechanism is an ultraviolet (UV) meter.

[0025] In one embodiment, the detection mechanism is installed on the return manifold to detect a second concentration of active material in the electrolyte of the return manifold as the first concentration.

[0026] A flow battery includes a positive electrode liquid storage device, a negative electrode liquid storage device, and a stack, wherein at least one of the positive electrode liquid storage device and the negative electrode liquid storage device is the liquid storage device described above.

[0027] The liquid outlet manifold of the liquid storage device is connected to the liquid inlet pipe of the corresponding electrode of the fuel cell stack, and the liquid return manifold of the liquid storage device is connected to the liquid outlet pipe of the corresponding electrode of the fuel cell stack.

[0028] The aforementioned liquid storage device and flow battery, on the one hand, use a piston to divide the liquid storage chamber into two non-communicating chambers, the first and the second. When one of the first and the second chambers is used as the outlet chamber, the other is used as the return chamber. The first and the second chambers are set independently, which is equivalent to the outlet and return chambers being set independently. In this way, the electrolyte that has participated in the reaction will not mix with the electrolyte in the outlet chamber when it flows back to the return chamber. Before each switch between the outlet and return chambers, the concentration of active material in the electrolyte in the outlet chamber will not change in real time and will remain consistent. In order to maintain the electrochemical reaction rate throughout the charging and discharging process, the pump speed of the circulation pump can be adjusted in steps according to the concentration of active material in the electrolyte in the outlet chamber. The pump speed of the circulation pump does not need to be adjusted in real time, which will not cause complexity in the control system and reduce the difficulty and cost of implementation. On the other hand, the piston can slide in the liquid storage tank under the action of the pressure difference between the return chamber and the outlet chamber, without the need for an external power device to drive the piston to slide, which simplifies the structural design of the liquid storage device. Attached Figure Description

[0029] Figure 1 This is a structural diagram of a liquid storage device provided in an embodiment of this application;

[0030] Figure 2 for Figure 1 A structural diagram of a partial structure of the liquid storage device shown;

[0031] Figure 3 A flowchart of a flow battery electrolyte delivery control method provided in an embodiment of this application.

[0032] Explanation of reference numerals in the attached figures:

[0033] 100. Liquid storage device; 10. Liquid storage tank; 11. First chamber; 12. Second chamber; 13. Inner tank body; 14. Outer shell; 20. Piston; 21. Plate body; 22. Sealing ring; 30. Main outlet pipe; 40. Branch outlet pipe; 50. First electric valve; 60. Circulation pump; 70. Main return pipe; 80. Branch return pipe; 90. Second electric valve; 110. Permanent magnet sheet; 120. First magnetic sensor; 130. Second magnetic sensor; 140. Detection mechanism. Detailed Implementation

[0034] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0035] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0038] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0039] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0040] See Figure 1 and Figure 2 One embodiment of this application provides a liquid storage device 100 for use in a flow battery. The liquid storage device 100 can be used as a positive electrode liquid storage device or a negative electrode liquid storage device, and is not limited thereto.

[0041] The liquid storage device 100 includes a liquid storage tank 10 and a piston 20. The piston 20 is disposed in the cavity (liquid storage chamber) of the liquid storage tank 10 to divide the liquid storage chamber into a first chamber 11 and a second chamber 12 that are not interconnected. Both the first chamber 11 and the second chamber 12 are used to store electrolyte. The specific shape of the liquid storage tank 10 is not limited; for example, the outer contour of the liquid storage tank 10 can be cylindrical or rectangular.

[0042] Continue reading Figure 1The liquid storage device 100 also includes a main outlet pipe 30 and two branch outlet pipes 40. The two branch outlet pipes 40 are respectively connected to the first chamber 11 and the second chamber 12. Each branch outlet pipe 40 is equipped with a first electric valve 50. Both branch outlet pipes 40 are connected to the main outlet pipe 30. That is, the two branch outlet pipes 40 are connected to the liquid storage tank 10 and respectively to the first chamber 11 and the second chamber 12. The connection between the two branch outlet pipes 40 and the main outlet pipe 30 not only achieves mechanical connection but also enables communication between internal channels. The first electric valve 50 is used to control the on / off state of the corresponding branch outlet pipe 40. The liquid storage device 100 also includes a circulation pump 60, which is installed on the main outlet pipe 30 and has an adjustable pump speed. The main outlet pipe 30 is used to connect to the liquid inlet pipe of the flow battery stack. When the liquid storage device 100 is used as a positive electrode liquid storage device, the liquid outlet manifold 30 is connected to the positive electrode liquid inlet pipe of the fuel cell stack. When the liquid storage device 100 is used as a negative electrode liquid storage device, the liquid outlet manifold 30 is connected to the negative electrode liquid inlet pipe of the fuel cell stack.

[0043] Continue reading Figure 1 The liquid storage device 100 also includes a main return pipe 70 and two branch return pipes 80. The two branch return pipes 80 are respectively connected to the first chamber 11 and the second chamber 12. Each branch return pipe 80 is equipped with a second electric valve 90, and both branch return pipes 80 are connected to the main return pipe 70. That is, the two branch return pipes 80 are connected to the liquid storage tank 10 and respectively connected to the first chamber 11 and the second chamber 12. The connection between the two branch return pipes 80 and the main return pipe 70 not only achieves mechanical connection but also enables communication between internal channels. The second electric valve 90 is used to control the opening and closing of the corresponding branch return pipe 80. The main return pipe 70 is used to connect to the liquid outlet pipe of the flow battery stack. When the liquid storage device 100 is used as a positive electrode liquid storage device, the main return pipe 70 is connected to the positive electrode liquid outlet pipe of the stack; when the liquid storage device 100 is used as a negative electrode liquid storage device, the main return pipe 70 is connected to the negative electrode liquid outlet pipe of the stack.

[0044] Furthermore, the piston 20 is sealed and slidably connected to the wall of the liquid storage chamber. By controlling the opening and closing of the two first electric valves 50 and the two second electric valves 90, one of the first chamber 11 and the second chamber 12 can be used as the liquid outlet chamber and the other as the liquid return chamber. Specifically, when the first electric valve 50 corresponding to the first chamber 11 is open and the second electric valve 90 is closed, and the first electric valve 50 corresponding to the second chamber 12 is closed and the second electric valve 90 is open, the first chamber 11 serves as the liquid outlet chamber and the second chamber 12 serves as the liquid return chamber. When the first electric valve 50 corresponding to the first chamber 11 is closed and the second electric valve 90 is open, and the first electric valve 50 corresponding to the second chamber 12 is open and the second electric valve 90 is closed, the second chamber 12 serves as the liquid outlet chamber and the second chamber 12 serves as the liquid return chamber.

[0045] The electrolyte flowing out of the outlet chamber, powered by the circulating pump 60, flows through the outlet branch pipe 40 corresponding to the outlet chamber to the outlet main pipe 30, and then through the outlet main pipe 30 into the fuel cell stack to undergo an electrochemical reaction on the electrode surface. The reacted electrolyte flows through the return main pipe 70 to the return branch pipe 80 corresponding to the return chamber, and then through the return branch pipe 80 into the return chamber. The outflow pressure of the electrolyte in the outlet chamber decreases, while the inflow pressure of the electrolyte in the return chamber increases. This creates a pressure difference between the outlet and return chambers. The piston 20, sealed in the storage chamber, slides in the storage chamber under the action of this pressure difference, causing the volume of the outlet chamber to gradually decrease and the volume of the return chamber to gradually increase until all the electrolyte flows back into the return chamber. After the electrolyte has flowed back into the return chamber, the return chamber and the outlet chamber are switched by controlling the opening and closing of the two first electric valves 50 and the two second electric valves 90. That is, the original return chamber is switched to the outlet chamber, and the original outlet chamber is switched to the return chamber. After the return chamber and the outlet chamber have switched, the electrolyte begins the next cycle. In this way, the first chamber 11 and the second chamber 12 alternately serve as the outlet chamber and the return chamber, and the cycle repeats.

[0046] The liquid storage device 100 provided in this application embodiment has two aspects. First, the piston 20 divides the liquid storage chamber into a first chamber 11 and a second chamber 12 that are not interconnected. When one of the first chamber 11 and the second chamber 12 is used as the outlet chamber, the other is used as the return chamber. The first chamber 11 and the second chamber 12 are set independently, which is equivalent to the outlet chamber and the return chamber being set independently. In this way, the electrolyte that has participated in the reaction will not mix with the electrolyte in the outlet chamber when it flows back to the return chamber. Before each switch between the return chamber and the outlet chamber, the concentration of active material in the electrolyte in the outlet chamber will not change in real time and will always remain consistent. In order to maintain the electrochemical reaction rate throughout the charging and discharging process, the pumping speed of the circulation pump 60 can be adjusted stepwise according to the concentration of active material in the electrolyte in the outlet chamber. The pumping speed of the circulation pump 60 does not need to be adjusted in real time, which will not cause complexity in the control system and reduce the implementation difficulty and implementation cost. On the other hand, the piston 20 can slide in the liquid storage tank 10 under the action of the pressure difference between the return chamber and the outlet chamber. There is no need for an external power device to drive the piston 20 to slide, which simplifies the structural setting of the liquid storage device 100.

[0047] It is important to clarify that the active materials in the electrolyte of a flow battery refer to the core chemical substances that achieve energy storage and release through their own redox reactions (electron transfer) during the battery's charging and discharging process. Their concentration, stability, and reactivity directly determine the capacity, efficiency, and lifespan of the flow battery. For example, in a vanadium redox flow battery, the active materials in both the positive and negative electrode electrolytes are vanadium ions in different valence states. The concentration of active materials in the electrolyte refers to the "effective content" of the core chemical substances that can participate in energy storage and release through redox reactions per unit volume of electrolyte.

[0048] It should also be noted that in this application, the piston 20 can move within the storage chamber under the influence of pressure difference, resulting in a smaller outlet chamber and a larger return chamber. Compared to separating the storage chamber with a fixed partition, this avoids wasting space in the storage tank 10, minimizing the footprint while maintaining storage capacity. Furthermore, the outlet and return chambers are independent of each other. The electrolyte returning to the return chamber after the reaction will not mix with the electrolyte in the outlet chamber, preventing ion cross-contamination between the return and outlet electrolytes and thus improving electrolyte utilization.

[0049] In some embodiments, see further reference. Figure 1 and Figure 2 The storage tank 10 includes an inner tank 13 and an outer shell 14, with the outer shell 14 enclosing the inner tank 13 and a storage cavity formed within the inner tank 13. The outer shell 14 has a greater strength than the inner tank 13. By ensuring that the outer shell 14 has a greater strength than the inner tank 13, the outer shell 14 can limit the deformation of the inner tank 13, reducing the risk of electrolyte separation failure.

[0050] In some specific embodiments, both the inner tank 13 and the outer shell 14 are made of metal. The metal used for the inner tank 13 has high corrosion resistance, while the metal used for the outer shell 14 has high strength. Specifically, the outer shell 14 is made of stainless steel or ordinary steel with rust-proof treatment.

[0051] In other embodiments, the inner tank 13 is made of plastic or composite material, while the outer shell 14 is made of metal. For example, the inner tank 13 can be made of PVC plastic or modified polypropylene (PPH).

[0052] It should be noted that, since the electrolyte flows in the pipeline, the outlet branch pipe 40, the outlet main pipe 30, the return main pipe 70, and the return branch pipe 80 are also made of corrosion-resistant metal or hard plastic, such as PVC plastic. Furthermore, the first electric valve 50 and the second electric valve 90 can also be corrosion-resistant electric valves.

[0053] In some embodiments, two outlet pipes 40 are connected to the bottom walls of the first cavity 11 and the second cavity 12, respectively, and two return pipes 80 are connected to the top walls of the first cavity 11 and the second cavity 12, respectively. Since the two return pipes 80 are connected to the top walls of the first cavity 11 and the second cavity 12, it facilitates the discharge of gas from the return pipes 80 when liquid is poured into the first cavity 11 or the second cavity 12. Furthermore, since the two outlet pipes 40 are connected to the bottom walls of the first cavity 11 and the second cavity 12, it facilitates the emptying of the electrolyte in the outlet cavity when the first cavity 11 or the second cavity 12 is used as an outlet cavity.

[0054] It is conceivable that in some other embodiments, the liquid outlet pipe 40 or the liquid return pipe 80 may also be connected to other parts of the cavity wall of the first cavity 11 and the second cavity 12, or to the side wall of the first cavity 11 and the second cavity 12, which is not limited here.

[0055] In some embodiments, see further reference. Figure 2 The piston 20 includes a plate 21 and a sealing ring 22. The sealing ring 22 is located on the outer edge of the plate 21. The piston 20 is sealed and slidably connected to the cavity wall of the liquid storage tank 10 through the sealing ring 22. The sealing ring 22 can ensure the sealing with the cavity wall of the liquid storage tank 10, and does not restrict the sliding of the piston 20 relative to the cavity wall of the liquid storage tank 10.

[0056] Alternatively, the sealing ring 22 may be made of corrosion-resistant rubber, such as PTFE rubber.

[0057] In some embodiments, see further reference. Figure 1 The liquid storage device 100 also includes a permanent magnet plate 110, which is mounted on the piston 20. Specifically, the permanent magnet plate 110 is embedded in the plate 21 of the piston 20, or attached to the surface of the plate 21 and treated with anti-corrosion treatment (e.g., surface coating), preferably a neodymium permanent magnet plate 110. In the first direction in which the piston 20 moves in the liquid storage tank 10, a first magnetic sensor 120 and a second magnetic sensor 130 are respectively provided on the cavity walls of the first cavity 11 and the second cavity 12 away from each other. When the first cavity 11 is the liquid outlet cavity, the first magnetic sensor 120 can generate a sensing signal when the permanent magnet plate 110 moves along the first direction to a distance of a first preset distance. When the second cavity 12 is the liquid outlet cavity, the second magnetic sensor 130 can generate a sensing signal when the permanent magnet plate 110 moves along the first direction to a distance of a second preset distance.

[0058] When the first magnetic sensor 120 or the second magnetic sensor 130 senses the permanent magnet 110, it indicates that the piston 20 is close to or in close contact with the wall of the liquid outlet chamber. This indicates that the electrolyte in the liquid outlet chamber has been drained. Thus, the first electric valve 50 and the second electric valve 90 can be controlled in a timely manner based on whether the first magnetic sensor 120 or the second magnetic sensor 130 sends a signal, thereby controlling the switching between the return chamber and the liquid outlet chamber and improving working efficiency.

[0059] In some embodiments, see further reference. Figure 1 The liquid storage device 100 also includes a detection mechanism 140, which is used to detect the first concentration of active material in the electrolyte of the liquid chamber. The pumping speed of the circulation pump 60 is adjustable according to the first concentration. The detection mechanism 140 can detect the first concentration in a timely manner, and the pumping speed of the circulation pump 60 can be adjusted according to the first concentration, which can further improve working efficiency.

[0060] Optionally, the testing institution 140 is an ultraviolet (UV) tester, usually referring to a UV-Vis spectrophotometer. The core principle of the UV tester in detecting the concentration of active substances in the electrolyte is the Lambert-Beer Law - when monochromatic light passes through a solution containing the substance to be tested, the degree of light absorption is proportional to the concentration of the substance in the solution and the optical path length.

[0061] Furthermore, the detection mechanism 140 is installed on the return main pipe 70 to detect the second concentration of the active material in the electrolyte of the return main pipe 70 as the first concentration. The detection mechanism 140 detects the second concentration of the active material in the electrolyte of the return main pipe 70 after the nth cycle in the fuel cell stack, and uses this second concentration as the first concentration of the active material in the electrolyte to be used in the (n+1)th cycle. Thus, the first concentration corresponding to the liquid outlet chamber at the (n+1)th liquid outlet can be obtained at the nth return cycle. Since the electrolyte flowing in the return main pipe 70 is the same electrolyte as at the nth return cycle, i.e., the same electrolyte as at the (n+1)th liquid outlet, installing the detection mechanism 140 on the return main pipe 70 ensures the accuracy of the detection.

[0062] It is conceivable that in other implementations, the type of detection mechanism 140 is not limited, as long as it can detect the concentration of active substances in the electrolyte. Furthermore, the installation location of the detection mechanism 140 is not limited. For example, the detection mechanism 140 can be directly installed in the first chamber 11 and the second chamber 12. In this case, the detection mechanism 140 can directly detect the concentration of active substances in the electrolyte of the liquid chamber, further ensuring the accuracy of the detection. Alternatively, the detection mechanism 140 can also be installed on the outlet manifold 30, which can also detect the first concentration; this is not limited in this respect.

[0063] Another embodiment of this application provides a flow battery, including a positive electrode storage device, a negative electrode storage device, and a fuel cell stack, wherein at least one of the positive electrode storage device and the negative electrode storage device is the aforementioned storage device 100. The outlet manifold 30 of the storage device 100 is connected to the inlet pipe of the corresponding electrode of the fuel cell stack, and the return manifold 70 of the storage device 100 is connected to the outlet pipe of the corresponding electrode of the fuel cell stack. Since the aforementioned storage device 100 has beneficial effects, the flow battery including the aforementioned storage device 100 has the same beneficial effects, which will not be described in detail here.

[0064] See Figure 3 Another embodiment of this application provides a method for controlling the delivery of electrolyte in a flow battery, comprising:

[0065] S110: The first chamber 11 and the second chamber 12 of the liquid storage tank 10 are controlled to have one of the chambers containing electrolyte as the outlet chamber and the other as the return chamber;

[0066] When electrolyte is poured into the storage tank 10, it is poured into one of the first chamber 11 and the second chamber 12. That is, only one of the first chamber 11 and the second chamber 12 contains electrolyte, while the other is empty. When electrolyte is poured into the first chamber 11, it serves as the outlet chamber, and the second chamber 12 is empty; when electrolyte is poured into the second chamber 12, it serves as the outlet chamber, and the first chamber 11 is empty.

[0067] In some specific embodiments, the liquid storage device 100 has a main outlet pipe 30 and two branch outlet pipes 40 connected to the main outlet pipe 30. The two branch outlet pipes 40 are respectively connected to the first chamber 11 and the second chamber 12. Each branch outlet pipe 40 is equipped with a first electric valve 50. The liquid storage device 100 also has a main return pipe 70 and two branch return pipes 80 connected to the main return pipe 70. The two branch return pipes 80 are respectively connected to the first chamber 11 and the second chamber 12. Each branch return pipe 80 is equipped with a second electric valve 90. A circulation pump 60 is located on the main outlet pipe 30. When electrolyte is injected into the first chamber 11, the first electric valve 50 corresponding to the first chamber 11 is opened, the first electric valve 50 corresponding to the second chamber 12 is closed, both second electric valves 90 are opened, the circulation pump 60 rotates in the reverse direction, the electrolyte enters the first chamber 11, and air flows from the two branch return pipes 80 to the main return pipe 70 and is discharged to the outside. When electrolyte is injected into the second chamber 12, the first electric valve 50 corresponding to the second chamber 12 is opened, the first electric valve 50 corresponding to the first chamber 11 is closed, both second electric valves 90 are opened, the circulation pump 60 rotates in the opposite direction, the electrolyte enters the second chamber 12, and the air flows from the two return pipes 80 to the return main pipe 70 and is discharged to the outside.

[0068] After the electrolyte is injected, the outlet manifold 30 is connected to the inlet pipe of the fuel cell stack, and the return manifold 70 is connected to the outlet pipe of the fuel cell stack, forming a closed loop.

[0069] S120: Determine the target pump speed of the circulating pump 60 based on the first concentration of active material in the electrolyte in the outlet chamber and the target operating current of the flow battery.

[0070] It should be noted that the first concentration refers to the "effective content" of the target active material (the substance that will flow to the stack to participate in the electrochemical reaction) participating in the storage and release of electrical energy through redox reactions in a unit volume of electrolyte in the outlet chamber. The target active material varies depending on the type of flow battery, whether it is charging or discharging, and whether it is the positive or negative electrode. For example, when the flow battery is a vanadium redox flow battery, the target active material corresponding to the positive electrode during charging is VO₂. 2+ The target active material V corresponding to the negative electrode 3+ .

[0071] To ensure that the electrochemical reaction rate of the flow battery remains constant throughout the entire charge and discharge process, the flow battery needs to operate at a constant target operating current while maintaining a constant rated voltage and a constant stack. Maintaining a constant operating current (i.e., constant current operation) is one of the commonly used operating modes to ensure the achievement of the operating goals of "high efficiency, reliability, and long life".

[0072] Since the total capacity of a flow battery is determined by the concentration of the active material in the electrolyte and the electrolyte volume, the concentration of the active material participating in the electrochemical reaction decreases as the flow battery is charged and discharged. To ensure the electrochemical reaction rate throughout the entire charging and discharging process, the electrolyte volume needs to be increased as the active material concentration decreases. Once the first concentration is obtained, the target pump speed of the circulation pump 60 can be determined based on the first concentration and the target operating current. Since the target operating current is constant, a lower first concentration corresponds to a higher target pump speed for the circulation pump 60, and vice versa.

[0073] S130: Control the circulating pump 60 to pump the electrolyte in the outlet chamber to the fuel cell stack at the target pump speed, and the electrolyte that has participated in the electrochemical reaction in the fuel cell stack flows back to the return chamber;

[0074] After determining the target pump speed of the circulating pump 60, the circulating pump 60 rotates forward at the target pump speed to pump the electrolyte in the outlet chamber to the fuel cell stack. After participating in the electrochemical reaction in the fuel cell stack, the electrolyte flows back to the return chamber.

[0075] S140: When the electrolyte in the outlet chamber is detected to be emptied, control one of the first chamber 11 and the second chamber 12 that is a return chamber to switch to an outlet chamber, and control the other of the outlet chamber to switch to a return chamber, and return to execute steps S120 and S130.

[0076] When the electrolyte in the outlet chamber is detected to be empty, it proves that all the electrolyte has been discharged into the return chamber. At this time, the outlet chamber and the return chamber are interchanged. One of the first chamber 11 and the second chamber 12 that was originally the outlet chamber is switched to the return chamber, and the other that was originally the return chamber is switched to the outlet chamber. Steps S120 and S130 are then executed, and the electrolyte enters the stack for the next cycle.

[0077] In step S140, the outlet chamber and the return chamber are interchanged. The electrolyte stored in the returned chamber after the interchange is the electrolyte that participated in the electrochemical reaction in the fuel cell stack previously. When returning to step S120, the first concentration will no longer be the same as the previous first concentration. The target pump speed of the circulation pump 60 is determined based on the current first concentration and the target operating current of the flow battery. Subsequently, the circulation pump 60 is controlled to operate at the updated target pump speed. The above steps are repeated until charging and discharging are completed.

[0078] The electrolyte delivery control method for a flow battery provided in this application uses one of the independent first chamber 11 and second chamber 12 as the outlet chamber and the other as the return chamber. This ensures that the electrolyte returning to the return chamber after the reaction does not mix with the electrolyte in the outlet chamber. Before each switch between the return and outlet chambers, the concentration of the active material in the electrolyte in the outlet chamber remains constant, meaning the first concentration is constant before each switch. Since the first concentration is constant, the target pump speed of the circulation pump 60 is determined based on the first concentration and the target operating current. Therefore, the target pump speed remains constant before each switch between the return and outlet chambers, and the pump speed of the circulation pump 60 changes in a stepwise manner according to the different first concentrations. The pump speed of the circulation pump 60 does not need to be adjusted in real time, which avoids complicating the control system and reduces implementation difficulty and cost.

[0079] In some embodiments, step S110 includes:

[0080] The first electric valve 50 corresponding to one of the electrolytes in the first chamber 11 and the second chamber 12 is opened and the second electric valve 90 is closed to make it an outlet chamber. The second electric valve 90 on the return pipe 80 corresponding to the other chamber is opened and the first electric valve 50 is closed to make it a return chamber.

[0081] The first chamber 11 and the second chamber 12 are respectively connected to the main outlet pipe 30 through an outlet branch pipe 40. The main outlet pipe 30 supplies electrolyte from the outlet chambers to the fuel cell stack. The first chamber 11 and the second chamber 12 are respectively connected to the main return pipe 70 through a return branch pipe 80. The main return pipe 70 supplies electrolyte from the fuel cell stack back to the return chamber. A circulation pump 60 is installed on the main outlet pipe 30. A first electric valve 50 is installed on each outlet branch pipe 40, and a second electric valve 90 is installed on each return branch pipe 80.

[0082] With the above configuration, by controlling the opening and closing of the first electric valve 50 and the second electric valve 90, one of the first chamber 11 and the second chamber 12 can be used as the liquid outlet chamber and the other as the liquid return chamber, which is convenient for control.

[0083] In some embodiments, before step S120, the following steps are also included:

[0084] Obtain the first concentration of active material in the electrolyte in the outlet chamber.

[0085] The electrolyte that has been filled but has not yet entered the fuel cell stack to undergo an electrochemical reaction is defined as the initial electrolyte. The concentration of active materials in the initial electrolyte is generally a known value, denoted as the first preset value. The first concentration corresponding to the initial electrolyte after participating in the electrochemical reaction can be obtained by detection by the detection device 140. Of course, the first concentration corresponding to the initial electrolyte can also be obtained by detection, which is not limited here.

[0086] In some specific embodiments, obtaining the first concentration of the active substance in the electrolyte of the outlet chamber includes:

[0087] The first concentration is obtained by directly detecting the concentration of active substances in the electrolyte in the liquid chamber;

[0088] Optionally, a detection mechanism 140 is installed on the first cavity 11 and the second cavity 12, and the detection mechanism 140 detects the first concentration. The detection mechanism 140 can be an ultraviolet meter.

[0089] The first concentration is obtained by directly detecting the concentration of active substances in the electrolyte in the liquid chamber, so as to ensure the accuracy of obtaining the first concentration.

[0090] In other specific embodiments, obtaining the first concentration of the active substance in the electrolyte of the outlet chamber includes:

[0091] The second concentration of active material in the electrolyte in the return manifold 70 after the nth cycle in the fuel cell stack is obtained, and the second concentration is used as the first concentration of active material in the electrolyte that will participate in the (n+1)th cycle.

[0092] The initial electrolyte in the storage tank 10 enters the fuel cell stack reaction once, which is counted as one cycle in the fuel cell stack. The first chamber 11 and the second chamber 12 are respectively connected to the return liquid main pipe 70 through the return liquid branch pipe 80. The return liquid main pipe 70 supplies electrolyte in the fuel cell stack to return to the return liquid chamber. The first concentration of active material in the initial electrolyte is the first preset value.

[0093] In the above configuration, while the electrolyte is undergoing its nth cycle in the battery stack, the detection mechanism 140 detects the second concentration of the active material in the electrolyte in the return manifold 70. At this time, the electrolyte corresponding to the second concentration flows into the return chamber. During the (n+1)th cycle, the return chamber corresponding to the nth cycle switches to the outlet chamber, and the second concentration can be used as the first concentration of the outlet chamber. In this way, the first concentration corresponding to the next cycle can be obtained during the previous cycle, avoiding obtaining the first concentration after the cycle is completed, which can improve the working efficiency of the flow battery. Furthermore, the electrolyte flowing back to the return chamber from the return manifold 70 is the electrolyte that will participate in the electrochemical reaction next time, ensuring the accuracy of the detection.

[0094] Furthermore, the second concentration of the active material in the electrolyte in the return manifold 70 after the nth cycle in the fuel cell stack is obtained, and this second concentration is used as the first concentration of the active material in the electrolyte that will participate in the (n+1)th cycle, including:

[0095] The third concentration of active material in the electrolyte in the return manifold 70 after the nth cycle in the fuel cell stack is obtained at multiple time points with a first preset time interval between them.

[0096] The average concentration of multiple third concentrations is calculated as the second concentration, and this second concentration is used as the first concentration corresponding to the active substance in the electrolyte that will participate in the (n+1)th cycle. Different valence states of active substances (such as vanadium ions V...) 2+ V 3+ V 4+ V 5+ It has unique characteristic absorption spectra (such as V) 4+ There is a strong absorption peak at ~760 nm, V 3+ (It has a characteristic peak at ~590nm). When the testing institution is an ultraviolet tester, the ultraviolet tester detects the absorbance of the electrolyte at a specific wavelength. Combined with Lambert-Beer's law (absorbance is proportional to concentration), the concentration of the target active substance can be obtained, that is, the third concentration. The average concentration is obtained by fitting multiple third concentrations as the second concentration.

[0097] The above settings detect the third concentration at multiple time intervals and use the average of the multiple third concentrations as the second concentration to reduce detection errors and ensure precise control of the pump speed of the circulating pump 60.

[0098] It should be noted that the first preset duration can be selected as needed, such as setting the first preset duration to 10 minutes.

[0099] In some embodiments, the target pump flow rate is determined based on the first concentration, the number of individual cells in the fuel cell stack, the fuel cell stack current, and the regulation coefficient, and the target pump speed is determined based on the target pump flow rate.

[0100] Where Qt=kNI / (96500c), Qt is the target pump flow rate (unit L / min), k is the adjustment coefficient, N is the number of single cells in the stack, I is the target operating current (unit mA), c is the first concentration (unit mlo / L), and k≥1.

[0101] By setting Qt = kNI / (96500c), the electrolyte supply rate in the flow battery is matched to the electrochemical reaction requirements, avoiding performance degradation due to insufficient active material. Since the target pump speed and target pump flow rate are positively correlated, the target pump speed can be obtained based on the target pump flow rate.

[0102] Generally, once the target pump flow rate is determined, the circulating pump 60 can operate at the target pump speed corresponding to that model by inputting the target pump flow rate.

[0103] In some specific embodiments, the current density is set to 160 mA / cm², the number of individual cells is 50, and the effective reaction area of ​​each individual cell is 5000 cm². 2If k = 1, then Qt = 1 * 50 * 160 * 5000 / 96500c = 414.5 / cmL / s = 24.87 / cL / min. It can be seen that the smaller c is, the larger Qt is, and the higher the corresponding target pump speed. Specifically, the initial electrolyte concentration can be set to 1.5 mol / L, then when the electrolyte in the outlet chamber is the initial electrolyte, the corresponding Qt is 16.58 L / min.

[0104] In some embodiments, detecting the evacuation of electrolyte from the outlet chamber includes:

[0105] When the piston 20 in the storage tank 10 moves to a predetermined distance from the wall of the outlet chamber under the pressure difference of the electrolyte in the return chamber and the outlet chamber, the electrolyte in the outlet chamber is discharged.

[0106] With the above configuration, the piston 20 is sealed and slidably connected to the wall of the liquid storage chamber. The piston 20 can slide in the liquid storage tank 10 under the action of the pressure difference between the return liquid chamber and the outlet liquid chamber. No external power equipment is required to drive the piston 20 to slide, which simplifies the structural configuration of the liquid storage device 100.

[0107] Furthermore, when the piston 20 in the storage tank 10 moves to a predetermined distance from the wall of the outlet chamber under the pressure difference of the electrolyte in the return chamber and the outlet chamber, the electrolyte in the outlet chamber is emptied, including:

[0108] When the piston 20 moves into the outlet chamber, the magnetic sensor senses the permanent magnet plate 110 on the piston 20, and the electrolyte in the outlet chamber is drained.

[0109] In the first direction in which the piston 20 moves within the liquid storage tank 10, a first magnetic sensor 120 and a second magnetic sensor 130 are respectively provided on the walls of the first chamber 11 and the second chamber 12, respectively, away from each other. When the first chamber 11 is the liquid outlet chamber, the first magnetic sensor 120 can generate a sensing signal when the permanent magnet plate 110 moves along the first direction to a distance from its first preset distance. When the second chamber 12 is the liquid outlet chamber, the second sensor can generate a sensing signal when the permanent magnet plate 110 moves along the first direction to a distance from its second preset distance. When the first magnetic sensor 120 or the second magnetic sensor 130 senses the permanent magnet plate 110, it indicates that the piston 20 is close to or in close contact with the wall of the liquid outlet chamber, indicating that the electrolyte in the liquid outlet chamber has been drained. Thus, whether the liquid outlet chamber is drained can be determined based on whether the first magnetic sensor 120 or the second magnetic sensor 130 generates a signal, facilitating control.

[0110] In some embodiments, controlling one of the first chamber 11 and the second chamber 12, which serves as a return chamber, to switch to an outlet chamber, and switching the outlet chamber to a return chamber includes:

[0111] The first electric valve 50 corresponding to the return liquid chamber in the first chamber 11 and the second electric valve 90 is opened and closed, so that the return liquid chamber is switched to the outlet liquid chamber. The first electric valve 50 corresponding to the outlet liquid chamber is closed and the second electric valve 90 is opened, so that the outlet liquid chamber is switched to the return liquid chamber.

[0112] The above configuration allows for switching between the return chamber and the outlet chamber by controlling the opening and closing of the two first electric valves 50 and the two second electric valves 90. That is, the original return chamber is switched to the outlet chamber, and the original outlet chamber is switched to the return chamber, which facilitates control.

[0113] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A liquid storage device for a flow battery, characterized in that, include: Storage tank (10); A piston (20) is disposed in the liquid storage tank (10) to divide its internal cavities into a first cavity (11) and a second cavity (12) that are not connected to each other; The main outlet pipe (30) and two branch outlet pipes (40) connected to the main outlet pipe (30) are respectively connected to the first chamber (11) and the second chamber (12). Each branch outlet pipe (40) is equipped with a first electric valve (50). The return main pipe (70) and two return branch pipes (80) are connected to the return main pipe (70). The two return branch pipes (80) are respectively connected to the first chamber (11) and the second chamber (12). A second electric valve (90) is installed on each of the return branch pipes (80). An adjustable-speed circulating pump (60) is installed on the main outlet pipe (30); The piston (20) is sealed and slidably connected to the cavity wall of the liquid storage tank (10). The two first electric valves (50) and the two second electric valves (90) can be opened and closed in a controlled manner so that when one of the first cavity (11) and the second cavity (12) is the liquid outlet cavity, the other is the liquid return cavity. The piston (20) can move in the liquid storage tank (10) under the action of the pressure difference in the liquid return cavity and the liquid outlet cavity.

2. The liquid storage device according to claim 1, characterized in that, The piston (20) includes a plate (21) and a sealing ring (22). The sealing ring (22) is located on the edge of the plate (21). The piston (20) is sealed and slidably connected to the cavity wall of the liquid storage tank (10) through the sealing ring (22).

3. The liquid storage device according to claim 1, characterized in that, The liquid storage device also includes a permanent magnet plate (110), which is mounted on the piston (20); In the first direction in which the piston (20) moves in the liquid storage tank (10), a first magnetic sensor (120) and a second magnetic sensor (130) are respectively provided on the cavity walls of the first cavity (11) and the second cavity (12) away from each other; When the first cavity (11) is the liquid outlet cavity, the first magnetic sensor (120) can generate a sensing signal when the permanent magnet sheet (110) is at a distance of a first preset distance along the first direction; when the second cavity (12) is the liquid outlet cavity, the second magnetic sensor (130) can generate a sensing signal when the permanent magnet sheet (110) is at a distance of a second preset distance along the first direction.

4. The liquid storage device according to claim 1, characterized in that, The liquid storage tank (10) includes an inner tank body (13) and an outer shell body (14), the outer shell body (14) is wrapped around the inner tank body (13), and the cavity of the liquid storage tank (10) is formed in the inner tank body (13); The strength of the outer shell (14) is greater than the strength of the inner tank (13).

5. The liquid storage device according to claim 4, characterized in that, Both the inner tank (13) and the outer shell (14) are made of metal. or The inner tank (13) is made of plastic or composite material, and the outer shell (14) is made of metal.

6. The liquid storage device according to claim 1, characterized in that, The two outlet pipes (40) are respectively connected to the bottom walls of the first cavity (11) and the second cavity (12), and the two return pipes (80) are respectively connected to the top walls of the first cavity (11) and the second cavity (12).

7. The liquid storage device according to claim 1, characterized in that, The liquid storage device further includes a detection mechanism (140), which is used to detect the first concentration of active substances in the electrolyte of the liquid outlet chamber; The pumping speed of the circulating pump (60) is adjustable according to the first concentration.

8. The liquid storage device according to claim 7, characterized in that, The testing device (140) is an ultraviolet (UV) meter.

9. The liquid storage device according to claim 7, characterized in that, The detection mechanism (140) is installed on the return liquid main (70) and is used to detect the second concentration of active substances in the electrolyte of the return liquid main (70) as the first concentration.

10. A flow battery, characterized in that, It includes a positive electrode liquid storage device, a negative electrode liquid storage device, and a fuel cell stack, wherein at least one of the positive electrode liquid storage device and the negative electrode liquid storage device is a liquid storage device as described in any one of claims 1-9; The liquid outlet manifold (30) of the liquid storage device is connected to the liquid inlet pipe of the corresponding electrode of the fuel cell stack, and the liquid return manifold (70) of the liquid storage device is connected to the liquid outlet pipe of the corresponding electrode of the fuel cell stack.

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