High-voltage flow battery stack and frequency modulation container type energy storage system

Abstract

The invention belongs to the field of flow battery energy storage, and particularly discloses a high-voltage flow battery electric pile and a frequency modulation type container type energy storage system. According to the application, the galvanic pile formed by connecting the large-active-area single batteries in series is divided into the modules formed by connecting the small-active-area single batteries in series, the multiple modules are electrically connected in series, and the liquid flow is connected in parallel to form the high-voltage flow battery galvanic pile, so that the voltage grade of the galvanic pile is improved and the current is reduced under the condition that the power of the galvanic pile is not changed; the high-voltage and low-current effect is achieved, the burden of power electronic equipment is reduced, the power electronic cost based on current parameter sensitivity factors is reduced, and the operation reliability and stability of an energy storage system can be improved by adopting the power electronic technology. In addition, the design of the high-voltage electric pile can provide more space for size optimization and volume power density improvement of the frequency modulation type container type energy storage system, and the application of the flow battery technology in high-demand scenes such as frequency modulation and the like is promoted.

Description

Technical Field

[0001] This application belongs to the field of flow battery energy storage, and more specifically, relates to a high-voltage flow battery stack and a frequency modulation type containerized energy storage system. Background Art

[0002] With the large-scale grid connection of intermittent and fluctuating renewable energy, the demand for flexible regulating power sources in the power grid has increased significantly. A flow battery consists of a stack unit, electrolytes, an electrolyte storage and supply unit, a management and control unit, etc. The mutual conversion between electrical energy and chemical energy is achieved through the reversible oxidation-reduction reaction (i.e., the reversible change of valence state) of the active substances in the positive and negative electrolyte solutions. During charging, the oxidation reaction occurs at the positive electrode to increase the valence state of the active substance, and the reduction reaction occurs at the negative electrode to lower the valence state of the active substance. The discharging process is the opposite. Different from general solid-state batteries, the positive and (or) negative electrolyte solutions of a flow battery are stored in external storage tanks and are transported to the inside of the battery through pumps and pipelines for reaction. Its main characteristics include the independence of the energy and power parts, long cycle life, environmental friendliness, and safety. Its energy storage capacity is determined by the volume of the electrolyte, while the power output is determined by the number of single cells in the stack, which enables the battery to flexibly adjust the capacity according to different requirements. As an electrochemical energy storage technology, flow battery energy storage has the characteristic of fast response speed compared with power sources with rotational inertia such as coal power, and has great potential in application scenarios such as power grid frequency modulation.

[0003] When the flow battery energy storage technology is used in the frequency modulation scenario, there are mainly problems of low reliability, high cost, and large floor area. Currently, large-capacity flow battery energy storage generally uses the inverters of lithium-ion batteries. The DC side voltage of megawatt-level inverters is mostly 1200V - 1500V, and even reaches 2000V. Taking the all-vanadium flow battery as an example, the voltage range is usually 1V to 1.6V. To meet the DC side voltage requirement of the inverter, about one thousand single cells need to be connected in series, which seriously affects the reliability. As the current density increases, that is, the battery current increases, the series reliability will affect the operation of larger-capacity energy storage systems more. At the same time, the large current increases the cost of power electronics with current sensitivity factors, restricts the freedom of the stack size used in the containerized energy storage system and the corresponding volume power density, and makes the unit power cost of a single set of liquid storage tanks, electrolyte delivery systems, sensors, and battery management systems relatively high. Using multiple inverter branches in parallel with high voltage and small current is an important means to solve high-reliability operation scenarios such as frequency modulation, and it is also the technical development trend to improve the power density of the containerized energy storage system and reduce the power cost. Summary of the Invention

[0004] Aiming at the defects of the prior art, the purpose of this application is to provide a high-voltage flow battery stack and a frequency-modulating containerized energy storage system, aiming to solve the problems of low voltage, large current, and leakage current risk in the existing flow battery stack.

[0005] The first aspect of this application relates to a high-voltage flow battery stack. The stack includes an upper end plate, a lower end plate, and 2 sub-stacks clamped between the two end plates. Each sub-stack includes n battery modules, and each battery module includes m single cells. The 2 sub-stacks are arranged along the stacking direction, and the n battery modules are arranged along the length direction and have no connection with each other. The m single cells in the battery module are connected in series. Between any two adjacent battery modules in the 2 sub-stacks, if module A and module B are a set of adjacent battery modules, module C and module D are another set of adjacent battery modules, and module A and C are stacked, module B and D are stacked, then module A and D are connected in series to form a series relationship of C-A-D-B. The liquid paths of the n battery modules in the sub-stack are connected in parallel. The liquid paths between the 2 sub-stacks are isolated.

[0006] Preferably, n satisfies the following relationship:

[0007] where is the expected value of the stack power, is the voltage of a single cell, is the current density of a single cell, is the effective current area of a single cell, is the number of single cells in each battery module.

[0008] Preferably, the value range of n is 2-8, and the value range of m is 25-50.

[0009] Preferably, the battery module further includes a current collector plate and an insulating plate along the stacking direction.

[0010] Preferably, the adjacent single cells in the battery module share a bipolar plate to achieve series connection.

[0011] Preferably, each battery module is equipped with 2 independent electrolyte inlets and 2 independent electrolyte outlets.

[0012] Preferably, the length of the flow battery stack matches the length, width, or height of the container body.

[0013] The second aspect of the present application relates to a high-voltage flow battery, which includes a plurality of flow battery stacks as described in the first aspect.

[0014] The third aspect of the present application relates to a frequency modulation type containerized energy storage system, which includes: a container body and a plurality of flow battery stacks as described in the first aspect; The plurality of flow battery stacks are neatly arranged in a matrix form inside the container body.

[0015] Preferably, the plurality of flow battery stacks are arranged horizontally or vertically and are connected in series or in parallel electrically.

[0016] It can be understood that the beneficial effects of the above second aspect to the third aspect can be referred to the relevant descriptions in the first aspect above, and will not be elaborated here.

[0017] Generally speaking, compared with the prior art by the above technical solutions conceived by the present application, the following beneficial effects are obtained: The present application proposes a high-voltage flow battery stack. The stack includes 2 sub-stacks, each sub-stack includes n battery modules, and each battery module includes m single cells; the 2 sub-stacks are arranged along the stacking direction, the n battery modules are arranged along the length direction and have no connection with each other; the m single cells in the battery module are connected in series; a series relationship of C-A-D-B is formed between any two adjacent battery modules in the 2 sub-stacks; the n battery modules in the sub-stack are connected in parallel in the liquid path; the liquid paths between the 2 sub-stacks are isolated. The present application divides a stack composed of a large active area single cell connected in series into modules composed of multiple small active area single cells connected in series. The multiple modules are connected in series electrically and in parallel in the liquid flow to form a high-voltage flow battery stack, so as to improve the voltage level of the stack, reduce the current, achieve the effect of high voltage and small current, reduce the burden on power electronic devices, reduce the power electronic cost based on current parameter sensitivity factors, and contribute to improving the operation reliability and stability of the energy storage system by using power electronic technology. In addition, the high-voltage stack design can also provide more space for the size optimization of the frequency modulation type containerized energy storage system and the improvement of the volume power density, and promote the application of flow battery technology in high-demand scenarios such as frequency modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a single cell provided by the present application.

[0019] Figure 2 is a schematic structural diagram of a sub-stack provided by the present application.

[0020] Figure 3 is a schematic structural diagram of a stack provided by the present application.

[0021] Figure 4 It is a schematic diagram of the circuit connection between two adjacent battery modules provided by this application.

[0022] Figure 5 It is a schematic diagram of the inlet and outlet of the electrolyte of the battery module provided by this application.

[0023] Figure 6 It is a schematic diagram of the complete structure of a high-voltage flow battery stack provided by this application.

[0024] Figure 7 It is a schematic diagram of the structure of a frequency modulation type containerized energy storage system provided by this application.

[0025] In all the drawings, the same reference numerals are used to represent the same components or structures, where: 1 is the bipolar plate on the positive electrode side, 2 is the flow frame on the positive electrode side, 3 is the electrode on the positive electrode side, 4 is the separator, 5 is the electrode on the negative electrode side, 6 is the flow frame on the negative electrode side, 7 is the bipolar plate on the negative electrode side, 8 is the end plate, 9 is the insulating plate, 10 is the current collecting plate, 11 is the single cell, 12, 13, 18, 19 are all electrolyte inlets, 14, 15, 16, 17 are all electrolyte outlets, 20, 21 are all sub-stacks, 22 is the fastening screw, 23 is the positive terminal port of the stack, 24 is the electrical series cable, and 25 is the negative terminal port of the stack. Detailed implementation manners

[0026] In order to make the objectives, technical solutions and advantages of this application clearer, the following further describes this application in detail with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0027] The following describes the embodiments of this application with reference to the drawings in the embodiments of this application.

[0028] In a first aspect, this application discloses a high-voltage flow battery stack, which includes an upper end plate, a lower end plate, and two sub-stacks sandwiched between the two end plates. Each sub-stack includes n battery modules, and each battery module includes m single cells.

[0029] The structure of the single cell is as Figure 1 shown. Compared with the "undivided" single cell, its components remain unchanged and it sequentially includes, along the stacking direction: the bipolar plate 1 on the positive electrode side, the flow frame 2 on the positive electrode side, the electrode 3 on the positive electrode side, the separator 4, the electrode 5 on the negative electrode side, the flow frame 6 on the negative electrode side, and the bipolar plate 7 on the negative electrode side. Among them, the flow frames 2 on the positive electrode side and 6 on the negative electrode side have the same structure, and the side with the flow channel faces the bipolar plate. However, in the dimension of length, the single cell in this application is 1 / n of the "undivided" single cell. Therefore, it has a smaller volume and a smaller current flowing through each single cell, which is 1 / n of the original.

[0030] The "flow battery" in this application includes, but is not limited to: all-vanadium flow battery, zinc-bromine flow battery, organic flow battery, iron-chromium flow battery.

[0031] As Figure 2 shown, the sub-stack includes n battery modules, and each battery module is stacked by m monomer cells 11, current collectors 10 and insulating plates 9 which are arranged closely and orderly. The n battery modules are arranged in sequence along the transverse direction. The whole stack includes 2 sub-stacks, with a total of 2n battery modules. The end plate 8 is located at the bottom layer.

[0032] The end plate is located on the outermost layer of the stack and is the support component of the whole structure. Its main function is to fasten all internal components by bolts to ensure the mechanical strength and sealing performance of the stack, and at the same time bear the pressure generated by the internal reaction. In addition, mounting holes are designed on the end plate for bolt fastening.

[0033] The insulating plate is closely attached to the inner side of the end plate, mainly used to isolate the electrical contact between the conductive components in the stack and the external environment, and avoid short-circuit phenomena during the operation of the stack. Its material usually has good voltage resistance and corrosion resistance to ensure the long-term stability of the system.

[0034] The current collector is located on the inner side of the insulating plate and is a key component for current transmission in the stack. Its function is to collect and guide the current of the battery module to the outside of the battery module. The current collector material usually uses metals with excellent high conductivity and corrosion resistance, such as copper or nickel, to reduce resistance and energy loss.

[0035] As Figure 3 shown, the stack includes an upper end plate, a lower end plate and 2 sub-stacks (20 and 21) clamped between the two end plates. The 2 sub-stacks are arranged along the stacking direction, and the n battery modules are arranged along the length direction and have no connection with each other; the m monomer cells in the battery module are connected in series. As Figure 4 shown, between any two adjacent battery modules in the 2 sub-stacks, if module A and module B are the same group of adjacent battery modules, module C and module D are another group of adjacent battery modules, and module A and C are stacked, module B and D are stacked, module A and D are connected in series to form a series relationship of C-A-D-B.

[0036] The n battery modules in the sub-stack are connected in parallel in the liquid path; the liquid paths between the 2 sub-stacks are isolated.

[0037] The monomer voltage expression formula of the all-vanadium flow battery:

[0038] Among them, is the standard electromotive force at single-cell balance; is the universal gas constant; is the battery temperature; is the number of equivalents transferred per mole of reduced or oxidized substance; is the Faraday constant; is the vanadium concentration of each valence state corresponding to the ionic concentration of the electrolyte in the single cell, and the valence state takes values of 2, 3, 4, and 5 respectively.

[0039] Because the battery monomers in the stack are in series, the stack current and the monomer current values are the same, and the expression is as follows:

[0040] Among them, is the stack current, is the monomer current, is the single-cell current density, is the effective current area of the single cell.

[0041] Also, because the current is restricted and needs to match the requirements of the power electronics devices behind the battery, with the improvement of battery technology, the single-cell current density can be made larger and larger. Therefore, it is necessary to reasonably adjust the effective current area of the single cell , and adjusting the effective current area of the single cell can be achieved by adjusting the number of modules in the sub-stack , that is:

[0042] Among them, is the expected value of the stack power, is the voltage of the monomer cell, is the single-cell current density, is the effective current area of the single cell, is the number of monomer cells in each battery module.

[0043] Preferably, the value range of n is 2 - 8, and the value range of m is 25 - 50.

[0044] Preferably, the adjacent monomer cells in the battery module share a bipolar plate to achieve series connection.

[0045] Preferably, as Figure 5 shown, each battery module is equipped with 2 independent electrolyte inlets and 2 electrolyte outlets. For two adjacent battery modules, the electrolyte inlets of one battery module are 12 and 13 respectively, and the electrolyte outlets are 14 and 15 respectively; the electrolyte inlets of the other battery module are 18 and 19 respectively, and the electrolyte outlets are 16 and 17 respectively.

[0046] Preferably, the length of the flow battery stack matches the length, width or height of the container body.

[0047] Example 1 This example is used to compare the performance of the flow battery stack proposed in this application with that of an undivided stack of the same volume.

[0048] The specific parameters of the stack in Experimental Group 1 (this application) are as follows: Length, width and height parameters of the stack: 1995 mm × 600 mm × 1162 mm; Number of battery modules n in the sub-stack: 4; Number of single cells m in the sub-stack module: 25; Important parameter values of the single cell include: ① Length, width and height: 600 mm × 495 mm × 32 mm; ② Active area parameters in the flow frame: 450 mm × 400 mm; ③ Current density: 250 mA / cm²; Rated current of the stack: 450 A; Rated voltage of the stack: 250 V; Rated power of the stack: 112.5 kW.

[0049] The specific parameters of the stack in Experimental Group 2 (this application) are as follows: Length, width and height parameters of the stack: 1995 mm × 600 mm × 1162 mm; Number of battery modules n in the sub-stack: 4; Number of single cells m in the sub-stack module: 50; Important parameter values of the single cell include: ① Length, width and height: 600 mm × 495 mm × 32 mm; ② Active area parameters in the flow frame: 450 mm × 400 mm; ③ Current density: 250 mA / cm²; Rated current of the stack: 450 A; Rated voltage of the stack: 500 V; Rated power of the stack: 225 kW.

[0050] Control Group 1: An undivided all-vanadium flow battery stack of the same volume Length, width and height parameters of the stack: 1990 mm × 600 mm × 1162 mm; Number of sub-stack modules: 1; Number of single cells m in the sub-stack module: 25; The important parameter values of a single cell include: ① Length, width and height: 600 mm × 1990 mm × 32 mm; ② Active area parameters in the flow frame: 450 mm × 1600 mm; ③ Current density: 250 mA / cm 2 ; Rated current of the stack: 1800 A; Rated voltage of the stack: 62.5 V; Rated power of the stack: 112.5 kW.

[0051] Comparison group 2: A vanadium redox flow battery stack of an undivided stack with the same volume Length, width and height parameters of the stack: 1990 mm × 600 mm × 1162 mm; Number of sub-stack modules: 1; Number of single cells m in the sub-stack module: 50; The important parameter values of a single cell include: ① Length, width and height: 600 mm × 1990 mm × 32 mm; ② Active area parameters in the flow frame: 450 mm × 1600 mm; ③ Current density: 250 mA / cm 2 ; Rated current of the stack: 1800 A; Rated voltage of the stack: 125 V; Rated power of the stack: 225 kW.

[0052] Comparing the experimental data of Example 1, it can be found that: (1) Compared with Experimental Group 1, Experimental Group 2 increased the number of series-connected single cells in the sub-stack from 25 to 50. It can be seen that the rated current of the stack remains unchanged, the rated voltage doubles, rising from 250 V to 500 V; and the rated power doubles, rising from 112.5 kW to 225 kW.

[0053] (2) Comparison group 1 uses a traditional undivided vanadium redox flow battery stack. Comparing Experimental Group 1 with Comparison group 1, it can be seen that under the same volume, for the stack proposed in this application, the rated power of the stack remains unchanged, the rated voltage becomes 4 times the original, rising from 62.5 V to 250 V, and the rated current becomes 1 / 4 of the original, dropping from 1800 A to 450 A.

[0054] (3) The control group 2 uses a traditional undivided all-vanadium redox flow battery stack. It can be seen that under the same volume, compared with the experimental group 1, when the number of series-connected monomers in the sub-stack is increased to 50, the rated voltage only increases to 125V, but the rated current is as high as 1800A, indicating that it is not feasible to achieve a high voltage effect by increasing the number of monomers; compared with the experimental group 2, the number of series-connected monomers in both is the same and the power is the same, but the rated voltage of the experimental group 2 can reach 500V, while that of the control group 2 is only 125V.

[0055] Example 2 With the development of the process, the current density is gradually increasing. In this example, the stacks under different current densities are compared.

[0056] The specific parameters of the stack in the experimental group 3 (this application) are as follows: The length, width and height parameters of the stack: 1995mm × 600mm × 1162mm; The number n of battery modules in the sub-stack: 8; The number m of single cells in the battery module: 25; The important parameter values of the single cell include: ① Length, width and height: 600mm × 247.5mm × 32mm; ② The parameters of the active area in the flow frame: 450mm × 200mm; ③ Current density: 500mA / cm²; Stack current: 450A; Stack voltage: 500V; Stack power: 225kW.

[0057] Taking the experimental group 1 in Example 1 as the control group and comparing it with the experimental group 3 in Example 2, it can be found that: with the increase of the current density, when the experimental group 3 keeps the stack current unchanged, more modules can be arranged in the same stack volume, thereby increasing the rated output voltage and rated power of the stack. The rated voltage reaches 500V and the rated power reaches 225kW.

[0058] Preferably, as Figure 6As shown, the flow battery stack also includes: a plurality of fastening bolts 22 and a plurality of electrical series cables 24. The various components of the flow battery stack can be fastened by bolts, and the n battery modules are kept without any connection with each other. The fastening rod runs through the entire stack structure, which is used to firmly press all components and maintain the overall sealing and stability of the stack. It is evenly distributed around the stack and fixed by nuts, providing the necessary mechanical support for the stack to prevent loosening or leakage caused by internal thermal expansion or external vibration. Any two groups of adjacent battery modules in the two sub-stacks form a series relationship through the electrical series cable 24. The stack positive electrode port 23 and the stack negative electrode port 25 of the flow battery stack are diagonally distributed, which are used to draw out the positive and negative currents of the stack, connect to the external circuit, and complete the power output of the entire battery system. They are made of corrosion-resistant and highly conductive metal materials to ensure the reliability of long-term operation.

[0059] Based on the above, in a second aspect, the present application discloses a high voltage liquid flow battery, comprising a plurality of liquid flow battery stacks as described in the first aspect.

[0060] Thirdly, Figure 7 As shown, the present application discloses a frequency-modulated container-type energy storage system, comprising: a container body and a plurality of liquid flow battery stacks as described in the first aspect; the plurality of liquid flow battery stacks are neatly arranged in a matrix form inside the container body. Preferably, the plurality of liquid flow battery stacks are arranged horizontally or vertically, and are electrically connected in series or in parallel. The shell of the standard container provides protection and support for the stack, while facilitating transportation and installation. The interior of the container is reasonably designed to make full use of the space to achieve a higher power density, while ensuring the efficient operation of the liquid flow, circuit and heat dissipation system.

[0061] As can be seen from the container schematic, the flow battery stack structure proposed in this application can improve modularity and flexibility, easy maintenance, effective thermal management, maximized space utilization, scalability, high reliability and cost-effectiveness. The modular design improves the flexibility of the system and facilitates expansion and maintenance. At the same time, the grid layout in the container helps to evenly distribute heat, and the cooling system can more effectively manage the heat generated during battery operation. In addition, the grid layout in the container can maximize the use of limited space and increase the power density of the stack. The use of standard container sizes can simplify the transportation and installation process and ensure the compatibility and interchangeability of the system. Modular production may reduce the cost of a single module, and mass production further reduces the overall cost. For a 20-foot container, the existing stack power is about 500 kW-750kW. This application can increase the stack power to 1200 kW-1500kW.

[0062] It should be understood that expressions such as "including" and "may include" that can be used in this application indicate the existence of the disclosed functions, operations, or components, and do not limit one or more additional functions, operations, and components. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, component, component, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, components, components, or a combination thereof.

[0063] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0064] In the description of the embodiments of this application, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that they are connected to each other and the relative positional relationship after connection remains unchanged. "Rotational connection" means that they are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that they are connected to each other and can slide relative to each other after connection. The orientation terms mentioned in the embodiments of this application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only references to the directions of the drawings. Therefore, the orientation terms used are for better and clearer description and understanding of the embodiments of this application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the embodiments of this application.

[0065] In addition, in the embodiments of this application, mathematical concepts such as symmetry, equality, parallelism, and perpendicularity are mentioned. These limitations are all in view of the current technological level, rather than absolute strict definitions in the mathematical sense. A small deviation is allowed, and approximate symmetry, approximate equality, approximate parallelism, approximate perpendicularity, etc. are all acceptable. For example, A is parallel to B means that A is parallel to B or approximately parallel to B, and the included angle between A and B can be between 0 degrees and 10 degrees. A is perpendicular to B means that A is perpendicular to B or approximately perpendicular to B, and the included angle between A and B can be between 80 degrees and 100 degrees.

[0066] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A high voltage liquid flow battery stack, characterized in that: The battery stack includes an upper end plate, a lower end plate and two sub-battery stacks sandwiched between the two end plates, each sub-battery stack includes n battery modules, and each battery module includes m single cells; The two sub-stacks are arranged along a stacking direction, and the n battery modules are arranged along a length direction without any connection to each other; The m single cells in the battery module are connected in series; Between any two groups of adjacent battery modules in the two sub-stacks, if module A and module B are the same group of adjacent battery modules, module C and module D are another group of adjacent battery modules, and modules A and C are stacked, and modules B and D are stacked, module A and module D are connected in series to form a series relationship of CADB; The n battery modules in the sub-stack are connected in parallel by liquid circuits; The liquid paths between the two sub-stacks are isolated.

2. The flow battery stack according to claim 1, characterized in that: n satisfies the following relationship: in, is the expected value of the stack power, is the single cell voltage, is the current density of the single cell, is the effective current area of ​​the single cell, The number of single cells in each battery module.

3. The flow battery stack according to claim 2, characterized in that: The value range of n is 2-8, and the value range of m is 25-50.

4. The flow battery stack according to claim 1, characterized in that: The battery module further includes a current collecting plate and an insulating plate along a stacking direction.

5. The flow battery stack according to claim 1, characterized in that: Adjacent single cells in the battery module share a bipolar plate to achieve series connection.

6. The flow battery stack according to claim 1, characterized in that: Each battery module is equipped with two independent electrolyte inlets and two electrolyte outlets.

7. The flow battery stack according to claim 1, characterized in that: The length of the liquid flow battery stack matches the length, width or height of the container body.

8. A high voltage liquid flow battery, characterized in that: It comprises a plurality of liquid flow battery stacks as claimed in any one of claims 1 to 7.

9. A frequency-modulated containerized energy storage system, characterized in that: include: A container body and a plurality of flow battery stacks according to any one of claims 1 to 7; Multiple flow battery stacks are neatly arranged in a matrix form inside the container.

10. The energy storage system according to claim 9, characterized in that: The multiple liquid flow battery stacks are arranged horizontally or vertically and electrically connected in series or in parallel.

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