Modularized electric pile structure and flow battery

Abstract

The invention belongs to the technical field of flow battery energy storage, and particularly relates to a modularized electric pile structure and a flow battery, the modularized electric pile structure comprises a plurality of electric pile units which are arranged in a stacking mode, and the electric pile units are sequentially arranged in the stacking direction; each electric pile unit comprises a plurality of stacked single batteries, a first end plate and a second end plate, the single batteries are sequentially arranged along the stacking direction, the first end plate and the second end plate are respectively and tightly pressed on two sides of the stacked single batteries, the first end plate is provided with a first inflow port and a first outflow port, and the second end plate is provided with a second inflow port and a second outflow port. The second end plate is provided with a second inflow port and a second outflow port, and the first end plate and the second end plate are provided with a fluid short-circuit port and a circuit short-circuit port. According to the modular electric pile structure disclosed by the invention, through modular design, rapid short circuit, isolation and replacement of a circuit and a flow path of a local fault unit of the flow battery are realized, continuous operation of a system is guaranteed, and maintenance efficiency and operation reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of flow battery energy storage technology, specifically to a modular stack structure and a flow battery. Background Technology

[0002] As a novel energy storage technology, flow batteries offer significant advantages in smoothing renewable energy output and ensuring stable power supply to the grid, thanks to their high efficiency, safety, reliability, and long cycle life. Unlike traditional rechargeable batteries, flow batteries store electrical energy in a flowing electrolyte, achieving energy storage and release through the redox reaction of active materials. This reaction process does not involve phase change, thus resulting in a longer lifespan.

[0003] Existing flow battery stacks mostly adopt a series-connected multi-cell stacking structure for assembly. In actual operation, when a single reactive cell in a series-connected multi-cell stack experiences performance degradation or flow failure, the entire stack often needs to be disassembled for repair or replacement. This results in long maintenance cycles, complex operations, and the overall performance is easily affected by changes in the matching state of individual cells during disassembly and assembly. Consequently, the operational reliability and maintenance efficiency of the flow battery system are reduced, limiting its widespread application in large-scale energy storage.

[0004] Therefore, it is necessary to provide a new modular fuel cell stack structure. Summary of the Invention

[0005] In view of this, the present invention provides a modular battery stack structure that connects battery cells in parallel to form battery modules, and then connects the battery modules in series. This not only increases the output current and eliminates bypass current to reduce losses and extend lifespan, but also achieves total voltage superposition, thereby improving the overall power of the battery stack and the system adaptability.

[0006] The technical solution adopted by the present invention to solve its technical problem is as follows: a modular fuel cell stack structure is provided, including: a plurality of stacked fuel cell units arranged sequentially along the stacking direction; each fuel cell unit includes a plurality of stacked single cells, a first end plate and a second end plate, the single cells arranged sequentially along the stacking direction, the first end plate and the second end plate respectively pressing against both sides of the plurality of stacked single cells, the first end plate having a first inflow port and a first outflow port, the second end plate having a second inflow port and a second outflow port, and the first end plate and the second end plate having a fluid short-circuit port and a circuit short-circuit port.

[0007] Furthermore, the modular fuel cell stack structure also includes a first cover plate and a second cover plate, which are respectively pressed against both sides of the multiple stacked fuel cell stack units. The first cover plate is provided with a total inflow port and a total outflow port.

[0008] Furthermore, there are two total inflow ports and two total outflow ports. The total inflow ports receive positive electrolyte and negative electrolyte respectively, and the total outflow ports receive positive electrolyte and negative electrolyte respectively.

[0009] Furthermore, there are two of each of the first inflow port, the first outflow port, the second inflow port, and the second outflow port, which respectively allow the positive electrolyte and the negative electrolyte to flow in or out. The first inflow port and the second inflow port are on the same axis, and the first outflow port and the second outflow port are on the same axis.

[0010] Furthermore, each of the first inflow port, the first outflow port, the second inflow port, and the fourth outflow port is equipped with a shut-off valve. The shut-off valve is a screw-on flow path shut-off valve. When the shut-off valve is screwed inward, the flow path in the corresponding first inflow port, the first outflow port, the second inflow port, and the fourth outflow port is shut off.

[0011] Furthermore, the fluid short-circuit port is provided with a first bypass port and a second bypass port on the first end plate, and a third bypass port and a fourth bypass port on the second end plate.

[0012] Furthermore, the first bypass port, the second bypass port, the third bypass port, and the fourth bypass port are each provided in twos, to introduce or lead out the positive electrode electrolyte and the negative electrode electrolyte, respectively.

[0013] Furthermore, the battery stack unit also includes multiple fastening bolts, which are sequentially passed through the first end plate, the multiple stacked single cells, and the second end plate for fixation.

[0014] Furthermore, when the fuel cell unit fails, shorting pipes are used to connect the first bypass port on the first end plate and the third bypass port on the second end plate, and the second bypass port on the first end plate and the fourth bypass port on the second end plate, respectively; shorting wires are used to connect the circuit shorting ports on the first end plate and the second end plate of the faulty fuel cell unit.

[0015] The present invention also provides a flow battery comprising the modular stack structure described in any of the preceding claims.

[0016] The beneficial effects of this invention are as follows: The modular stack structure of this invention encapsulates several individual cells into independent stack units. When a stack unit fails, rapid isolation can be achieved by short-circuiting its flow path and circuit, ensuring continuous operation of the battery system and significantly improving the resilience and operational robustness of the flow battery. The modular stack unit has flow path and circuit short-circuit ports at both ends, which, together with short-circuit pipes and short-circuit wires, allow for electrical and fluid isolation of the faulty stack unit without shutting down the system. During maintenance, the faulty stack unit can be directly replaced without disassembling the entire stack structure, avoiding damage caused by disassembly. The problem of mismatch between individual cells is significantly reduced, maintenance time is shortened, and repair efficiency is improved. The modular stack unit is stacked and fixed through the first end plate, the second end plate, the first cover plate, and the second cover plate. The overall structure has good rigidity and strong sealing, which facilitates connection with external pipeline systems. It is suitable for flow battery systems of different sizes and types, and has good engineering applicability and scalability. Furthermore, through partial maintenance and replacement of modular stack units, the overall downtime loss caused by single cell failure is reduced, the overall service life of the battery system is extended, the total life cycle operation and maintenance cost is reduced, and the economy and sustainability of the energy storage system are improved. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a normal flow path diagram of the modular fuel cell stack structure according to Embodiment 1 of the present invention;

[0019] Figure 2 This is a normal flow path diagram of the fuel cell stack unit in Embodiment 1 of the present invention; Figure 3 This is a circuit short-circuit state diagram of the modular fuel cell stack structure according to Embodiment 1 of the present invention; Figure 4 This is a circuit short-circuit state diagram of the fuel cell unit in Embodiment 1 of the present invention; Figure 5 This is a flow path short-circuit state diagram of the modular fuel cell stack structure according to Embodiment 1 of the present invention; Figure 6 This is a normal flow path diagram of the fuel cell stack unit in Embodiment 1 of the present invention; Figure 7 This is a flow path short-circuit state diagram of the fuel cell unit in Embodiment 1 of the present invention; The component names and their numbers in the diagram are as follows: Modular fuel cell stack structure 100; The battery stack unit 1, single cell 11, first end plate 12, first inflow port 121, first outflow port 122, first bypass port 123, second bypass port 124, second end plate 13, second inflow port 131, second outflow port 132, third bypass port 133, fourth bypass port 134, fastening bolt 14. First cover plate 2, total inflow port 21, total outflow port 22; Second cover plate 3; shut-off valve 4; short-circuit pipe 5; short-circuit wire 6. Detailed Implementation

[0020] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0021] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention 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. Therefore, they should not be construed as limitations on the present invention.

[0024] Throughout this specification, reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in some embodiments," or "in some of these embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0025] Example 1 like Figure 1 , Figure 2 As shown, this embodiment provides a modular fuel cell stack structure 100, including multiple stacked fuel cell units 1, a first cover plate 2, and a second cover plate 3. The fuel cell units 1 are arranged sequentially along the stacking direction. The first cover plate 2 and the second cover plate 3 are respectively pressed against both sides of the multiple stacked fuel cell units 1 to form a complete modular fuel cell stack. The fuel cell unit 1 serves as the basic power generation and energy storage module of the flow battery; the first cover plate 2 and the second cover plate 3 provide overall structural support, integrate external pipelines, and protect the internal fuel cell units 1 from external damage. The modular design of the fuel cell unit 1 facilitates unitized assembly, disassembly, and maintenance, and the first cover plate 2 and the second cover plate 3 enhance overall rigidity, facilitating system integration and external connections.

[0026] In some embodiments, each fuel cell stack 1 includes a plurality of stacked individual cells 11, a first end plate 12, and a second end plate 13. The individual cells 11 are arranged sequentially along the stacking direction, and the first end plate 12 and the second end plate 13 are respectively pressed against both sides of the plurality of stacked individual cells 11. The individual cells 11 are used to generate electrical energy through the redox reaction of the flow battery electrolyte. The first end plate 12 and the second end plate 13 are used to modularly divide the plurality of stacked individual cells 11, while realizing flow path allocation and short-circuiting function in the event of a failure of the fuel cell stack 1.

[0027] As an example, multiple fuel cell stack units 1 are stacked sequentially along the axial direction, with the first end plate 12 of adjacent fuel cell stack units 1 completely attached to the end face of the second end plate 13 of another fuel cell stack unit 1; the first cover plate 2 is attached to the outside of the first end plate 12 of the uppermost fuel cell stack unit 1, and the second cover plate 3 is attached to the outside of the second end plate 13 of the lowermost fuel cell stack unit 1, with the fuel cell stack unit 1, the first cover plate 2, and the second cover plate 3 coaxially aligned; or, the first cover plate 2 is attached to the outside of the first end plate 12 of the leftmost fuel cell stack unit 1, and the second cover plate 3 is attached to the outside of the second end plate 13 of the rightmost fuel cell stack unit 1, with the fuel cell stack unit 1, the first cover plate 2, and the second cover plate 3 coaxially aligned.

[0028] In some embodiments, the stack unit 1 includes 15 to 25 individual cells 11 stacked axially. Each individual cell 11 (not shown) includes a proton exchange membrane (PEM), an anode carbon felt, a cathode carbon felt, an anode electrode frame, a cathode electrode frame, an anode bipolar plate, and a cathode bipolar plate symmetrically arranged on both sides of the PEM. The PEM is located in the center, with the carbon felt, electrode frame, and bipolar plate arranged sequentially on either side. The PEM is thin-film and only allows protons to pass through, ensuring that protons can migrate from one electrode to another during charging / discharging, maintaining charge balance. The PEM is located between the anode and cathode carbon felts, separating the electrolytes at the anode and cathode to prevent mixing and contamination, ensuring continuous battery reaction. The anode carbon felt is located inside the anode electrode frame and closely adheres to the anode side of the PEM. The anode carbon felt has a porous structure, which increases the reaction contact area, improves the utilization rate of active materials, and enhances reaction efficiency. The cathode carbon felt is located inside the cathode electrode frame and closely adheres to the cathode side of the proton exchange membrane. Its porous structure increases the reaction contact area, improves the utilization rate of active materials, and enhances reaction efficiency. The anode electrode frame, roughly frame-shaped, is positioned at the edge of the anode carbon felt to fix it and prevent displacement, while also forming a sealed space to prevent electrolyte leakage. The anode bipolar plate has internal flow channels for electrolyte circulation. Located on the outermost side of the anode in the battery cell and adjacent to the anode electrode frame, its internal flow structure guides the electrolyte to flow evenly across the anode carbon felt, ensuring a complete reaction and improving the battery cell's reaction efficiency. The cathode bipolar plate has a flow field channel inside for the flow of electrolyte. The cathode bipolar plate is located on the outermost side of the cathode of the battery cell and is adjacent to the cathode electrode frame. The flow field structure inside the cathode bipolar plate is used to guide the electrolyte to flow evenly through the cathode carbon felt, ensuring a full reaction and improving the reaction efficiency of the battery cell.

[0029] In some embodiments, adjacent single cells 11 are connected in series by circuit wires.

[0030] In some embodiments, the first cover plate 2 has a total inflow port 21 and a total outflow port 22. There are two total inflow ports 21 and two total outflow ports 22. The total inflow port 21 is used for the positive electrolyte and the negative electrolyte to flow in respectively, and the total outflow port 22 is used for the positive electrolyte and the negative electrolyte to flow out respectively.

[0031] In some embodiments, the first end plate 12 has a first inflow port 121 and a first outflow port 122, and the second end plate 13 has a second inflow port 131 and a second outflow port 132. Two of each of the first inflow port 121, the first outflow port 122, the second inflow port 131, and the second outflow port 132 are provided for the flow of positive and negative electrolytes, respectively. The first inflow port 121 and the second inflow port 131 are on the same axis, and the first outflow port 122 and the second outflow port 132 are also on the same axis.

[0032] In some of these embodiments, such as Figure 1 , Figure 2 As shown, the electrolyte is output from the external storage tank via a pumping system, first enters the total inflow port 21 of the first cover plate 2 of the modular fuel cell stack structure 100, flows through each fuel cell stack unit 1 in sequence, and then returns from each fuel cell stack unit 1 in sequence, returning to the storage tank from the total outflow port 22 of the first cover plate 2, completing the cycle.

[0033] Specifically, the electrolyte inflow process is as follows: the electrolyte is connected from the external storage tank to the main inflow port 21 on the first cover plate 2 through a pipeline, and first flows through the first stack unit 1. The electrolyte flows from the main inflow port 21 to the first stack unit 1 closest to the first cover plate 2, and enters the stack unit 1 through the first inflow port 121 on the first end plate 12 of the stack unit 1. Then it flows in parallel through the flow field channels opened in the anode bipolar plates or cathode bipolar plates of all the stacked single cells 11 in the stack unit 1. When flowing through each single cell 11, the active material in the electrolyte undergoes a redox reaction on both sides of the proton exchange membrane to realize the charging or discharging process. A portion of the electrolyte continues to flow forward in parallel, exiting through the second inflow port 131 on the second end plate 13 of the stack unit 1; the electrolyte exiting the previous stack unit 1 continues to enter the first inflow port 121 on the first end plate 12 of the next adjacent stack unit 1; entering the interior of the stack unit 1, it then flows in parallel through the flow field channels opened in the anode bipolar plates or cathode bipolar plates of all the stacked single cells 11 within the stack unit 1; as it flows through each single cell 11, the active substances in the electrolyte undergo redox reactions on both sides of the proton exchange membrane, realizing the charging or discharging process; repeating the above process of flowing through the stack unit 1, the electrolyte flows through all stack units 1, and completes the same parallel distribution and electrochemical reaction within each stack unit 1.

[0034] The electrolyte outflow process is as follows: the electrolyte after the redox reaction in the single cell 11 flows out through the outlet of the flow field channel opened in the anode bipolar plate or cathode bipolar plate; the electrolyte after the redox reaction in all the single cells 11 in the corresponding stack unit 1 flows out through the first outflow port 122 on the first end plate 12. The electrolyte flowing out of the stack unit 1 located near the second cover plate 3 flows into the second outflow port 132 on the second end plate 13 of the adjacent stack unit 1 through the first outflow port 122 on the corresponding first end plate 12, and then flows out sequentially into the stack unit 1 near the first cover plate 2, and finally flows out through the first outflow port 122 on the first end plate 12 near the first cover plate 2 to the total outflow port 22 on the first cover plate 2.

[0035] In some of these embodiments, such as Figure 6 , Figure 7 As shown, a shut-off valve 4 is provided in the first inflow port 121, the first outflow port 122, the second inflow port 131, and the fourth outflow port 132. The shut-off valve 4 is used to cut off the flow of electrolyte. The shut-off valve 4 is a screw-on flow path shut-off valve. When the shut-off valve 4 is screwed inward, it can cut off the flow path in the corresponding first inflow port 121, first outflow port 122, second inflow port 131, and fourth outflow port 132.

[0036] In some of these embodiments, such as Figure 4 , Figure 7 As shown, the first end plate 12 and the second end plate 13 are provided with fluid short-circuit ports and circuit short-circuit ports (not shown in the figure). Specifically, the fluid short-circuit ports are a first bypass port 123 and a second bypass port 124 on the first end plate 12, and a third bypass port 133 and a fourth bypass port 134 on the second end plate 13. Two of each of the following ports are provided: one for introducing the positive electrolyte and one for leading out the negative electrolyte.

[0037] In some embodiments, the fuel cell stack unit 1 further includes multiple fastening bolts 14, which are used to sequentially pass through the first end plate 12, the multiple stacked single cells 11, and the second end plate 13 for fixation. The fastening bolts 14 are used to provide axial pressure, ensuring tight contact between the multiple single cells 11, preventing electrolyte leakage, maintaining good electrical contact, thereby enhancing the integrity and stability of the fuel cell stack unit 1 and facilitating modular assembly and disassembly.

[0038] like Figure 3-7As shown, when a certain fuel cell unit 1 in the modular fuel cell stack structure 100 fails, the first end plate 12 and the second end plate 13 at both ends of the corresponding fuel cell unit 1 are short-circuited to ensure that the modular fuel cell stack structure 100 continues to operate without shutting down. The specific steps for short-circuiting the electrolyte flow path are as follows: First, the location of the faulty fuel cell unit 1 is identified; then, the shut-off valves 4 inside the first inflow port 121, the first outflow port 122, the second inflow port 131, and the fourth outflow port 132 of the faulty fuel cell unit 1 are tightened inward to cut off the flow path inside the first inflow port 121, the first outflow port 122, the second inflow port 131, and the fourth outflow port 132, thereby cutting off the normal inflow and outflow path of the electrolyte into and out of the fuel cell unit 1; then, the external short-circuit pipes 5 are used to connect the valves 1 to the faulty fuel cell unit 1. Connect the first bypass port 123 on the first end plate 12 and the third bypass port 133 on the second end plate 13, and connect the second bypass port 124 on the first end plate 12 and the fourth bypass port 134 on the second end plate 13 to achieve electrolyte bypass flow. At this time, the electrolyte will no longer enter the interior of the faulty stack unit 1. After the electrolyte flows out from the previous stack unit 1 of the faulty stack unit 1, it directly bypasses the faulty stack unit 1 through the short pipe and flows into the next stack unit 1 of the faulty stack unit 1, thus achieving flow path bypass. The specific steps for shorting the circuit are as follows: First, confirm the position of the faulty fuel cell unit 1 in the circuit. Then, use the shorting wire 6 to connect the circuit shorting ports on the first end plate 12 and the second end plate 13 of the faulty fuel cell unit 1 (not shown in the figure). After the connection is completed, the current will flow out from the previous fuel cell unit 1 of the faulty fuel cell unit 1 and then directly flow through the shorting wire 6 to the next fuel cell unit 1 of the faulty fuel cell unit 1, bypassing the internal circuit of the faulty fuel cell unit 1. At this time, the faulty fuel cell unit 1 is electrically isolated and no longer participates in the charging and discharging of the modular fuel cell structure 100.

[0039] The modular stack structure 100 of this invention encapsulates several individual cells 11 into an independent stack unit 1. When a stack unit 1 fails, rapid isolation can be achieved by shorting its flow path and circuit, ensuring continuous operation of the battery system and significantly improving the resilience and operational robustness of the flow battery. The modular stack unit 1 has flow path and circuit shorting ports at both ends, which, together with shorting pipes 5 and shorting wires 6, enable electrical and fluid isolation of the faulty stack unit 1 without shutting down the system. During maintenance, the faulty stack unit 1 can be directly replaced without disassembling the entire stack structure, avoiding damage to individual cells caused by disassembly. The problem of mismatch status is solved, significantly shortening maintenance time and improving repair efficiency. The modular stack unit 1 is stacked and fixed through the first end plate 12, the second end plate 13, the first cover plate 2 and the second cover plate 3. The overall structure has good rigidity and strong sealing, which facilitates connection with external pipeline systems. It is suitable for flow battery systems of different sizes and types, and has good engineering applicability and scalability. Furthermore, by performing partial maintenance and replacing the modular stack unit 1, the overall downtime loss caused by single cell failure is reduced, the overall service life of the battery system is extended, the total life cycle operation and maintenance cost is reduced, and the economy and sustainability of the energy storage system are improved.

[0040] Example 2 Embodiments of the present invention also provide a flow battery, which includes the modular stack structure 100 provided in any of the above embodiments. Because the flow battery possesses all the technical features of the modular stack structure 100 provided in any of the above embodiments, it has the same technical effects as the modular stack structure 100 described above.

[0041] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of the present invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A modular fuel cell stack structure, characterized in that, include: Multiple stacked battery cells are arranged sequentially along the stacking direction. Each battery cell includes multiple stacked single cells, a first end plate, and a second end plate. The single cells are arranged sequentially along the stacking direction. The first end plate and the second end plate are respectively pressed against both sides of the multiple stacked single cells. The first end plate has a first inflow port and a first outflow port, and the second end plate has a second inflow port and a second outflow port. The first end plate and the second end plate are provided with fluid short-circuit ports and circuit short-circuit ports.

2. The modular fuel cell stack structure according to claim 1, characterized in that, The modular fuel cell stack structure also includes a first cover plate and a second cover plate, which are respectively pressed against both sides of the multiple stacked fuel cell stack units. The first cover plate has a total inflow port and a total outflow port.

3. The modular fuel cell stack structure according to claim 2, characterized in that, The system has two main inflow ports and two main outflow ports. The main inflow ports allow the positive electrolyte and negative electrolyte to flow into each other, and the main outflow ports allow the positive electrolyte and negative electrolyte to flow out.

4. The modular fuel cell stack structure according to claim 1, characterized in that, The first inflow port, the first outflow port, the second inflow port, and the second outflow port are each provided in twos, and each of them allows the positive electrode electrolyte and the negative electrode electrolyte to flow in or out respectively. The first inflow port and the second inflow port are on the same axis, and the first outflow port and the second outflow port are on the same axis.

5. The modular fuel cell stack structure according to claim 1, characterized in that, Each of the first inflow port, the first outflow port, the second inflow port, and the fourth outflow port is equipped with a shut-off valve. The shut-off valve is a screw-on flow path shut-off valve. When the shut-off valve is screwed inward, the flow path in the corresponding first inflow port, the first outflow port, the second inflow port, and the fourth outflow port is shut off.

6. The modular fuel cell stack structure according to claim 1, characterized in that, The fluid short-circuit port is provided with a first bypass port and a second bypass port on the first end plate, and a third bypass port and a fourth bypass port on the second end plate.

7. The modular fuel cell stack structure according to claim 6, characterized in that, The first bypass port, the second bypass port, the third bypass port and the fourth bypass port are each provided in twos, which respectively introduce or lead out the positive electrode electrolyte and the negative electrode electrolyte.

8. The modular fuel cell stack structure according to claim 1, characterized in that, The fuel cell stack unit also includes multiple fastening bolts, which are sequentially passed through the first end plate, the multiple stacked single cells, and the second end plate for fixation.

9. The modular fuel cell stack structure according to claim 6, characterized in that, When the fuel cell unit fails, shorting pipes are used to connect the first bypass port on the first end plate and the third bypass port on the second end plate, and the second bypass port on the first end plate and the fourth bypass port on the second end plate, respectively; shorting wires are used to connect the circuit shorting ports on the first end plate and the second end plate of the faulty fuel cell unit.

10. A flow battery, characterized in that, The flow battery includes the modular stack structure as described in any one of claims 1-9.

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