Flow battery stack

Abstract

The invention belongs to the technical field of flow batteries, and particularly discloses a flow battery stack which is composed of end plates, current collectors and single batteries, and each single battery is of a laminated structure composed of a bipolar plate, a rubber plate, a runner plate frame, an ionic membrane and two electrodes; the rubber plate and the runner plate frame are tightly pressed under the acting force of the bipolar plate to form a closed and sealed electrolyte public runner; the same rubber plate is extruded at different positions to form a plurality of sealing structures, specifically, the rubber plate and a runner plate frame part are laminated to form a public runner, a liquid inlet runner seal and a liquid outlet runner seal; the rubber plate, the runner plate frame and the bipolar plate laminated structure form a bipolar plate seal; the laminated part of the rubber plate and the ionic membrane plate frame forms an ionic membrane seal; and the rubber plate and the runner plate frame are laminated to form a galvanic pile outer seal and an electrolyte common runner seal. According to the invention, stack sealing parts are integrated on one rubber plate, so that the use amount of sealing rings is greatly reduced, the liquid leakage risk of the stack is reduced, and the reliability of the stack is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flow batteries, and in particular to a flow battery stack. Background Art

[0002] Energy storage technology is an effective strategy to address issues such as the efficient utilization of renewable energy and environmental pollution. Among many current energy storage technologies, flow batteries have the characteristics of good safety and long service life, and are ideal batteries for long-term energy storage applications. In a flow battery, the stack is a core component, and the stability of its performance is directly related to the performance and cost of the entire system. A flow battery charges and discharges when electrolyte liquid circulates within the stack, causing the electrolyte to undergo redox electrochemical reactions at the positive and negative electrodes respectively, storing and releasing electrical energy in the electrolyte, and achieving the conversion of electrical energy and chemical energy. The electrolyte is divided into positive and negative electrolytes. When the stack is in use, on the one hand, it is necessary to ensure that the positive and negative electrolytes do not mix within the stack, and on the other hand, it is also necessary to ensure that the electrolyte does not leak outside the stack, which requires ensuring the long-term sealing performance of the stack.

[0003] Generally, the basic components of a stack include positive and negative electrode frames, bipolar plates, electrodes, and ion membranes. At the same time, a common channel and a current-limiting channel for the electrolyte are provided in the stack structure. To ensure the normal operation of the stack, the sealing performance between these components is very important, and multiple rubber sealing rings need to be set to ensure the sealing of the electrolyte. The installation of the sealing rings requires a large amount of manual labor. At the same time, since the bipolar plates used in the stack are graphite plates with a small temperature coefficient, and the electrode frames are usually plastics with a large temperature coefficient, this will cause the bipolar plates and the electrode frames to be prone to displacement and misalignment due to temperature changes during the use of the battery, resulting in a reduction in the reliability of the sealing structure formed by the sealing rings. At the same time, the cost of a large number of sealing rings is also relatively high. Moreover, each single cell requires one electrode frame for both the positive and negative electrodes, resulting in a large number of components and high costs. Summary of the Invention

[0004] Aiming at the technical deficiencies of the existing flow battery stack structure, the present invention provides a flow battery stack with a new structure. This new structure stack solves the problem of multiple seals in the flow battery stack through a rubber plate, and ensures the sealing stability of various materials under inconsistent thermal expansion coefficients, improves the reliability of long-term use of the stack, and at the same time reduces the usage of the stack electrode frames, which is beneficial to reducing the cost of the stack, thus solving the problems mentioned in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: A flow battery stack, the stack is composed of end plates, current collectors, and single cells. Among them, each single cell is a laminated structure composed of a bipolar plate, a rubber plate, a flow channel frame, an ion membrane, and two electrodes; Under the action of the bipolar plate, the rubber plate is pressed against the flow channel plate frame to form a closed and sealed common electrolyte flow channel. The same rubber plate is squeezed at different positions to form multiple sealing structures, specifically including: 1) The rubber plate and the flow channel plate frame are partially laminated to form a common flow channel and seals for the liquid inlet and outlet channels; 2) The laminated structure of the rubber plate, the flow channel plate frame, and the bipolar plate forms a bipolar plate seal; 3) The laminated part of the rubber plate and the ion membrane plate frame forms an ion membrane seal; 4) The rubber plate and the flow channel plate frame are laminated to form an outer seal of the stack and a seal for the common electrolyte flow channel.

[0006] Preferably, in the flow battery stack, two adjacent rubber plates and the flow channel plate frame located therebetween form 4 current-limiting flow channels, namely the positive electrolyte inlet flow channel, the positive electrolyte outlet flow channel, the negative electrolyte inlet flow channel, and the negative electrolyte outlet flow channel.

[0007] Preferably, there is only one flow channel plate frame in each single cell of the flow battery stack. The positive electrolyte inlet flow channel, the positive electrolyte outlet flow channel, the negative electrolyte inlet flow channel, and the negative electrolyte outlet flow channel are respectively arranged at 4 independent positions of the flow channel plate frame, and the flow channel depth is the entire thickness of the plate frame, that is, the 4 current-limiting flow channels penetrate the flow channel plate frame.

[0008] Preferably, the adjacent flow channel plate frames in the flow battery stack are partially stacked together on the outside to limit the position of each flow channel plate frame along the axial direction of the stack, ensuring the consistency of the compression amount at the sealing position formed by each rubber plate and constituting a stable sealing structure of the stack.

[0009] Preferably, in the flow battery stack, the positive electrolyte enters the common electrolyte flow channel of the stack from the storage tank through the pump, then reaches the flow channel outlet through the positive electrolyte inlet flow channel, and then enters the reaction electrode placed on the bipolar plate on one side of the ion membrane for the electrochemical reaction of charge and discharge. Then it enters the inlet of the positive electrolyte outlet channel from the other end of one side of the ion membrane and returns to the storage tank through the positive electrolyte outlet flow channel and the common channel; The negative electrolyte enters the common electrolyte flow channel of the stack from the storage tank through the pump, then reaches the channel outlet through the negative electrolyte inlet flow channel, and then enters the reaction electrode placed on the bipolar plate on the other side of the ion membrane for the electrochemical reaction of charge and discharge. Then it enters the inlet of the negative electrolyte outlet channel from the other end of the other side of the ion membrane and returns to the storage tank through the negative electrolyte outlet flow channel and the common channel; during this process, the positive and negative electrolytes do not mix with each other and do not leak.

[0010] Preferably, the material of the flow channel plate frame is one of polypropylene (PP), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), modified polyvinyl chloride (CPVC), polyvinyl chloride (PVC), polyoxymethylene (POM), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), or polysulfone (PSF).

[0011] Preferably, the thickness of the rubber plate is 0.4 - 5.0 mm, and the compression amount at the extrusion seal formed by the rubber plate ranges from 11% to 61%.

[0012] Preferably, the material of the rubber plate is one of ethylene propylene diene monomer rubber (EPDM), butyl rubber (IIR), nitrile butadiene rubber (NBR), soft rubber thermoplastic rubber (TPR), thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), and thermoplastic dynamically vulcanized elastomer (TPV).

[0013] Preferably, the flow battery is an iron-chromium flow battery, a vanadium redox flow battery, a vanadium-iron flow battery, or an organic flow battery.

[0014] The beneficial effects of the present invention are as follows: The flow battery stack structure provided by the present invention concentrates the stack sealing components on a rubber plate, greatly reducing the usage amount of sealing rings, reducing the risk of liquid leakage in the stack, improving the reliability of the stack. At the same time, the through-flow channel structure on the flow channel plate frame is beneficial to fabricating a thinner single cell of the flow battery. In addition, the design of this stack structure reduces the installation process, significantly improves the stack assembly efficiency, and greatly reduces the operating labor intensity of the assembly personnel, thereby reducing the cost of the stack from the aspects of materials and manufacturing. Description of the Drawings

[0015] Figure 1 Schematic diagram of the external shape of the flow battery stack in Embodiment 1 of the present invention; Figure 2 Schematic diagram of the single cell structure of the flow battery stack in Embodiment 1 of the present invention; Figure 3 Schematic diagram of the partial sealing structure of the flow battery stack in Embodiment 1 of the present invention; Figure 4 Schematic diagram of the electrolyte flowing in the flow channel plate frame in Embodiment 1 of the present invention; Figure 5 Schematic diagram of the rubber plate structure in Embodiment 1 of the present invention; In the figure, 1 - end plate; 2 - current collector; 3 - single cell; 4 - bipolar plate; 5 - electrode; 6 - rubber plate; 7 - ion membrane; 8 - flow channel plate frame; 9 - common electrolyte flow channel; 10 - positive electrolyte inlet flow channel; 11 - negative electrolyte inlet flow channel; 12 - positive electrolyte outlet flow channel; 13 - negative electrolyte outlet flow channel. Detailed Embodiments

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. It should be noted that: similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0018] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, 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 should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0019] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0020] Embodiment 1 The present invention provides a technical solution: a flow battery stack, as Figure 1 shown, the stack is composed of an end plate 1, a current collector 2 and single cells 3. Among them, as Figure 2 shown, each single cell 3 is a laminated structure composed of a bipolar plate 4, a rubber plate 6, a flow channel plate frame 8, an ion membrane 7 and two electrodes 5; As Figure 3 shown, the rubber plate 6 is pressed against the flow channel plate frame 8 under the action of the bipolar plate 4 to form a closed and sealed common electrolyte flow channel 9.

[0021] Furthermore, the upper part of this common electrolyte flow channel is a graphite bipolar plate, and the lower part is a rigid plastic flow channel plate frame and is connected to the rubber plates on the side (left and right sides) (with liquid channels opened on the right side of the rubber plate to facilitate the flow of the electrolyte to the right), forming a reliably sealed liquid flow collection area.

[0022] Since both the bipolar plate and the plastic flow channel plate frame are made of thin rigid plastic materials, warping is likely to occur during injection molding, affecting the sealing effect. In the present invention, the number of plate frames of a single cell is changed from 2 to 1, increasing the thickness of the plate frame to reduce warping. At the same time, the compressible rubber plate in the middle layer during sealing can reduce or absorb the influence of warping of the bipolar plate or the flow channel plate frame on the sealing, improving the sealing performance of the flow battery stack.

[0023] The same rubber plate is squeezed at different positions to form multiple sealing structures, specifically including: 1) The rubber plate and the flow channel plate frame are partially laminated to form a common flow channel and seals for the inlet and outlet liquid flow channels; 2) The laminated structure of the rubber plate, the flow channel plate frame, and the bipolar plate forms a bipolar plate seal; 3) The laminated part of the rubber plate and the ion membrane plate frame forms an ion membrane seal; 4) The rubber plate and the flow channel plate frame are laminated to form an outer seal of the stack and a seal for the common electrolyte flow channel. This new structure stack solves the problem of multiple seals of the flow battery stack with one rubber plate, and ensures the sealing stability of various materials with inconsistent coefficients of thermal expansion, improving the reliability of the stack during long-term use. At the same time, the usage of the stack plate frame is reduced, which is beneficial to reducing the cost of the stack.

[0024] Further, two adjacent rubber plates 6 in the flow battery stack and the flow channel plate frame 8 located therebetween form 4 current-limiting flow channels, namely the positive electrolyte inlet flow channel 10, the positive electrolyte outlet flow channel 12, and the negative electrolyte inlet flow channel 11, the negative electrolyte outlet flow channel 13.

[0025] Further, each single cell of the flow battery stack has only one flow channel plate frame 8, as Figure 3 and Figure 4 shown, the positive electrolyte inlet flow channel 10, the positive electrolyte outlet flow channel 12, the negative electrolyte inlet flow channel 11, and the negative electrolyte outlet flow channel 13 are respectively arranged at 4 independent positions of the flow channel plate frame, and the flow channel depth is the entire thickness of the plate frame, that is, the 4 current-limiting flow channels penetrate the flow channel plate frame. Further, the positive and negative flow channels of the frame plate are longitudinally through structures. In the prior art, each single cell is composed of two plate frames, the positive flow channel is arranged on the positive plate frame, and the negative flow channel is arranged on the negative plate frame. In this way, the thickness of the flow channel is limited, and the flow channel width needs to be increased to increase the cross-sectional area of the flow channel to reduce the flow resistance of the flow channel, resulting in a large planar area of the single cell, which is not conducive to improving the power density of the stack and reducing the cost. The independent through-type plate frame flow channel of the present invention overcomes the above deficiencies and is conducive to making a thinner stack.

[0026] Further, the adjacent flow channel plate frames in the flow battery stack are partially laminated together on the outside to limit the position of each flow channel plate frame along the axial direction of the stack, ensuring the consistency of the compression amount at the sealing position formed by each rubber plate and forming a stable sealing structure of the stack.

[0027] Further, in the flow battery stack, the positive electrolyte enters the common flow channel 9 of the stack electrolyte from the storage tank through a pump, then reaches the flow channel outlet through the positive electrolyte inlet flow channel 10, and then enters the reaction electrode placed on the bipolar plate on one side of the ion membrane to carry out the electrochemical reaction of charge and discharge. Then, it enters the inlet of the positive electrolyte outlet channel from the other end on one side of the ion membrane, and returns to the storage tank through the positive electrolyte outlet flow channel 12 and enters the common channel; the negative electrolyte enters the common flow channel 9 of the stack electrolyte from the storage tank through a pump, then reaches the channel outlet through the negative electrolyte inlet flow channel 11, and then enters the reaction electrode placed on the bipolar plate on the other side of the ion membrane to carry out the electrochemical reaction of charge and discharge. Then, it enters the inlet of the negative electrolyte outlet channel from the other end on the other side of the ion membrane, and returns to the storage tank through the negative electrolyte outlet flow channel 13 and enters the common channel; during this process, the positive electrolyte flows on the positive side and in the positive flow channel, and the negative electrolyte flows on the negative side and in the negative flow channel without mixing with each other. The positive and negative electrolytes do not mix with each other and do not leak.

[0028] Further, the present invention adopts a structure in which a rubber sheet is stacked between multiple groups of hard plastic flow channel plates to form a current-limiting channel. This structure can well offset the warping influence of the hard plates of the flow channel plates.

[0029] Further, the upper and lower ends and the central area of the current-limiting channel of the hard plastic flow channel plate of the present invention are of a completely through structure. The structure is made of hard plastic in the horizontal direction, which can well guide the liquid to flow smoothly in the set direction. It is made of soft rubber in the vertical direction, which can well isolate the liquid and ensure that the electrolyte does not leak or mix at the flow channel.

[0030] Further, the material of the flow channel plate 8 is one of polypropylene (PP), acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (PA), modified polyvinyl chloride (CPVC), polyvinyl chloride (PVC), polyoxymethylene (POM), polyphenylene oxide (PPO), polyphenylene sulfide (PPS), polyether ether ketone (PEEK) or polysulfone (PSF).

[0031] As shown in Figure 4 and Figure 5 As shown, the present invention forms an integral sealing structure through a rubber sheet. The advantages of this structure compared with the prior art using multiple sealing rings are as follows: the stack sealing structure of the present invention is composed of only one compressible and deformable rubber sheet in each single cell and other components that are not deformed under pressure. The sealing parts include the common channel seal, the inlet and outlet flow channel seals of the positive and negative electrolytes, the bipolar plate seal, the ion membrane seal, and the outer seal of the stack. On the one hand, the present invention reduces the number of sealing rings, and on the other hand, it reduces the cumbersome installation process of the sealing rings. At the same time, the sealing rings generally used in the prior art are O-rings, and the compression sealing area is small and prone to leakage. However, the present invention uses a large sealing surface for the rubber sheet to be compressed and sealed, which can effectively improve the sealing reliability of the stack.

[0032] Further, the thickness of the rubber plate 6 is 0.4 - 5.0 mm, and the compression amount range at the extrusion seal formed by the rubber plate is 11% - 61%. The structure of the rubber plate is a flat plate, and holes can be opened on the rubber plate as needed.

[0033] Further, the material of the rubber plate 6 is one of ethylene propylene diene monomer rubber (EPDM), butyl rubber (IIR), nitrile butadiene rubber (NBR), soft rubber thermoplastic rubber (TPR), thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), and thermoplastic dynamically vulcanized elastomer (TPV).

[0034] In this embodiment, the flow battery is an iron-chromium flow battery, a vanadium redox flow battery, a vanadium-iron flow battery, or an organic flow battery.

[0035] Example 2 An embodiment of the present invention takes a 100V 33kW iron-chromium flow battery stack as an example. The stack is mainly composed of 88 single cells stacked and assembled. Each single cell consists of 1 flow channel plate frame, 1 rubber plate, 2 electrodes, 1 ion membrane, and 1 bipolar plate. Among them, the material of the rubber plate is ethylene propylene diene monomer (EPDM), with a thickness of 2.2 mm; the material of the flow channel plate frame is polypropylene, with a thickness of 6 mm, and its flow channel part is through; the ion membrane diaphragm is a sulfonic acid-based proton exchange membrane, with a thickness of 50 microns; the bipolar plate is a graphite molded plate with a flow channel, with a thickness of 6 mm; the electrode material is carbon cloth, with a thickness of 0.8 mm. The stack sealing structure is composed of a compressible and deformable rubber plate and other components that do not deform under pressure. The sealing parts include the common channel seal, the inlet and outlet flow channel seals of the positive and negative electrolyte solutions, the bipolar plate seal, the ion membrane seal, and the outer seal of the stack. The compression amount of the rubber plate sealing part is 25%-30%. Four inlet and outlet flow channels for the electrolyte solution are symmetrically distributed in the up and down directions of the flow channel plate frame. Flow ports are provided at the end of each flow channel at the bottom and top of the flow channel plate frame. The position and size of the flow ports correspond to the inlet and outlet ports of the bipolar plate and cooperate to form a corresponding closed flow channel during assembly. There are 2 common channels for the electrolyte solution in the upper part of the flow channel plate frame. The two flow channels at the upper end of the flow channel plate frame are respectively communicated with the positive and negative liquid common channels on the end plate, and the two flow channels at the lower end of the flow channel plate frame are respectively communicated with the positive and negative liquid common channels on the end plate. The number of stack plate frames is 89, no sealing rings are used, and the number of rubber plates for sealing is 89. Both ends of the stack are aluminum end plates, and there are 88 groups of single cells in the middle. The stack is fixed by 16 bolts plus springs, and the pressing force is maintained at 20,000 N. When the stack works, the electrolyte solution flows from the positive and negative liquid storage tanks to the positive and negative inlet common channels under the push of a magnetic circulation pump, then passes through the positive and negative inlet flow channels to the outlet, and then enters the reaction electrodes placed on the bipolar plate on one side of the ion membrane for the electrochemical reaction of charge and discharge. Then it enters the inlet of the positive and negative electrolyte solution outlet flow channels, passes through the positive and negative outlet flow channels to enter the common channel and then returns to the positive and negative liquid storage tanks. During the charge and discharge process of the battery, the electrolyte solution always flows in the stack, and it is ensured that the positive and negative electrolyte solutions do not mix with each other and do not leak.

[0036] Testing is carried out using an electrolyte solution composed of 1.2M ferrous chloride + 1.3M chromium chloride + 2.5M hydrochloric acid. The charge and discharge power is 33 kW, the upper limit voltage for charging is 105.6 V, the lower limit voltage for discharging is 70.4 V, the flow rate of the positive and negative electrodes is 24 m 3 / h, the electrolyte solution temperature is 65 °C, and the battery test results are a current efficiency of 96%, an energy efficiency of 81%, and an electrolyte solution capacity of 10 kwh / m 3。In the prior art, the bipolar plate seal, diaphragm seal, common channel seal and external seal are achieved through sealing rings. The number of sealing rings for each stack is 1,097. Each single cell has one positive and one negative plate frame, and the total number of plate frames is 180. The stack assembly reduces the process step of pre-installing sealing rings, the material cost of the stack drops by 15%, and the passing rate of the airtightness detection of the stack at the end of the production line reaches 100%.

[0037] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flow battery stack, characterized in that, The stack is composed of an end plate (1), a current collector (2) and single cells (3). Each single cell (3) is a laminated structure consisting of a bipolar plate (4), a rubber plate (6), a flow channel plate frame (8), an ion membrane (7) and two electrodes (5). Under the action of the bipolar plate (4), the rubber plate (6) is pressed against the flow channel plate frame (8) to form a closed and sealed common electrolyte flow channel (9). The same rubber plate is squeezed at different positions to form multiple sealing structures, specifically including: 1) The partial lamination of the rubber plate and the flow channel plate frame forms the common flow channel and the seals of the inlet and outlet liquid flow channels; 2) The laminated structure of the rubber plate, the flow channel plate frame and the bipolar plate forms the bipolar plate seal; 3) The laminated part of the rubber plate and the ion membrane plate frame forms the ion membrane seal; 4) The lamination of the rubber plate and the flow channel plate frame forms the external seal of the stack and the seal of the common electrolyte flow channel.

2. The flow battery stack according to claim 1, characterized in that: In the flow battery stack, two adjacent rubber plates (6) and the flow channel plate frame (8) located therebetween form 4 current-limiting flow channels, namely the positive electrolyte inlet flow channel (10), the positive electrolyte outlet flow channel (12), the negative electrolyte inlet flow channel (11) and the negative electrolyte outlet flow channel (13).

3. The flow battery stack according to claim 2, wherein: There is only one flow channel plate frame (8) in each single cell of the flow battery stack. The positive electrolyte inlet flow channel (10), the positive electrolyte outlet flow channel (12), the negative electrolyte inlet flow channel (11) and the negative electrolyte outlet flow channel (13) are respectively arranged at 4 independent positions of the flow channel plate frame, and the flow channel depth is the entire thickness of the plate frame, that is, the 4 current-limiting flow channels penetrate the flow channel plate frame.

4. The flow battery stack according to claim 1, characterized in that: In the flow battery stack, the adjacent flow channel plate frames are partially stacked together on the outside to limit the position of each flow channel plate frame along the axial direction of the stack, ensuring the consistency of the compression amount at the sealing part formed by each rubber plate and forming a stable sealing structure of the stack.

5. The flow battery stack according to claim 1, wherein: In the flow battery stack, the positive electrolyte enters the common electrolyte flow channel (9) of the stack from the storage tank through the pump, then reaches the flow channel outlet through the positive electrolyte inlet flow channel (10), and then enters the reaction electrode placed on the bipolar plate on one side of the ion membrane to carry out the electrochemical reaction of charge and discharge. Then it enters the inlet of the positive electrolyte outlet channel from the other end on one side of the ion membrane, and returns to the storage tank through the common channel after passing through the positive electrolyte outlet flow channel (12). The negative electrolyte enters the common electrolyte flow channel (9) of the stack from the storage tank through the pump, then reaches the channel outlet through the negative electrolyte inlet flow channel (11), and then enters the reaction electrode placed on the bipolar plate on the other side of the ion membrane to carry out the electrochemical reaction of charge and discharge. Then it enters the inlet of the negative electrolyte outlet channel from the other end on the other side of the ion membrane, and returns to the storage tank through the common channel after passing through the negative electrolyte outlet flow channel (13). During this process, the positive and negative electrolytes do not mix with each other and do not leak.

6. The flow battery stack according to claim 1, characterized in that: The material of the flow channel plate frame (8) is one of polypropylene PP, acrylonitrile-butadiene-styrene copolymer ABS, polyamide PA, modified polyvinyl chloride CPVC, polyvinyl chloride PVC, polyoxymethylene POM, polyphenylene ether PPO, polyphenylene sulfide PPS, polyether ether ketone PEEK or polysulfone PSF.

7. The flow battery stack according to claim 4, wherein: The thickness of the rubber plate (6) is 0.4 - 5.0 mm, and the compression amount range at the extrusion seal formed by the rubber plate is 11% - 61%.

8. The flow battery stack according to claim 1, wherein: The material of the rubber plate (6) is one of ethylene propylene diene monomer rubber (EPDM), butyl rubber (IIR), nitrile butadiene rubber (NBR), soft rubber thermoplastic rubber (TPR), thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), and thermoplastic dynamically vulcanized elastomer (TPV).

9. The flow battery stack according to claim 1, wherein: The flow battery is an iron-chromium flow battery, a vanadium redox flow battery, a vanadium-iron flow battery, or an organic flow battery.

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