A liquid flow battery stack

Abstract

The present invention belongs to the technical field of liquid flow batteries and specifically discloses a liquid flow battery stack, which is composed of end plates, current collectors, and single cells. Each single cell is a stacked structure consisting of a bipolar plate, a rubber plate, a flow plate frame, an ion membrane, and two electrodes. Under the force of the bipolar plate, the rubber plate is pressed against the flow 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: the rubber plate and the flow plate frame are partially stacked to form a common flow channel and liquid inlet and outlet flow channel seals; the rubber plate, the flow plate frame, and the bipolar plate stack structure form a bipolar plate seal; the rubber plate and the ion membrane frame are partially stacked to form an ion membrane seal; and the rubber plate and the flow plate frame are stacked to form a stack external seal and a common electrolyte flow channel seal. The present invention concentrates the stack sealing components on a single rubber plate, greatly reducing the use of sealing rings, reducing the risk of stack leakage, and improving stack reliability.

Description

Technical Field

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

[0002] Energy storage technology is an effective strategy for addressing issues such as the efficient utilization of renewable energy and environmental pollution. Among the many energy storage technologies currently available, flow batteries, with their excellent safety and long service life, are ideal for long-term energy storage applications. In flow batteries, the stack is the core component, and the stability of its performance is directly related to the performance and cost of the entire system. Flow batteries charge and discharge by circulating an electrolyte liquid within the stack, causing the electrolyte to undergo electrochemical oxidation-reduction reactions at the positive and negative electrodes, respectively. This stores and releases electrical energy in the electrolyte, achieving the conversion of electrical energy into chemical energy. The electrolyte is divided into positive and negative electrolytes. When using a stack, it is important to ensure that the positive and negative electrolytes do not mix within the stack and that the electrolyte does not leak outside the stack. This requires ensuring the long-term sealing of the stack.

[0003] Usually, the basic structure of a fuel cell stack includes positive and negative plate frames, bipolar plates, electrodes and ion membranes. At the same time, a common channel and a current limiting channel for the electrolyte are also set on the fuel cell structure. In order to ensure the normal operation of the fuel cell stack, the sealing between these components is very important. Multiple rubber sealing rings are required to ensure the sealing of the electrolyte. The installation of the sealing rings requires a lot of manpower. At the same time, since the bipolar plates used in the fuel cell stack are graphite plates with a small temperature coefficient, and the plate frames are usually plastic with a large temperature coefficient, this will cause the bipolar plates and the plate frames to be easily displaced and misaligned due to temperature changes when the battery is in use, resulting in reduced 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, and each single battery requires a plate frame for the positive and negative electrodes, the number of components is large, and the cost is high. Summary of the Invention

[0004] In response to the technical deficiencies of the existing liquid flow battery stack structure, the present invention provides a new structure of liquid flow battery stack, which solves the problem of multiple sealing problems of the liquid flow battery stack through a rubber plate, and ensures the sealing stability of multiple materials under inconsistent thermal expansion coefficients, thereby improving the long-term reliability of the stack. At the same time, it reduces the use of stack plates and frames, which is conducive to reducing the cost of the stack and solving the problems mentioned in the above background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a liquid flow battery stack, the stack consisting of end plates, current collectors and single cells, wherein each single cell is a stacked structure consisting of a bipolar plate, a rubber plate, a flow channel plate frame, an ion membrane and two electrodes;

[0006] The rubber plate is pressed against the flow channel plate frame under the force of the bipolar plate to form a closed and sealed common electrolyte flow channel;

[0007] The same rubber plate is squeezed at different positions to form multiple sealing structures, including: 1) the rubber plate and the flow plate frame are partially stacked to form a common flow channel and the liquid inlet and outlet flow channel seals; 2) the rubber plate, the flow plate frame, and the bipolar plate stack structure form the bipolar plate seal; 3) the rubber plate and the ion membrane plate frame stack part form the ion membrane seal; 4) the rubber plate and the flow plate frame are stacked to form the external seal of the battery stack and the electrolyte common flow channel seal.

[0008] Preferably, two adjacent rubber plates in the liquid flow battery stack and the flow channel frame located therebetween constitute four flow limiting channels, namely the positive electrode electrolyte inlet channel, the positive electrode electrolyte outlet channel and the negative electrode electrolyte inlet channel, the negative electrode electrolyte outlet channel.

[0009] Preferably, there is only one flow channel plate frame in each single cell of the liquid flow battery stack, and the positive electrode electrolyte inlet flow channel, positive electrode electrolyte outlet flow channel, negative electrode electrolyte inlet flow channel and negative electrode electrolyte outlet flow channel are respectively arranged at four independent positions of the flow channel plate frame, and the flow channel depth is the entire plate frame thickness, that is, the four flow limiting channels pass through the flow channel plate frame.

[0010] Preferably, adjacent flow channel plate frames in the flow battery stack are partially stacked together on the outside to form axial limit of each flow channel plate frame along the stack, ensuring the consistency of the compression amount of each rubber plate forming the seal, forming a stable sealing structure of the stack.

[0011] Preferably, in a flow battery stack, the positive electrode electrolyte enters the common electrolyte flow channel of the stack from the storage tank through a pump, then passes through the positive electrode electrolyte inlet flow channel to reach the flow channel outlet, then enters the reaction electrode placed on the bipolar plate on one side of the ion membrane to perform the electrochemical reaction of charge and discharge, then enters the inlet of the positive electrode electrolyte outlet channel from the other end of the ion membrane, enters the common channel through the positive electrode electrolyte outlet flow channel and returns to the storage tank;

[0012] The negative electrode electrolyte enters the common flow channel of the battery stack electrolyte from the storage tank through a pump, then passes through the negative electrode electrolyte inlet flow channel to reach the channel outlet, and then enters the reaction electrode placed on the bipolar plate on the other side of the ion membrane to carry out electrochemical reactions of charging and discharging, and then enters the inlet of the negative electrode electrolyte outlet channel from the other end of the other side of the ion membrane, enters the common channel through the negative electrode electrolyte outlet flow channel and returns to the storage tank; in this process, the positive and negative electrode electrolytes do not mix with each other and do not leak.

[0013] Preferably, the flow channel plate frame material 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, polyetheretherketone PEEK or polysulfone PSF.

[0014] Preferably, the thickness of the rubber sheet is 0.4-5.0 mm, and the compression range of the rubber sheet where the extrusion seal is formed is 11%-61%.

[0015] Preferably, the material of the rubber plate is one of ethylene propylene diene monomer rubber EPDM, butyl rubber IIR, nitrile rubber NBR, soft thermoplastic rubber TPR, thermoplastic polyurethane TPU, thermoplastic elastomer TPE, and thermoplastic dynamically vulcanized elastomer TPV.

[0016] Preferably, the flow battery is an iron-chromium flow battery, an all-vanadium flow battery, a vanadium-iron flow battery or an organic flow battery.

[0017] The beneficial effects of the present invention are: the liquid flow battery stack structure provided by the present invention concentrates the stack sealing components on a rubber plate, greatly reducing the use of sealing rings, reducing the risk of leakage of the stack, and improving the reliability of the stack. At the same time, the through-flow channel structure on the flow channel plate frame is conducive to the production of thinner liquid flow battery cells. In addition, the stack structure design reduces the installation process, significantly improves the efficiency of the stack assembly, and greatly reduces the labor intensity of the assemblers, thereby reducing the cost of the stack in terms of materials and manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the appearance of a flow battery stack in Example 1 of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of a single cell in a flow battery stack in Example 1 of the present invention;

[0020] Figure 3 This is a schematic diagram of the partial sealing structure of the flow battery stack in Example 1 of the present invention;

[0021] Figure 4 Schematic diagram of electrolyte flow in the flow channel frame in Example 1 of the present invention;

[0022] Figure 5 This is a schematic diagram of the rubber plate structure in Example 1 of the present invention;

[0023] 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 frame; 9-electrolyte common flow channel; 10-positive electrode electrolyte inlet flow channel; 11-negative electrode electrolyte inlet flow channel; 12-positive electrode electrolyte outlet flow channel; 13-negative electrode electrolyte outlet flow channel. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] It should be noted that, unless there is a conflict, the embodiments and features of the embodiments of the present invention may be combined with each other. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.

[0026] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is typically placed when in use, or are the orientations or positional relationships commonly understood by those skilled in the art. These terms are intended only to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0028] Example 1

[0029] The present invention provides a technical solution: a liquid flow battery stack, such as Figure 1 As shown, the stack is composed of an end plate 1, a current collector 2 and a single cell 3, wherein Figure 2 As shown, each single cell 3 is a stacked 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;

[0030] like Figure 3 As 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 electrolyte common flow channel 9.

[0031] Furthermore, the upper part of this electrolyte common flow channel is a graphite bipolar plate, and the lower part is a hard plastic flow channel plate frame, which forms a sealed and reliable liquid flow collection area with the lateral (left and right) rubber plates (a liquid channel is opened on the right side of the rubber plate to facilitate the flow of electrolyte to the right).

[0032] Because the bipolar plates and plastic flow channel plate frames are both made of thin hard plastic materials, warping problems are prone to occur during injection molding, which affects the sealing effect. The present invention changes the number of plate frames in a single battery from 2 to 1, thereby increasing the thickness of the plate frame and reducing the occurrence of warping. At the same time, the compressible rubber plate in the middle layer during sealing can reduce or absorb the impact of warping of the bipolar plates or flow channel plate frames on the sealing, thereby improving the sealing of the liquid flow battery stack.

[0033] The same rubber sheet is compressed at different locations to form multiple sealing structures, including: 1) The rubber sheet and the flow plate frame are partially laminated to form the common flow channel and the inlet and outlet flow channel seals; 2) The rubber sheet, flow plate frame, and bipolar plate laminated structure form the bipolar plate seal; 3) The rubber sheet and the ion membrane plate frame laminated structure form the ion membrane seal; 4) The rubber sheet and the flow plate frame laminated structure form the stack external seal and the electrolyte common flow channel seal. This new structure solves the problem of multiple sealing points in the flow battery stack with a single rubber sheet, and ensures the sealing stability of multiple materials with inconsistent thermal expansion coefficients, improving the long-term reliability of the stack while reducing the number of stack plates and frames, which helps reduce the cost of the stack.

[0034] Furthermore, the two adjacent rubber plates 6 in the liquid flow battery stack and the flow channel frame 8 located therebetween constitute four flow limiting channels, namely the positive electrode electrolyte inlet channel 10, the positive electrode electrolyte outlet channel 12 and the negative electrode electrolyte inlet channel 11, and the negative electrode electrolyte outlet channel 13.

[0035] Furthermore, each cell in the flow battery stack has only one flow channel plate frame 8, such as Figure 3 and Figure 4 As shown, the positive electrode electrolyte inlet flow channel 10, the positive electrode electrolyte outlet flow channel 12, the negative electrode electrolyte inlet flow channel 11 and the negative electrode electrolyte outlet flow channel 13 are respectively arranged at four independent positions of the flow channel plate frame, and the flow channel depth is the entire plate frame thickness, that is, the four current limiting flow channels are through the flow channel plate frame. Furthermore, the positive electrode flow channel and the negative electrode flow channel portion of the frame plate are longitudinally through-structured. In the prior art, each single cell is composed of two plate frames, positive and negative, and the positive electrode flow channel is arranged on the positive plate frame, and the negative electrode 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 flow channel cross-sectional area to reduce the flow channel flow resistance, which makes the plane area of ​​the single cell large, which is not conducive to improving the power density of the battery stack and reducing costs. The independent through-type plate frame flow channel of the present invention overcomes the above shortcomings and is conducive to the production of thinner battery stacks.

[0036] Furthermore, adjacent flow channel plate frames in the flow battery stack are partially stacked together on the outside to form axial limits for each flow channel plate frame along the stack, ensuring the consistency of the compression amount of each rubber plate forming the seal, thereby forming a stable sealing structure for the stack.

[0037] Furthermore, in the flow battery stack, the positive electrode electrolyte enters the common flow channel 9 of the battery stack through the pump from the storage tank, then reaches the flow channel outlet through the positive electrode electrolyte inlet channel 10, and then enters the reaction electrode placed on the bipolar plate on one side of the ion membrane to perform the electrochemical reaction of charge and discharge, and then enters the inlet of the positive electrode electrolyte outlet channel from the other end of the ion membrane, enters the common channel through the positive electrode electrolyte outlet channel 12 and returns to the storage tank; the negative electrode electrolyte enters the common flow channel 9 of the battery stack from the storage tank through the pump, and then It passes through the negative electrode electrolyte inlet channel 11 to reach the channel outlet, 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, and then enters the negative electrode electrolyte outlet channel inlet from the other end of the other side of the ion membrane, enters the common channel through the negative electrode electrolyte outlet channel 13 and returns to the liquid storage tank; in this process, the positive electrode electrolyte flows on the positive electrode side and in the positive electrode flow channel, and the negative electrode electrolyte flows on the negative electrode side and in the negative electrode flow channel without mixing with each other, and the positive and negative electrode electrolytes do not mix with each other and do not leak.

[0038] Furthermore, the present invention adopts a structure in which a rubber plate is stacked between multiple groups of hard plate plastic flow channel frames to form a flow limiting channel. This structure can effectively offset the warping effect of the hard plate of some flow channel frames.

[0039] Furthermore, the rigid plastic flow channel frame of the present invention features a completely continuous structure at the upper and lower flow-restricting channels and in the center. This structure, constructed horizontally of rigid plastic, effectively guides the liquid to flow smoothly in the desired direction. The longitudinal section, constructed of soft rubber, effectively isolates the liquid, preventing electrolyte crosstalk and mixing within the flow channel.

[0040] Furthermore, the material of the flow channel 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, polyetheretherketone PEEK or polysulfone PSF.

[0041] Figure 4 and Figure 5As shown, the present invention forms an integral sealing structure through a rubber plate. Compared with the prior art using multiple sealing rings, the advantages of this structure are: the sealing structure of the battery stack of the present invention is composed of only one compressible and deformable rubber plate in each single cell and other components that do not deform under pressure. The sealing parts include common channel seals, liquid inlet and outlet seals for positive and negative electrolytes, bipolar plate seals, ion membrane seals, and external seals for the battery stack. On the one hand, the present invention reduces the number of sealing rings, and on the other hand, it reduces the tedious sealing ring installation process. At the same time, the sealing rings used in the prior art are generally O-rings, which have a small compression sealing area and are prone to leakage. However, the present invention uses a rubber plate with a large compression sealing surface, which can effectively improve the sealing reliability of the battery stack.

[0042] Furthermore, the thickness of the rubber plate 6 is 0.4-5.0 mm, and the compression range of the rubber plate where the rubber plate forms an extrusion seal is 11%-61%. The rubber plate is a flat plate with holes formed on it as needed.

[0043] Furthermore, the material of the rubber plate 6 is one of ethylene propylene diene monomer rubber EPDM, butyl rubber IIR, nitrile rubber NBR, soft thermoplastic rubber TPR, thermoplastic polyurethane TPU, thermoplastic elastomer TPE, and thermoplastic dynamically vulcanized elastomer TPV.

[0044] In this embodiment, the flow battery is an iron-chromium flow battery, an all-vanadium flow battery, a vanadium-iron flow battery or an organic flow battery.

[0045] Example 2

[0046] The present invention uses a 100V, 33kW iron-chromium flow battery stack as an example. The stack is primarily composed of 88 stacked cells, each consisting of a flow channel frame, a rubber plate, two electrodes, an ion membrane, and a bipolar plate. The rubber plate is made of EPDM rubber and is 2.2mm thick. The flow channel frame is made of polypropylene and is 6mm thick, with a through-flow channel. The ion membrane separator is a sulfonic acid-based ion exchange membrane and is 50 microns thick. The bipolar plates are 6mm thick graphite molded plates with flow channels. The electrodes are made of carbon cloth and are 0.8mm thick. The stack seal structure is constructed from a compressible rubber plate and other components that do not deform under pressure. The seals include the common channel seal, the positive and negative electrolyte inlet and outlet seals, the bipolar plate seal, the ion membrane seal, and the stack exterior seal. The rubber plate seals are compressed by 25%-30%. There are four electrolyte inlet and outlet channels symmetrically distributed in the upper and lower directions of the channel frame. A channel opening is provided at the end of each channel at the bottom and top of the channel frame. The position and size of the channel opening correspond to the inlet and outlet of the bipolar plate, and cooperate with them to form a one-to-one closed channel during assembly. There are two electrolyte common channels on the upper part of the channel frame. The two channels at the upper end of the channel frame are connected to the positive and negative liquid common channels on the end plate respectively, and the two channels at the lower end of the channel frame are connected to the positive and negative liquid common channels on the end plate respectively. There are 89 plate frames in the battery stack. No sealing rings are used. There are 89 rubber plates used for sealing. There are aluminum end plates at both ends of the battery stack and 88 groups of single batteries in the middle. The battery stack is fixed with 16 bolts and springs to maintain a clamping force of 20,000N. When the stack is operating, the electrolyte, driven by a magnetic circulation pump, flows from the positive and negative electrode storage tanks to the common inlet channel for the positive and negative electrodes. It then flows through the positive and negative electrode inlet channels to the outlets, then enters the reaction electrodes on the bipolar plates on one side of the ion membrane for the electrochemical reaction of charge and discharge. It then flows from the inlet of the positive and negative electrode electrolyte outlet channels, through the positive and negative electrode outlet channels, into the common channel, and back to the positive and negative electrode storage tanks. During the battery's charge and discharge process, the electrolyte is kept flowing in the stack, ensuring that the positive and negative electrolytes do not mix or leak.

[0047] The test was conducted using an electrolyte consisting of 1.2M ferrous chloride + 1.3M chromium chloride + 2.5M hydrochloric acid. The charge and discharge power was 33kw, the upper limit voltage for charging was 105.6V, the lower limit voltage for discharging was 70.4V, and the positive and negative electrode flow rates were 24m 3 / h, the electrolyte temperature is 65℃, the battery test results are current efficiency 96%, energy efficiency 81%, and electrolyte capacity 10kwh / m 3Existing technology uses sealing rings to achieve bipolar plate sealing, diaphragm sealing, common channel sealing, and external sealing. Each stack has 1,097 sealing rings, and each single cell has one positive plate frame and one negative plate frame, for a total of 180 plates and frames. Stack assembly reduces the need for pre-installed sealing rings, reducing stack material costs by 15%, and achieving a 100% pass rate for end-of-line stack airtightness testing.

[0048] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A liquid flow battery stack, characterized in that: The battery stack is composed of an end plate (1), a current collector (2) and a single cell (3), wherein each single cell (3) is a stacked 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); 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 electrolyte common flow channel (9); The same rubber plate is squeezed at different positions to form multiple sealing structures, including: 1) the rubber plate and the flow plate frame are partially stacked to form a common flow channel and the liquid inlet and outlet flow channel seals; 2) the rubber plate, the flow plate frame, and the bipolar plate stack structure form the bipolar plate seal; 3) the rubber plate and the ion membrane plate frame stack part form the ion membrane seal; 4) the rubber plate and the flow plate frame are stacked to form the external seal of the battery stack and the electrolyte common flow channel seal.

2. The flow battery stack according to claim 1, characterized in that: Two adjacent rubber plates (6) in a liquid flow battery stack and a flow channel frame (8) located therebetween form four flow limiting channels, namely, a positive electrode electrolyte inlet channel (10), a positive electrode electrolyte outlet channel (12), and a negative electrode electrolyte inlet channel (11), and a negative electrode electrolyte outlet channel (13).

3. The flow battery stack according to claim 2, characterized in that: Each single cell of the flow battery stack has only one flow channel plate frame (8), and the positive electrode electrolyte inlet flow channel (10), the positive electrode electrolyte outlet flow channel (12), the negative electrode electrolyte inlet flow channel (11), and the negative electrode electrolyte outlet flow channel (13) are respectively arranged at four independent positions of the flow channel plate frame, and the flow channel depth is the entire plate frame thickness, that is, the four flow limiting flow channels are through the flow channel plate frame.

4. The flow battery stack according to claim 1, characterized in that: Adjacent flow channel plates and frames in the flow battery stack are stacked together on the outside to form axial limits for each flow channel plate and frame along the stack, ensuring the consistency of the compression amount at the sealing point formed by each rubber plate, thus forming a stable sealing structure for the stack.

5. The flow battery stack according to claim 1, characterized in that: In the flow battery stack, the positive electrode electrolyte enters the common electrolyte flow channel (9) of the stack from the storage tank through the pump, then passes through the positive electrode electrolyte inlet flow channel (10) to reach the flow channel outlet, then enters the reaction electrode placed on the bipolar plate on one side of the ion membrane to perform the electrochemical reaction of charge and discharge, then enters the inlet of the positive electrode electrolyte outlet channel from the other end of the ion membrane, enters the common channel through the positive electrode electrolyte outlet flow channel (12) and returns to the storage tank; The negative electrode electrolyte enters the common flow channel (9) of the battery stack electrolyte from the storage tank through the pump, then reaches the channel outlet through the negative electrode electrolyte inlet channel (11), and then enters the reaction electrode placed on the bipolar plate on the other side of the ion membrane to perform the electrochemical reaction of charge and discharge, and then enters the inlet of the negative electrode electrolyte outlet channel from the other end of the other side of the ion membrane, enters the common channel through the negative electrode electrolyte outlet channel (13) and returns to the storage tank; in this process, the positive and negative electrode 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 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), polyetheretherketone (PEEK) or polysulfone (PSF).

7. The flow battery stack according to claim 4, characterized in that: The thickness of the rubber sheet (6) is 0.4-5.0 mm, and the compression range of the rubber sheet where the rubber sheet forms an extrusion seal is 11%-61%.

8. The flow battery stack according to claim 1, characterized in that: The material of the rubber plate (6) is one of ethylene propylene diene monomer rubber EPDM, butyl rubber IIR, nitrile rubber NBR, and thermoplastic elastomer TPE.

9. The flow battery stack according to claim 1, characterized in that: The flow battery is an iron-chromium flow battery, an all-vanadium flow battery, a vanadium-iron flow battery or an organic flow battery.

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