A cell stack of a flow battery, a flow battery system

Abstract

The application relates to the field of liquid flow batteries, and provides a battery stack of a liquid flow battery and a liquid flow battery system. The battery stack comprises a plurality of battery units stacked in a thickness direction. The battery unit comprises: a first bipolar plate, the first bipolar plate is provided with a first recess on a first surface and a second flow channel on a second surface, and the first recess of the first surface penetrates through a liquid flow through hole to the second flow channel of the second surface; a liquid path connector, the liquid path connector comprises a first connecting piece and a second connecting piece, a butt joint part of the first connecting piece is embedded in the first recess, the first recess and the butt joint part have corresponding shapes, a first liquid flow channel is arranged in the first connecting piece, and the first liquid flow channel is provided with a butt joint hole corresponding to the liquid flow through hole at the butt joint part; the second connecting piece is used for being connected with an external electrolyte pipeline, a second liquid flow channel is arranged in the second connecting piece, and the second liquid flow channel is connected with the first liquid flow channel.

Description

Technical Field

[0001] This application relates to the field of flow batteries, and more particularly to a flow battery stack and a flow battery system. Background Technology

[0002] A flow battery stack consists of multiple individual cells stacked along its thickness. The electrolyte needs to enter and exit channels on each bipolar plate to contact the electrodes covering those channels and react with them. In related technologies, through-holes for electrolyte entry and exit from the bipolar plates are typically located on the side of the bipolar plates. Therefore, the bipolar plate thickness needs to be greater than the diameter of the through-holes, limiting the reduction of bipolar plate thickness and the increase of electrolyte flow rate. This means that the through-hole diameter and bipolar plate thickness cannot be independently optimized. Furthermore, the through-holes need to be connected to external liquid channels via O-rings. The periphery of the through-hole is subjected to long-term stress from the O-rings, making the thin and brittle graphite material around the through-hole prone to cracking under stress, thus affecting the service life of the bipolar plates. Summary of the Invention

[0003] The main objective of this application is to provide a flow battery stack and flow battery system that aims to decouple the bipolar plate thickness from the through-hole diameter.

[0004] In a first aspect, this application provides a flow battery stack, the battery stack comprising: It includes multiple battery cells stacked along the thickness direction, the battery cells comprising: A first bipolar plate, comprising a first surface and a second surface opposite to each other, wherein the plane containing the first surface and the second surface is perpendicular to the thickness direction; wherein a first recess is provided on the first surface, and a second flow channel is provided on the second surface, and the first recess on the first surface is connected to the second flow channel on the second surface through a liquid flow hole. A liquid circuit connector includes a first connector and a second connector. The mating portion of the first connector is embedded in a first recessed portion, and the first recessed portion and the mating portion have corresponding shapes. A first liquid flow channel is provided in the first connector, and the first liquid flow channel forms a mating hole in the mating portion for corresponding to the liquid flow orifice. The second connector is used to connect to an external electrolyte pipeline. A second liquid flow channel is provided in the second connector, and the second liquid flow channel is connected to the first liquid flow channel. The electrolyte in the external electrolyte pipeline enters the second flow channel of the second surface sequentially through the second flow channel, the first flow channel, the docking hole, and the flow hole of the liquid connector; or, the electrolyte in the second flow channel enters the external electrolyte pipeline sequentially through the flow hole, the docking hole of the liquid connector, the first flow channel, and the second flow channel.

[0005] Secondly, this application also provides a liquid circuit connector, which includes a first connector and a second connector. The first connector includes a mating portion and a first liquid flow channel is provided within the first connector. The first liquid flow channel forms a mating hole in the mating portion. The mating hole is used to mate with a liquid flow hole on a first surface of a bipolar plate. The plane containing the first surface is perpendicular to the thickness direction of the bipolar plate. The second connector is used to connect to an external electrolyte pipeline. The second connector includes a second liquid flow channel, which is connected to the first liquid flow channel. The electrolyte in the external electrolyte pipeline enters the second flow channel on the second surface of the bipolar plate sequentially through the second flow channel, the first flow channel, the docking hole, and the flow hole of the liquid circuit connector; or, the electrolyte in the second flow channel enters the external electrolyte pipeline sequentially through the flow hole, the docking hole of the liquid circuit connector, the first flow channel, and the second flow channel.

[0006] This application provides a flow battery stack and a flow battery system, which provides electrolyte to each battery cell through a liquid circuit connector, allowing the liquid flow holes to be set on the surface of the bipolar plate perpendicular to the thickness direction. This avoids setting the through holes on the side of the bipolar plate, thereby avoiding the thickness limitation of the bipolar plate caused by the size of the through hole diameter, as well as the diameter limitation of the through hole caused by the thickness of the bipolar plate. This achieves decoupling between the thickness of the bipolar plate and the diameter of the through hole, and improves the service life of the bipolar plate. Attached Figure Description

[0007] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the structure of a bipolar plate in related technologies; Figure 2 This is a schematic diagram of the structure of a bipolar plate in related technologies; Figure 3 This is a schematic diagram of the structure of a battery cell provided in one embodiment of this application; Figure 4 A cross-sectional schematic diagram of a battery cell provided in an embodiment of this application. Figure 5 A cross-sectional schematic diagram of a fluid circuit connector provided in an embodiment of this application; Figure 6This is a schematic diagram of the structure of a fluid circuit connector provided in one embodiment of this application; Figure 7 This is a partial schematic diagram of a battery stack provided in an embodiment of this application; Figure 8 A schematic diagram of the electrolyte flow direction provided in an embodiment of this application. Figure 9 This is a partially enlarged schematic diagram of the locking part provided in an embodiment of this application; Figure 10 This is a schematic diagram of the structure of a battery cell provided in another embodiment of this application; Figure 11 A physical drawing of a fluid circuit connector provided in one embodiment of this application; Figure 12 A schematic diagram of the structure of the first bipolar plate and the second bipolar plate provided in an embodiment of this application; Figure 13 A schematic diagram of the structure of the first bipolar plate and the second bipolar plate provided in another embodiment of this application; Figure 14 This is a schematic diagram of the structure of a liquid circuit connector provided in an embodiment of this application.

[0009] Explanation of reference numerals in the attached drawings: 11, First bipolar plate; 12, Liquid connector; 111, First recess; 112, Liquid flow hole; 113, Second flow channel; 121, First connector; 122, Second connector; 1211, Butt joint; 1212, Butt hole; 100, Battery stack; 1213, Sealing groove; 12111, First butt joint; 12112, Second butt joint; 12113, Locking part; 21, Second bipolar plate; 211, Second recess; 31, End plate. Detailed Implementation

[0010] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0011] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated, and the same reference numerals denote the same elements throughout.

[0012] To fully understand this invention, detailed structures and steps will be presented in the following description to illustrate the technical solution proposed by this invention. Preferred embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0013] Because the electrolyte in flow batteries is typically corrosive, the bipolar plates are usually made of corrosion-resistant graphite. However, graphite is brittle and prone to cracking, affecting the lifespan of the bipolar plates. To allow electrolyte to enter and exit the bipolar plates of each battery cell, related technologies typically use manifolds that run through the bipolar plates in the thickness direction of the battery stack. To prevent the bipolar plates from cracking at the through-holes, the thickness of the graphite around the through-holes usually needs to be increased, resulting in a larger bipolar plate thickness and making it impossible to supply electrolyte to each bipolar plate of each battery cell individually.

[0014] In related technologies, to provide electrolyte to the bipolar plates of each battery cell in the battery stack separately, through-holes may be provided on the side of the bipolar plates. Please refer to... Figure 1 , Figure 2 , Figure 1 , Figure 2 , Figure 1 , Figure 2 These are schematic diagrams of the structure of a bipolar plate in related technologies.

[0015] like Figure 1 As shown, a through-hole 20 is disposed on the side of the bipolar plate 10. In this case, the thickness of the bipolar plate 10 needs to be greater than the diameter of the through-hole 20, thus limiting the reduction of the thickness of the bipolar plate 10. Even if the electrochemical function of the battery cell can be achieved on a 5mm thick bipolar plate, the presence of the through-hole requires the bipolar plate to be at least 12mm thick, thus limiting the optimization of the single cell volume. At the same time, the diameter of the through-hole 20 needs to be smaller than the thickness of the bipolar plate 10, limiting the increase of the diameter of the through-hole 20, and thus limiting the increase of the electrolyte flow rate. Therefore, Figure 1 The structure shown results in a mutual constraint between the thickness of the bipolar plate 10 and the diameter of the through hole 20, which cannot be optimized independently.

[0016] by Figure 2 For example, in related technologies, in order to set the through hole 20 on the side of the bipolar plate 10, the thickness of the bipolar plate 10 needs to reach 15mm, while the diameter of the through hole 20 is limited to 9mm. To prevent the bipolar plate 10 from cracking at the through hole 20, a thickness of 3mm is required on both the top and bottom sides of the through hole. Furthermore, to prevent leakage of the electrolyte pipeline at the through hole 20, an O-ring is usually installed on the sealing plane 30 on the inner circumference of the through hole 20, which causes the hole wall to be subjected to stress perpendicular to the hole wall, increasing the risk of the graphite bipolar plate 10 cracking at the through hole 20.

[0017] To address the aforementioned problems, this application provides a flow battery stack.

[0018] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0019] Please refer to Figure 3 , Figure 4 , Figure 3 This is a schematic diagram of the structure of a battery cell provided in one embodiment of this application. Figure 4 This is a cross-sectional schematic diagram of a battery cell provided in an embodiment of this application.

[0020] like Figure 3 As shown, the battery cell provided in this embodiment includes a first bipolar plate 11 and a liquid circuit connector 12. The first bipolar plate 11 includes a first surface and a second surface that are opposite to and perpendicular to the thickness direction.

[0021] Figure 3 The first surface of the first bipolar plate 11 faces upwards, as shown in the image. Figure 3 As shown, a first recess 111 is provided on the first surface of the first bipolar plate 11, and a liquid flow hole 112 located in the first recess 111 extends from the first surface to the second surface. Figure 4 The second surface of the first bipolar plate 11 faces upwards, as shown in the image. Figure 4 As shown, a second flow channel 113 is provided on the second surface of the first bipolar plate 11, and the liquid flow hole 112 extends from the first recess 111 on the first surface to the second flow channel 113 on the second surface.

[0022] Please refer to Figure 5 , Figure 6 , Figure 5 This is a cross-sectional schematic diagram of a fluid circuit connector provided in one embodiment of this application. Figure 6 This is a schematic diagram of the structure of a liquid circuit connector provided in one embodiment of this application.

[0023] like Figure 5 As shown, the liquid connector 12 includes a first connector 121 and a second connector 122, and a first liquid flow channel is formed in the first connector 121 and a second liquid flow channel is formed in the second connector 122.

[0024] like Figure 6 As shown, the first connector 121 includes a mating portion 1211 whose shape corresponds to the first recess 111. Specifically, the mating portion 1211 has the same shape as the first recess 111, and the size of the mating portion 1211 is slightly smaller than that of the first recess 111, so that the mating portion 1211 can be accommodated in the first recess 111, thereby allowing the mating portion 1211 to be embedded in the first recess 111.

[0025] Please continue to refer to Figure 6 The first fluid flow channel has a docking hole 1212 formed in the docking portion 1211 for corresponding to the fluid flow hole 112. It can be understood that when the docking portion 1211 is accommodated in the first recess 111, the docking hole 1212 docks with the fluid flow hole 112, so that the liquid in the fluid connector 12 can leave the fluid connector through the docking hole 1212 and then enter the second flow channel 113 of the first bipolar plate 11 through the fluid flow hole 112; or so that the liquid in the second flow channel 113 of the first bipolar plate 11 can leave the first bipolar plate 11 through the fluid flow hole 112 and then enter the fluid connector 12 through the docking hole 1212.

[0026] Furthermore, the second connector 122 connects to an external electrolyte pipeline, which in turn connects to an electrolyte storage tank. The second connector can use a G-standard or NPT-standard external thread, quick-connect fitting, or hose barb for easy connection to the external electrolyte pipeline. The electrolyte supplied by the external electrolyte pipeline sequentially enters the second flow channel 113 on the second surface via the second flow channel 12, the first flow channel, the mating hole 1212, and the flow hole 112 of the liquid connector 12. Alternatively, the electrolyte after reaction in the second flow channel 113 sequentially enters the external electrolyte pipeline via the flow hole 112, the mating hole 1212 of the liquid connector 12, the first flow channel, and the second flow channel.

[0027] Please refer to Figure 7 , Figure 7 This is a partial schematic diagram of a battery stack provided in an embodiment of this application.

[0028] like Figure 7 As shown, multiple battery cells are stacked along the thickness direction to form a battery stack 100, wherein each battery cell is assembled from a first bipolar plate 11 and a liquid circuit connector 12. Specifically, a battery cell may be provided with multiple liquid circuit connectors 12, which are used for at least one of the following: anolyte inlet and outlet, and catholyte inlet and outlet.

[0029] The battery stack provided in this application embodiment provides electrolyte to each battery cell through a liquid channel connector. This allows the liquid flow holes to be located on the surface of the bipolar plate perpendicular to its thickness direction, avoiding the need to locate the holes on the side of the bipolar plate. This eliminates the thickness limitations imposed by the hole diameter on the bipolar plate, and the hole diameter limitations imposed by the bipolar plate thickness, thus decoupling the bipolar plate thickness from the hole diameter. Furthermore, the liquid channel connector provides electrolyte inlet and outlet channels for each battery cell, resulting in more uniform flow and pressure distribution, better consistency among the battery cells, improved electrolyte utilization, and easier individual monitoring, fault isolation, and maintenance of the battery cells.

[0030] In some embodiments, gaps may easily exist between the liquid flow hole 112 and the mating hole 1212, leading to leakage. To avoid this, a sealing groove 1213 is provided on the periphery of the mating hole 1212, and the sealing groove 1213 is filled with a seal.

[0031] Please continue to refer to Figure 4 , Figure 6 The outer periphery of the mating hole 1212 is provided with a sealing groove 1213 for filling the seal, wherein the seal can be an O-ring, a flat gasket, a sealant, etc.

[0032] Understandably, by using a seal to achieve a seal between the fluid connector 12 and the first bipolar plate 11, the first bipolar plate is only subjected to sealing pressure on its surface. Compared with the built-in O-ring, this reduces the risk of bipolar plate breakage and improves the service life of the bipolar plate.

[0033] In some embodiments, the first liquid flow channel is provided with a bend. When the electrolyte flows in the first liquid flow channel to the bend, the flow direction changes from a first direction to a second direction. A preset angle is formed between the first direction and the second direction, and the size of the preset angle is 30° to 150°.

[0034] Please refer to Figure 8 , Figure 8 This is a schematic diagram of the electrolyte flow direction provided in an embodiment of this application. Taking the electrolyte entering the second flow channel 113 as an example, it can be understood that in order for the electrolyte to enter the second flow channel 113 from the liquid flow hole 112 on the first surface, the flow direction of the electrolyte in the first liquid flow channel needs to be changed by a certain angle, and the angle of change of the flow direction is 30°~150°.

[0035] Specifically, the preset included angle is 90°. For example... Figure 8 As shown, the second liquid flow channel is parallel to the second flow channel 113. The flow direction of the electrolyte makes a 90° turn in the first liquid flow channel, so that the electrolyte enters the liquid flow hole 112 in a direction perpendicular to the second flow channel 113.

[0036] The first liquid flow channel includes a first sub-channel near the docking hole 1212 and a second sub-channel away from the docking hole 1212. The first and second sub-channels are connected by a bend, and the angle between the first and second sub-channels is a preset angle between the flow directions, i.e., 30°~150°. Furthermore, the length of the first sub-channel is shorter than the length of the second sub-channel, so that the electrolyte can enter the second flow channel 113 at a higher flow rate after changing the flow direction, reducing pressure loss during the electrolyte flow process.

[0037] Please refer to Figure 9 , Figure 9 This is a partially enlarged schematic diagram of the locking part provided in an embodiment of this application.

[0038] like Figure 9 As shown, in some embodiments, the docking portion 1211 includes a first docking portion 12111 and a second docking portion 12112, a docking hole 1212 is disposed in the first docking portion 12111, and a locking portion 12113 is disposed between the first docking portion 12111 and the second docking portion 12112. The first width of the locking portion 12113 on the side closer to the first docking portion 12111 is greater than the second width on the side closer to the second docking portion 12112.

[0039] Please continue reading Figure 9 From the first mating portion 12111 to the second mating portion 12112, the width of the locking portion 12113 gradually decreases. In some embodiments, the width of the first mating portion 12111 is also greater than the width of the second mating portion 12112. It is understood that the first recess 111 has a shape corresponding to the first mating portion 12111 to the second mating portion 12112. Therefore, the width of the first recess 111 also decreases in the direction away from the fluid flow hole 112. The opening width formed by the first recess 111 on the side of the first bipolar plate 11 is greater than the second width and less than the first width, which is insufficient to allow the fluid connector 12 to disengage from the side of the first bipolar plate 11.

[0040] Please refer to the following: Figure 3 , Figure 10 , Figure 10 This is a schematic diagram of a battery cell provided for another embodiment of this application. (See attached diagram.) Figure 3 , Figure 10 As shown, during battery stack assembly, the mating portion 1211 of the liquid circuit connector 12 is first inserted into the first recess 111, and then the battery cells with the liquid circuit connector 12 are stacked along the thickness direction to obtain the battery stack 100. Due to the presence of the locking portion 12113, after the battery stack 100 is assembled, the liquid circuit connector 12 will not detach from the side of the battery stack due to the pull-out force and torque of the external electrolyte pipe. Furthermore, friction is generated between the locking portion 12113 and the first bipolar plate 11, and the mechanical load from the external electrolyte pipe is absorbed by the liquid circuit connector 12, preventing the mechanical load from being transmitted to the first bipolar plate 11 and causing damage to the brittle graphite bipolar plate, thus improving the service life of the graphite bipolar plate.

[0041] In some embodiments, the material of the fluid connector includes at least one of the following: polypropylene, polyvinylidene fluoride, and polyetheretherketone.

[0042] Since the electrolyte in flow batteries is usually a corrosive acidic electrolyte, such as the vanadium redox flow battery electrolyte which is a sulfuric acid solution of vanadium ions, corrosion-resistant materials are used to make the liquid circuit connectors in order to avoid corrosion by the acidic solution. These materials include polypropylene (PP), polyvinylidene fluoride (PVDF), and polyether ether ketone (PEEK).

[0043] Please refer to Figure 11 , Figure 11 This is a physical diagram of a fluid circuit connector provided in one embodiment of this application. Figure 11 As shown, the liquid circuit connector is made of the above-mentioned material by injection molding. The process is mature and has a certain degree of transparency. The liquid inside can be directly seen through the liquid circuit connector, which facilitates the troubleshooting of the liquid circuit of the battery stack.

[0044] Please refer to Figure 12 , Figure 13 , Figure 12 A schematic diagram of the structure of the first bipolar plate and the second bipolar plate provided in an embodiment of this application; Figure 13 This is a schematic diagram of the structure of a first bipolar plate and a second bipolar plate provided in another embodiment of this application.

[0045] In some embodiments, the battery stack further includes a second bipolar plate 21, the third surface of the second bipolar plate 21 being adjacent to the first surface of the first bipolar plate 11, and a second recess 211 being provided on the third surface. The projections of the first recess 111 and the second recess 211 in the thickness direction at least partially overlap, and the first recess 111 and the second recess 211 form a cavity for accommodating the liquid circuit connector 12. When the mating portion 1211 is embedded in the first recess 111, at least a portion of the mating portion 1211 is exposed on the first surface in the thickness direction, and the portion of the mating portion 1211 exposed on the first surface is embedded in the second recess 211.

[0046] Please continue to refer to Figure 8 , Figure 10 When the liquid connector 12 is mounted on the first bipolar plate 11, at least a portion of the liquid connector 12 in the thickness direction is exposed on the first surface of the first bipolar plate 11.

[0047] To avoid the increase in thickness of the battery stack caused by the liquid circuit connector 12, such as Figure 12 , Figure 13 As shown, in the battery stack 100, when the first bipolar plate 11 and the second bipolar plate 21 are stacked, the first recess 111 on the first bipolar plate 11 and the second recess 211 on the second bipolar plate 21 form a chamber that can accommodate the liquid circuit connector 12. Figure 10 and Figure 11 These are the first bipolar plate 11 and the second bipolar plate 21 as observed from different directions, specifically, Figure 10 The first bipolar plate 11 and the second bipolar plate 21 are viewed from above. Figure 11 The first bipolar plate 11 and the second bipolar plate 21 are seen from above.

[0048] Understandably, the sum of the heights of the first recess 111 and the second recess 211 corresponds to the height of the mating portion 1211 of the liquid connector 12. In other words, the height of the cavity formed by the first recess 111 and the second recess 211 is slightly greater than the height of the mating portion 1211, so that the height of the battery stack will not increase when the liquid connector 12 is installed on the first bipolar plate 11.

[0049] In some embodiments, a first bipolar plate 11 and a second bipolar plate 21 are alternately arranged in a battery stack 100. The second bipolar plate 21 has a third surface and a fourth surface opposite to each other. A second recess 211 is provided on the second surface of the first bipolar plate 11. The projections of the second recess 211 and the first recess 111 in the thickness direction do not overlap. The second surface of the first bipolar plate 11 is adjacent to the fourth surface of the second bipolar plate 21. A first recess 111 is provided on the fourth surface of the second bipolar plate 21. The second recess 211 on the second surface and the first recess 111 on the fourth surface form the cavity.

[0050] Please continue to refer to Figure 10 , Figure 11 The first bipolar plate 11 has a first recess 111 and a second recess 211 on different surfaces, wherein the first recess 111 is used to mate with the liquid connector 12 to allow the electrolyte to enter and exit the second flow channel 113, and the second recess 211 is used to accommodate the liquid connector 12 of the adjacent second bipolar plate 21.

[0051] Understandably, the first bipolar plate 11 may be provided with four first recesses 111, which are respectively connected to liquid circuit connectors 12 for the inlet and outlet of the anode electrolyte and the inlet and outlet of the cathode electrolyte; similarly, the first bipolar plate may be provided with four second recesses 211, which are respectively used to accommodate the four liquid circuit connectors 12 of the adjacent second bipolar plate 21.

[0052] Correspondingly, on the third surface of the second bipolar plate 21 adjacent to the first bipolar plate, a second recess 211 is provided at a position corresponding to the first recess 111 on the first bipolar plate 11, for forming a chamber with the first recess 111 on the first bipolar plate 11; on the fourth surface of the second bipolar plate 21 opposite to the first bipolar plate, a second recess 111 is provided at a position corresponding to the second recess 211 on the first bipolar plate 11, for mating with the fluid connector 12. It can be understood that "corresponding" here refers to the position where the projections in the thickness direction coincide.

[0053] In some embodiments, end plates are provided on opposite sides of the battery stack 100 in the thickness direction, the end plates being used to provide sealing force for fixing the plurality of battery cells and fixing the liquid circuit connector to the bipolar plate.

[0054] Please continue to refer to Figure 7 The top and bottom (not shown) of the battery stack 100 are respectively provided with end plates 31. In related technologies, the end plates 31 are used to provide a sealing force for fixing the battery cells. In the embodiments of this application, since the direction of the sealing force for fixing the battery cells and the direction of the sealing force for fixing the liquid circuit connector are the same, both being the thickness direction of the battery cells, the end plates 31 are used not only for fixing the battery cells but also for fixing the liquid circuit connector 12. That is, the end plates 31 also have the function of fixing the liquid circuit connector 12 to the first bipolar plate 11 or the second bipolar plate 21, and no additional fastening operation is required for the liquid circuit connector 12 during the assembly of the battery stack 100.

[0055] In some embodiments, the first connector 121 and the second connector 122 are detachably connected.

[0056] Please refer to Figure 14 , Figure 14 This is a schematic diagram of the structure of a liquid circuit connector provided in an embodiment of this application.

[0057] like Figure 14 As shown, the first connector 121 and the second connector 122 of the liquid circuit connector 12 are detachably connected. The second connector 122, which is connected to an external electrolyte pipeline, can be detached from the first bipolar plate 11, which is beneficial for the maintenance and repair of the liquid circuit.

[0058] Of course, it is not limited to this. The first connector 121 and the second connector 122 can also be integrally formed, which is not limited here.

[0059] Please continue to refer to Figures 3-14 This application embodiment also provides a liquid circuit connector 12, which includes a first connector 121 and a second connector 122. The first connector 121 includes a mating portion 1211, and a first liquid flow channel is provided in the first connector 121. The first liquid flow channel has a mating hole 1212 formed in the mating portion 1211. The mating hole 1212 is used to mate with a liquid flow hole on the first surface of a bipolar plate. The plane on which the first surface is located is perpendicular to the thickness direction of the bipolar plate. The second connector 122 is used to connect to an external electrolyte pipeline. The second connector 122 has a second liquid flow channel, and the second liquid flow channel is connected to the first liquid flow channel. The electrolyte in the external electrolyte pipeline enters the second flow channel on the second surface of the bipolar plate sequentially through the second flow channel, the first flow channel, the docking hole 1212, and the flow hole of the liquid connector 12. Alternatively, the electrolyte in the second flow channel enters the external electrolyte pipeline sequentially through the flow hole, the docking hole 1212 of the liquid connector 12, the first flow channel, and the second flow channel.

[0060] It is understood that the liquid circuit connector 12 provided in this application embodiment can be used in the battery stack described in any embodiment of this application. The specific structure of the liquid circuit connector 12 can also be referred to the description of the liquid circuit connector in the battery stack described in any embodiment of this application, and will not be repeated here.

[0061] It should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application.

[0062] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0063] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0064] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “compose” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0065] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application.

Claims

1. A flow battery stack, characterized in that, It includes multiple battery cells stacked along the thickness direction, the battery cells comprising: A first bipolar plate, comprising a first surface and a second surface opposite to each other, wherein the plane containing the first surface and the second surface is perpendicular to the thickness direction; wherein a first recess is provided on the first surface, and a second flow channel is provided on the second surface, and the first recess on the first surface is connected to the second flow channel on the second surface through a liquid flow hole. A liquid circuit connector includes a first connector and a second connector. The mating portion of the first connector is embedded in a first recessed portion, and the first recessed portion and the mating portion have corresponding shapes. A first liquid flow channel is provided in the first connector, and the first liquid flow channel forms a mating hole in the mating portion for corresponding to the liquid flow orifice. The second connector is used to connect to an external electrolyte pipeline. A second liquid flow channel is provided in the second connector, and the second liquid flow channel is connected to the first liquid flow channel. The electrolyte in the external electrolyte pipeline enters the second flow channel of the second surface sequentially through the second flow channel, the first flow channel, the docking hole, and the flow hole of the liquid connector; or, the electrolyte in the second flow channel enters the external electrolyte pipeline sequentially through the flow hole, the docking hole of the liquid connector, the first flow channel, and the second flow channel.

2. The battery stack according to claim 1, characterized in that, A sealing groove is provided on the periphery of the docking hole, and the sealing groove is filled with a sealing element.

3. The battery stack according to claim 1, characterized in that, The first liquid flow channel is provided with a bend. When the electrolyte flows in the first liquid flow channel to the bend, the flow direction changes from a first direction to a second direction. A preset angle is formed between the first direction and the second direction, and the size of the preset angle is 30°~150°.

4. The battery stack according to claim 1, characterized in that, The docking portion includes a first docking portion and a second docking portion. The docking hole is disposed on the first docking portion. A locking portion is disposed between the first docking portion and the second docking portion. The first width of the locking portion on the side closer to the first docking portion is greater than the second width on the side closer to the second docking portion.

5. The battery stack according to claim 1, characterized in that, The material of the fluid circuit connector includes at least one of the following: polypropylene, polyvinylidene fluoride, and polyetheretherketone.

6. The battery stack according to claim 1, characterized in that, The battery stack further includes a second bipolar plate, the third surface of which is adjacent to the first surface of the first bipolar plate, and a second recess is provided on the third surface. The projections of the first recess and the second recess in the thickness direction at least partially overlap, and the first recess and the second recess form a cavity for accommodating the liquid circuit connector. When the mating portion is embedded in the first recess, at least a portion of the mating portion is exposed on the first surface in the thickness direction, and the portion of the mating portion exposed on the first surface is embedded in the second recess. The sum of the heights of the first recess and the second recess corresponds to the height of the mating portion, so that the height of the battery stack does not increase when the liquid circuit connector is installed on the first bipolar plate.

7. The battery stack according to claim 6, characterized in that, The first bipolar plate and the second bipolar plate are alternately arranged in the battery stack. The second bipolar plate has a third surface and a fourth surface opposite each other. The second surface of the first bipolar plate is provided with a second recess. The projection of the second recess and the first recess in the thickness direction do not overlap. The second surface of the first bipolar plate is adjacent to the fourth surface of the second bipolar plate. The fourth surface of the second bipolar plate is provided with the first recess. The second recess of the second surface and the first recess of the fourth surface form the cavity.

8. The battery stack according to any one of claims 1-7, characterized in that, End plates are respectively provided on opposite sides of the battery stack in the thickness direction. The end plates are used to provide sealing force for fixing multiple battery cells and fixing the liquid circuit connector to the bipolar plate.

9. The battery stack according to any one of claims 1-7, characterized in that, The first connector and the second connector are detachably connected.

10. A fluid circuit connector, characterized in that, The liquid circuit connector includes a first connector and a second connector. The first connector includes a mating portion and a first liquid flow channel is provided within the first connector. The first liquid flow channel forms a mating hole in the mating portion. The mating hole is used to mate with a liquid flow hole on the first surface of the bipolar plate. The plane containing the first surface is perpendicular to the thickness direction of the bipolar plate. The second connector is used to connect to an external electrolyte pipeline. The second connector includes a second liquid flow channel, which is connected to the first liquid flow channel. The electrolyte in the external electrolyte pipeline enters the second flow channel on the second surface of the bipolar plate sequentially through the second flow channel, the first flow channel, the docking hole, and the flow hole of the liquid circuit connector; or, the electrolyte in the second flow channel enters the external electrolyte pipeline sequentially through the flow hole, the docking hole of the liquid circuit connector, the first flow channel, and the second flow channel.

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