Bipolar plate for flow battery, flow battery and battery stack

Abstract

The present invention relates to the technical field of flow batteries, and particularly to a bipolar plate for a flow battery, a flow battery, and a battery stack. The bipolar plate is provided with a flow channel area, and the flow channel area includes a liquid inlet, a liquid supply distribution flow channel, and a liquid outlet that are sequentially connected. The flow channel area further includes a plurality of shunt modules that are spaced apart from each other. The liquid supply distribution flow channel is formed between the shunt modules and the edge of the flow channel area and between adjacent shunt modules, which can first shunt the liquid flow entering the bipolar plate from the liquid inlet and then converge it, and finally converge and flow out from the liquid outlet. The bipolar plate for a flow battery provided by the present invention has a liquid supply distribution flow channel with a specific structure, and this liquid supply distribution flow channel exhibits the characteristics of multi-channel multi-stage collection and redistribution, which is beneficial to the mass transfer uniformity of the electrolyte concentration. At the same time, the flow resistance is significantly reduced, the pressure drop is at a low level, and it is beneficial to improve the pump efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of flow batteries, and particularly relates to a bipolar plate for a flow battery, a flow battery, and a battery stack. Background Art

[0002] A flow battery is an electrochemical energy storage technology that utilizes the oxidation-reduction reaction of active substances in the liquid phases of the positive and negative electrodes during the charge and discharge processes to achieve energy storage and release, including technologies such as all-vanadium flow batteries, iron-chromium flow batteries, and zinc-bromine flow batteries. The single cell of a flow battery mainly consists of a bipolar plate, an electrode, a membrane, and a current collector plate. Among them, the bipolar plate not only functions as a conductor but also functions as an electrolyte distributor.

[0003] Traditional bipolar plate flow field structures include interdigitated and serpentine. The interdigitated flow field has problems of large flow resistance and uneven electrolyte distribution; compared with the interdigitated flow field, the serpentine flow field has improved flow resistance, but the electrolyte concentration continuously decreases along the serpentine flow channel, and the electrolyte concentration is significantly uneven. The flow field structure of the bipolar plate has a great influence on the uniformity of the electrolyte. The more uniform the electrolyte, the more uniform the oxidation-reduction reaction of the electrolyte on the electrode, thereby avoiding problems such as intense local reactions and overheating of the reaction. In addition, the flow field structure of the bipolar plate also affects the flow resistance of the electrolyte in the battery stack, thereby affecting the pump efficiency. How to improve the uniformity of electrolyte mass transfer and pump efficiency in a flow battery is of great significance for improving the stability and lifespan of the flow battery.

[0004] CN108987763A discloses a bipolar plate for a flow battery with a hierarchical interdigitated flow field. The liquid supply distribution channels and the liquid discharge distribution channels of the bipolar plate are respectively provided with a plurality of branch channels, and the final-stage liquid supply branch channels and the final-stage liquid discharge branch channels are arranged in an interdigitated manner and are not connected to each other, so as to force the electrolyte to be supplied from the final-stage liquid supply branch channels into the porous electrode and then collected and discharged from the final-stage liquid discharge branch channels. The hierarchical interdigitated flow field can flexibly and independently design the geometric structure of each stage of the flow channel. While keeping the size of the final-stage flow channel similar to the traditional structure, the cross-sectional area of the flow channels at all levels before the final-stage flow channel is increased, which can further enhance mass transfer and reduce pump power loss, and improve the battery voltage efficiency and the battery system efficiency. This patent application can improve the mass transfer ability by setting a secondary interdigitated flow field on the basis of the interdigitated flow field, and can reduce the pump power loss to a certain extent, but this patent application does not reflect the performance of mass transfer uniformity. Summary of the Invention

[0005] The object of the present invention is to overcome the problem that the electrolyte mass transfer performance of the existing bipolar plate flow field in a flow battery needs to be further improved, and to provide a bipolar plate for a flow battery, a flow battery, and a battery stack. The bipolar plate for the flow battery is beneficial to the mass transfer uniformity of the electrolyte concentration, and at the same time, the flow resistance is at a relatively low level, which can improve the pump efficiency.

[0006] To achieve the above object, a first aspect of the present invention provides a bipolar plate for a flow battery. The bipolar plate is provided with a flow channel region, and the flow channel region includes a liquid inlet, a liquid supply distribution channel, and a liquid outlet that are connected in sequence. The flow channel region further includes a plurality of shunt modules arranged at intervals. The liquid supply distribution channel is formed between the shunt modules and the edge of the flow channel region and between adjacent shunt modules, which can first shunt the liquid flow entering the bipolar plate from the liquid inlet and then converge it, and finally converge and flow out from the liquid outlet.

[0007] A second aspect of the present invention provides a flow battery, which includes a positive electrode, a negative electrode, and a separator existing between the positive electrode and the negative electrode, and also includes a first bipolar plate adjacent to the positive electrode and a second bipolar plate adjacent to the negative electrode;

[0008] The first bipolar plate and the second bipolar plate are each independently the bipolar plate described in the first aspect above.

[0009] A third aspect of the present invention provides a battery stack, which includes a plurality of the flow batteries described in the second aspect above.

[0010] Through the above technical solutions, the bipolar plate for a flow battery provided by the present invention has a liquid supply distribution channel with a specific structure. This liquid supply distribution channel features multi-channel multi-stage convergence and redistribution, which is beneficial to the mass transfer uniformity of the electrolyte concentration. At the same time, compared with the existing bipolar plates, the flow resistance is significantly reduced, and the pressure drop is at a relatively low level within the allowable range (generally, the pressure drop can be within 0.1 - 20 kPa), which is beneficial to improving the pump efficiency.

[0011] Furthermore, preferably, the mass transfer uniformity of the electrolyte concentration of the shunt module with a specific structure is better. At a voltage of 1.22 V, the current density distributions in the four regions are 64.5, 64.4, 64.5, and 64.2 mA / cm 2 , while the current density distributions in the four regions of the existing serpentine flow channel under the same conditions are 56.3, 64.3, 64.5, and 64.9 mA / cm 2 . It can be seen that the uniformity of the current density distribution of the preferred solution of the present invention is significantly higher than that of the serpentine flow channel.

[0012] Since the flow battery provided by the present invention adopts the specific bipolar plate of the present invention, the electrolyte shows the characteristics of convergence and then redistribution in each flow channel, making the distribution of the electrolyte concentration in the flow field more uniform.

[0013] The flow battery of the present invention is used in a battery stack, which can solve the problem of local overheating of the redox reaction on the electrode caused by uneven distribution of the electrolyte in the battery stack, and is beneficial to improving the stability and lifespan of the battery stack. Description of the Drawings

[0014] Figure 1 is a schematic structural view of a specific embodiment of the bipolar plate for a flow battery of the present invention;

[0015] Figure 2 is Figure 1 an enlarged view of part A in

[0016] Figure 3 is a curve showing the change of the pressure drop of the flow battery in Example 1 and Comparative Example 1 of the present invention with the flow rate of the electrolyte.

[0017] Figure 4 is a schematic structural view of an existing bipolar plate with a serpentine flow channel.

[0018] Description of the Reference Numerals

[0019] 1 - Liquid inlet 2 - Liquid outlet 3 - Edge

[0020] 4 - First flow splitting module 5 - Second flow splitting module Detailed Embodiments

[0021] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "vertical", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings, and 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 thus cannot be understood as a limitation to the present invention.

[0023] The first aspect of the present invention provides a bipolar plate for a flow battery, as shown in Figure 1 and Figure 2 The bipolar plate is provided with a flow channel area, and the flow channel area includes a liquid inlet 1, a liquid supply distribution channel and a liquid outlet 2 that are connected in sequence. The flow channel area further includes a plurality of flow splitting modules that are arranged at intervals. The flow splitting modules and the edge 3 of the flow channel area and between adjacent flow splitting modules form the liquid supply distribution channel, which can first split the liquid flow entering the bipolar plate from the liquid inlet 1 and then converge it, and finally converge and flow out from the liquid outlet 2.

[0024] It is understandable that the flow channel region refers to the region on the bipolar plate through which the electrolyte can flow. Generally, the flow channel region is arranged at the central position on both side surfaces of the bipolar plate. The overall shape of the flow channel region can be a conventional square or rectangle (such as Figure 1 shown), or other special-shaped structures (such as a circle, etc.), preferably a conventional square or rectangle.

[0025] In the present invention, the edge 3 refers to the contour line of the flow channel region, that is, Figure 1 the contour line of the front view shown.

[0026] In the present invention, it is understandable that the flow splitting module is formed by arranging (such as by engraving) the liquid supply distribution flow channels on the bipolar plate, and the flow splitting module is also called a ridge.

[0027] With the bipolar plate having the flow channel region with the specific structure as described above, the present invention can first split the liquid flow of the electrolyte and then converge it, repeating the process of splitting and then converging the liquid flow many times, and finally converging and flowing out, thereby realizing the mass transfer uniformity of the electrolyte concentration. At the same time, the flow resistance is significantly reduced, the pressure drop is at a relatively low level, and the pump efficiency can be improved.

[0028] In the present invention, it is understandable that the present invention does not particularly limit the setting positions of the liquid inlet 1 and the liquid outlet 2. In order to reduce the dead angle of the electrolyte, preferably, the electrolyte inlet and the electrolyte outlet are arranged diagonally on the bipolar plate (it is understandable that it can also be arranged such that the liquid inlet 1 is located at Figure 1 the lower right corner, and the liquid outlet 2 is located at Figure 1 the upper left corner).

[0029] According to the present invention, preferably, the plurality of flow splitting modules are each independently of a regular or irregular shape, as long as it is beneficial to improving the mass transfer uniformity of the electrolyte concentration, reducing the flow resistance, and improving the pump efficiency.

[0030] More preferably, the plurality of flow splitting modules are each independently of a regular shape. The regular shape includes but is not limited to a quadrilateral (such as a rectangle, a square, a trapezoid, and a quadrilateral with at least one side being an arc, preferably a quadrilateral with all four sides being concave arcs), an ellipse (it is understandable that, for example, Figure 1 the petal shape shown) or a circle. When the regular shape is a square, it indicates that the height and width of the flow splitting module are the same.

[0031] According to the present invention, preferably, the plurality of flow splitting modules have the same shape, and the shape is one of a quadrilateral, an ellipse, and a circle. Under this preferred scheme, it is more beneficial to improving the mass transfer uniformity of the electrolyte concentration, reducing the flow resistance, and improving the pump efficiency.

[0032] According to the present invention, the arrangement range of the plurality of flow splitting modules is relatively wide. Preferably, in the flow channel region, the plurality of flow splitting modules are regularly arranged. The regular arrangement is, for example, an array arrangement.

[0033] According to the present invention, preferably, in the horizontal direction and / or the vertical direction along the flow channel region, the center distance D between two adjacent flow splitting modules is 4 - 50 mm. More preferably, D is 5 - 10 mm. By adopting this preferred solution, the mass transfer uniformity of the electrolyte concentration can be further improved.

[0034] In the present invention, the center distance D between two adjacent flow splitting modules refers to the distance between the geometric centers of the flow splitting modules of two adjacent repeating units.

[0035] In a preferred embodiment of the present invention, the flow splitting module includes a first flow splitting module 4. It can be understood that a plurality of the first flow splitting modules 4 are preferably regularly arranged, and a liquid supply distribution flow channel is formed between the plurality of the first flow splitting modules 4 and between the first flow splitting module 4 and the edge 3 of the flow channel region.

[0036] Further preferably, the flow splitting module further includes a second flow splitting module 5. Under this preferred solution, a liquid supply distribution flow channel is also formed between the second flow splitting module 5 and the first flow splitting module 4, which is beneficial to forming more branch flow channels.

[0037] The shape of the second flow splitting module 5 may be the same as or different from the shape of the first flow splitting module 4; the latter is preferred.

[0038] In the present invention, preferably, in the horizontal direction and / or the vertical direction along the flow channel region, the second flow splitting module 5 and the first flow splitting module 4 are arranged at intervals. It can be understood that the center distance D refers to, as Figure 1 shown, in the horizontal direction or the vertical direction along the flow channel region, the geometric center distance (denoted as D1) between two adjacent second flow splitting modules 5, or the geometric center distance (denoted as D2) between two adjacent first flow splitting modules 4. D1 and D2 may be the same or different, and the same is preferred.

[0039] More preferably, in the flow channel region, one second flow splitting module 5 is arranged in each of the upper, lower, left, and right directions of each first flow splitting module 4. Under this preferred solution, a plurality of liquid supply distribution flow channels can be formed, so as to divide a liquid flow upstream into at least 4 liquid flows, further promoting the mass transfer uniformity of the electrolyte, improving the pump efficiency, and keeping the pressure drop at a relatively low level.

[0040] In the present invention, it can be understood that the second flow splitting module 5 may be in a regular or irregular shape, and a regular shape is preferred.

[0041] More preferably, as Figure 1 and Figure 2 shown, the first flow splitting module 4 is quadrilateral, and the second flow splitting module 5 is oval.

[0042] In the present invention, preferably, the edge 3 is in a regular or irregular shape. More preferably, the edge 3 is in a regular shape. The regular shape is, for example, a straight line type or a curve type (such as Figure 1 the arc shape shown).

[0043] According to the present invention, preferably, the depth and the shortest width of the liquid supply distribution channel are each independently 0.5 - 5 mm.

[0044] According to the present invention, the height of the flow splitting module has a relatively wide optional range, as long as it is conducive to the uniform mass transfer of the electrolyte and the pressure drop is at a relatively low level. Preferably, the height of multiple flow splitting modules is the same as the depth of the liquid supply distribution channel.

[0045] According to the present invention, preferably, the depths of the liquid inlet 1 and the liquid outlet 2 are each independently 2 - 15 mm.

[0046] According to the present invention, preferably, the widths of the liquid inlet 1 and the liquid outlet 2 are each independently 2 - 15 mm.

[0047] In the present invention, the flow channel width and the flow channel depth of the liquid inlet 1 and the liquid outlet 2 respectively refer to the width perpendicular to the liquid flow direction and the depth parallel to the liquid flow direction.

[0048] According to the present invention, preferably, the liquid inlet 1 and the liquid outlet 2 are circular. Under this preferred scheme, the inner diameters of the liquid inlet 1 and the liquid outlet 2 are the flow channel widths.

[0049] In a second aspect of the present invention, a flow battery is provided. The flow battery includes a positive electrode, a negative electrode, and a separator existing between the positive electrode and the negative electrode, and further includes a first bipolar plate adjacent to the positive electrode and a second bipolar plate adjacent to the negative electrode;

[0050] The first bipolar plate and the second bipolar plate are each independently the bipolar plate described in the first aspect above.

[0051] In the present invention, it can be understood that the bipolar plate is located on the side of the positive electrode or the negative electrode away from the separator.

[0052] In the present invention, there is no restriction on the materials of the positive electrode, the negative electrode, the bipolar plate, and the separator, and any existing corresponding materials in the prior art in this field can be used, and they can all be applied to the present invention. For example, the separator can be any separator commonly used in this field, and the present invention has no special limitation on it, as long as it can allow the passage of ions connecting the positive and negative electrodes of the battery (preventing the passage of other ions and solvents). The connecting ions include but are not limited to H + , Na + , K + , Li + , OH - plasma ions.

[0053] According to the present invention, preferably, the depth and the shortest width of the liquid supply distribution flow channel in the first bipolar plate are each independently 0.5 - 3 mm.

[0054] According to the present invention, preferably, the depth and the shortest width of the liquid supply distribution flow channel in the second bipolar plate are each independently 0.5 - 5 mm.

[0055] Specifically, according to the present invention, the flow battery further includes a positive electrode electrolyte and a negative electrode electrolyte. The present invention has a relatively wide selection range for the positive electrode electrolyte and the negative electrode electrolyte, and appropriate selection can be made according to the specific type of flow battery. In the present invention, it can be understood that the positive electrode includes a positive electrode, a first bipolar plate, and a positive electrode electrolyte, and the negative electrode includes a negative electrode, a second bipolar plate, and a negative electrode electrolyte. Preferably, the flow battery is a vanadium redox flow battery. Preferably, the positive electrode electrolyte causes a reaction including the mutual conversion of pentavalent vanadium ions and tetravalent vanadium ions at the positive electrode; preferably, the negative electrode electrolyte causes a reaction including the mutual conversion of trivalent vanadium ions and divalent vanadium ions at the negative electrode. For example, the positive electrode electrolyte can be a solution of V(IV)+V(V)+sulfuric acid, where the total concentration of V(IV+V) is 1 - 2 mol / L and the concentration of sulfuric acid is 1 - 5 mol / L; the negative electrode electrolyte can be a solution of V(II)+V(III)+sulfuric acid, where the total concentration of V(II+III) can be 1 - 2 mol / L and the concentration of sulfuric acid can be 1 - 5 mol / L. Among them, the positive electrode electrolyte or the negative electrode electrolyte also contains an anion corresponding to the V ion in the corresponding valence state, and the present invention has no limitation on this anion, as long as it satisfies the solution of the above corresponding V ion, its concentration, and the specific concentration of sulfuric acid.

[0056] The third aspect of the present invention provides a battery stack, and the battery stack includes a plurality of the flow batteries described in the second aspect above.

[0057] The present invention has no limitation on the connection mode of the multiple flow batteries, and series connection and / or parallel connection can be performed (it can be understood that when it is series connection and parallel connection, it means that after partial series connection, it is then connected in parallel with other parts), and those skilled in the art can make corresponding settings according to the actual situation.

[0058] The present invention will be described in detail below through embodiments.

[0059] Embodiment 1

[0060] (1) Set the bipolar plate

[0061] As Figure 1 shown, a flow channel area is set at the center position of the bipolar plate. The overall shape of the flow channel area is a square (side length is 50 mm), and its edge 3 is an arc protruding outward with regular arrangement.

[0062] The flow channel area includes a liquid inlet 1, a liquid supply distribution channel, a liquid outlet 2, and a plurality of first shunt modules 4 (with the same size, all being squares and having arcs concave inward on all four sides) and a plurality of second shunt modules 5 (with the same size, all being petal-shaped, that is, oval) that are connected in sequence. The first shunt modules 4 are arranged in a 9×9 pattern within the flow channel area. The arc repeating units of the edge 3 of the flow channel area correspond one by one to the first shunt modules 4. Liquid supply distribution channels are formed between adjacent first shunt modules 4 and second shunt modules 5, between adjacent first shunt modules 4, and between the second shunt modules 5 and the edge 3 of the flow channel area. The height of the first shunt modules 4 and the second shunt modules 5 is the same as the depth of the liquid supply distribution channels.

[0063] In the horizontal and vertical directions of the flow channel area, the first shunt modules 4 and the second shunt modules 5 are arranged at intervals, and one second shunt module 5 is respectively arranged at the centers of the upper, lower, left, and right four directions of each first shunt module 4. In the horizontal and vertical directions along the flow channel area, the center distance D between adjacent two first shunt modules 4 and between adjacent two second shunt modules 5 is 5.6 mm.

[0064] Circular liquid inlet 1 and liquid outlet 2 are provided on the bipolar plate. The flow channel widths of the liquid inlet 1 and the liquid outlet 2 are both 5 mm, and the flow channel depths of the liquid inlet 1 and the liquid outlet 2 are both 15 mm.

[0065] (2) Flow battery

[0066] The flow battery includes a separator 1 (a perfluorosulfonic acid separator, commercially purchased from Chemours Company, a product with the brand name Nafion115), a positive electrode provided on one side of the separator, and a negative electrode provided on the other side. Both the positive electrode and the negative electrode are carbon papers, commercially purchased from SGL, with a size of 50 mm×50 mm×1 mm.

[0067] The flow battery further includes a first bipolar plate adjacent to the positive electrode and a second bipolar plate adjacent to the negative electrode; both the first bipolar plate and the second bipolar plate are the above-mentioned bipolar plates. Among them, the depth of the liquid supply distribution channel in the first bipolar plate is 1 mm, and the shortest width is 1.2 mm; the depth of the liquid supply distribution channel in the second bipolar plate is 1 mm, and the shortest width is 1.2 mm. The positive electrode electrolyte is a solution of [V(IV)+V(V)] of 1 mol L -1 + 5 mol L -1 H2SO4, and the negative electrode electrolyte is a solution of [V(II)+V(III)] of 1 molL -1 + 5 mol L -1 H2SO4 solution.

[0068] The flow channel area on the bipolar plate is divided into four square or rectangular areas as a whole (in the direction from the liquid inlet to the liquid outlet, they are Area 1 (upper left), Area 2 (lower left), Area 3 (lower right), and Area 4 (upper right) in sequence). The current in these four areas is measured, and then the current density distribution is calculated, where the current density = current / measured reaction area. The current is measured by an electrochemical workstation, and 1 / 4 carbon paper (from the same source) + 3 / 4 polytetrafluoroethylene sheet is used to cover the flow channel area (that is, the current density of a measured area where the test electrode is located). At a voltage of 1.22 V, the test results are listed in Table 1.

[0069] The flow resistance (i.e., the flow resistance pressure drop) is obtained by CFD simulation. The test results are as Figure 3 shown, and the curve of its pressure drop changing with the electrolyte flow rate is listed in Table 1.

[0070] Comparative Example 1

[0071] Assemble the flow battery according to Example 1, except that the flow channel structure on the bipolar plate is different. Specifically, as Figure 4 shown, a serpentine flow channel with a parallel double-flow channel structure (i.e., a double channel) is arranged at the center position of the bipolar plate. Its overall size and shape are the same as those of the flow channel area in Example 1 (i.e., a square). The distance between the parallel double-flow channel structures is 2 mm; the depth of the serpentine flow channel is 1 mm, the flow channel width is 1.2 mm, and the width of the ridge (i.e., the raised part forming the serpentine flow channel) is 1.2 mm. The test results are listed in Table 1.

[0072] Example 2

[0073] Assemble the flow battery according to Example 1, except that the center distance D between two adjacent first shunt modules 4 and between two adjacent second shunt modules 5 is 7.1 mm. The test results are listed in Table 1.

[0074] Example 3

[0075] Assemble the flow battery according to Example 1, except that the center distance D between two adjacent first shunt modules 4 and between two adjacent second shunt modules 5 is 10 mm. The test results are listed in Table 1.

[0076] Example 4

[0077] Assemble the flow battery according to Example 1, except that a plurality of the first shunt modules 4 are arranged in the flow channel region, and the second shunt modules 5 are not arranged, and the others are the same as in Example 1. The test results are listed in Table 1.

[0078] Example 5

[0079] Assemble the flow battery according to Example 1, except that the second shunt modules 5 are arranged in the flow channel region, and the first shunt modules 4 are not arranged, and the others are the same as in Example 1. The test results are listed in Table 1.

[0080] Table 1

[0081]

[0082]

[0083] Among them, the standard deviation is calculated based on the STDEVP function, and the pressure drop is measured at an electrolyte flow rate of 50 mL / min.

[0084] From Table 1 and Figure 3 the results, it can be seen that the embodiments using the bipolar plate provided by the present invention have significantly better mass transfer uniformity of the electrolyte concentration on the basis of ensuring that the pressure drop is at a relatively low level (the pressure drop is 0.1 - 0.55 kPa), and at the same time, the average current density is higher, showing better electrochemical performance. By comparing Example 1 with Example 4 and Example 5, it can be known that adopting the solution of the preferred Example 1 of the present invention has a larger average current density and a smaller standard deviation, indicating that this preferred solution can make the mass transfer uniformity of the electrolyte concentration better and the electrochemical performance more excellent on the basis of ensuring that the pressure drop is within the allowable range.

[0085] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A bipolar plate for a flow battery, the bipolar plate being provided with a flow channel area, the flow channel area including a liquid inlet (1), a liquid supply distribution flow channel and a liquid outlet (2) that are sequentially connected, characterized in that, The flow channel region further includes a plurality of shunt modules arranged at intervals from each other. A liquid supply distribution flow channel is formed between the shunt modules and the edge (3) of the flow channel region and between adjacent shunt modules, which can first shunt the liquid flow entering the bipolar plate from the liquid inlet (1) and then converge it, and finally converge and flow out from the liquid outlet (2); wherein, within the flow channel region, the plurality of shunt modules are arranged regularly; In the horizontal direction and / or the vertical direction along the flow channel region, the center distance D between two adjacent shunt modules is 4-50 mm; The shunt module includes a first shunt module (4) and a second shunt module (5); in the horizontal direction and / or the vertical direction along the flow channel region, the second shunt module (5) is arranged at intervals from the first shunt module (4); within the flow channel region, one second shunt module (5) is arranged in each of the upper, lower, left, and right directions of each first shunt module (4); The first shunt module (4) and the second shunt module (5) are each independently of a regular shape; the first shunt module (4) is a quadrilateral; the second shunt module (5) is an ellipse; The depth and the shortest width of the liquid supply distribution flow channel are each independently 0.5-5 mm; the height of the plurality of shunt modules is the same as the depth of the liquid supply distribution flow channel; The flow channel depths of the liquid inlet (1) and the liquid outlet (2) are each independently 2-15 mm; The flow channel widths of the liquid inlet (1) and the liquid outlet (2) are each independently 2-15 mm.

2. The bipolar plate for a flow battery according to claim 1, characterized in that, In the horizontal direction and / or the vertical direction along the flow channel region, the center distance D between two adjacent shunt modules is 5-10 mm.

3. The bipolar plate for a flow battery according to claim 1 or 2, characterized in that, The edge (3) is of a regular or irregular shape.

4. The bipolar plate for a flow battery according to claim 3, characterized in that, The edge (3) is of a regular shape.

5. The bipolar plate for a flow battery according to any one of claims 1, 2, and 4, characterized in that The liquid inlet (1) and the liquid outlet (2) are circular.

6. The bipolar plate for a flow battery according to claim 3, wherein, The liquid inlet (1) and the liquid outlet (2) are circular.

7. A flow battery, which includes a positive electrode, a negative electrode, and a separator existing between the positive electrode and the negative electrode, and further includes a first bipolar plate adjacent to the positive electrode and a second bipolar plate adjacent to the negative electrode; The first bipolar plate and the second bipolar plate are each independently the bipolar plate according to any one of claims 1-6.

8. The flow battery according to claim 7, wherein, The depth and the shortest width of the liquid supply distribution flow channel in the first bipolar plate are each independently 0.5-3 mm; And / or, the depth and the shortest width of the liquid supply distribution flow channel in the second bipolar plate are each independently 0.5-5 mm.

9. A battery stack, which includes a plurality of flow batteries according to claim 7 or 8.

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