Universal electrode frame suitable for various flow battery stacks and flow battery stack

Abstract

The invention belongs to the technical field of flow batteries, and discloses a universal electrode frame suitable for various flow battery stacks and a flow battery stack.The universal electrode frame is composed of a liquid inlet, a liquid outlet, a liquid inlet main flow channel, liquid inlet branch flow channels at all stages, a reaction area, a liquid outlet main flow channel and liquid outlet branch flow channels at all stages; the reaction area is used for placing a reaction electrode and a runner plate, the liquid inlet is communicated with the reaction area through the liquid inlet main runner and each stage of liquid inlet sub-runner, the reaction area is communicated with the liquid outlet through the liquid outlet main runner and each stage of liquid outlet sub-runner, and the runner plates of each stage of liquid inlet sub-runner and each stage of liquid outlet sub-runner are movably connected with the reaction area; and each stage of liquid inlet sub-runner and each stage of liquid outlet sub-runner are formed by combining changes of shapes, positions, sizes and numbers of the supporting strips. Different runner plates and porous electrodes can be matched to form an optimal flow field structure, so that electrolyte distribution is optimized, concentration polarization in a single section and between different sections is reduced, the voltage efficiency is improved, and the energy efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid flow batteries, and in particular to a universal electrode frame and a liquid flow battery stack suitable for various liquid flow battery stacks. Background Art

[0002] Liquid flow battery energy storage technology is a new type of power system energy storage technology. It converts electrical energy into chemical energy and stores it in liquid electrolytes, and then converts chemical energy into electrical energy when needed. This technology has the characteristics of intrinsic safety, long-term energy storage capacity, flexible and easy deployment, and is particularly suitable for large-scale energy storage systems, such as new energy grid connection and other application scenarios. The liquid flow battery electrode frame is an important component of the liquid flow battery stack. It not only supports the electrode, but also is responsible for the uniform distribution and flow of the electrolyte to ensure that the electrolyte can flow evenly to the electrode area, reduce concentration polarization, and improve battery performance.

[0003] In the currently known flow battery stacks, the electrode frames and their applications in the stacks are:

[0004] ① The electrode frame does not have multi-level shunt channels or the main channel and shunt channels are not distributed reasonably;

[0005] ② There is no flexible graphite flow channel plate in the reaction zone;

[0006] ③One electrode frame can only be matched with one graphite flow channel plate to form one flow field structure;

[0007] ④One electrode frame can only be used for one flow battery stack.

[0008] The defects or problems of the existing technology mainly include the following aspects:

[0009] 1. The electrode frame has no multi-stage shunt channels or the main channel and shunt channels are not distributed properly, which will cause uneven electrolyte distribution and increase flow resistance, aggravate concentration polarization of the flow battery stack, reduce efficiency and increase pump consumption, and reduce the overall performance of the stack;

[0010] 2. There is no flexible graphite flow channel plate in the reaction zone. The electrolyte will diffuse irregularly and inefficiently in the porous electrode in the form of seepage, making the electrolyte unevenly distributed and even causing dead zones. It also greatly increases the flow resistance, aggravates the concentration polarization, increases pump consumption, reduces the performance of the stack, and affects the service life of the stack.

[0011] 3. One electrode frame can only be matched with one graphite flow channel plate to form a flow field structure for one liquid flow battery stack; this limits the use of the electrode frame and cannot be flexibly adapted to a variety of needs; at the same time, it increases the cost of the battery stack. Summary of the invention

[0012] In order to solve the above technical problems, the present invention provides a universal electrode frame and a liquid flow battery stack suitable for a variety of liquid flow battery stacks. According to different requirements of the battery stack, a universal electrode frame is designed, which can be matched with different flexible graphite plate flow channels and porous electrodes to form different flow field structures, which are suitable for a variety of different liquid flow battery stacks; the electrolyte distribution is more uniform, the flow resistance is smaller, the concentration polarization caused by uneven electrolyte distribution is reduced, the voltage efficiency and energy efficiency are improved, the cost is reduced, and the comprehensive performance of the battery stack is improved.

[0013] The design principle is as follows:

[0014] The flow channel design of the electrode frame includes levels, depth, width, shape, etc., and fully considers factors such as the flow channel width, depth and width of the flow channel ridge of the matching flexible graphite flow channel and the porosity and thickness of the porous electrode. Theoretical design is combined with CFD simulation to optimize and form a variety of flow field structures; the electrolyte enters the flow field structure from the liquid inlet, enters the various levels of liquid inlet branch channels through the liquid inlet main channel, and is redistributed into the flow channel of the graphite flow channel plate located in the reaction zone, and then infiltrates the porous electrode under the flow channel ridge under the action of pressure, and then flows out of the flow field structure through the various levels of liquid outlet branch channels, the liquid outlet main channel, and the liquid outlet of the electrode frame in turn.

[0015] The technical solution is as follows:

[0016] A universal electrode frame suitable for various liquid flow battery stacks, comprising a liquid inlet, a liquid outlet, a liquid inlet main channel, liquid inlet branch channels at various levels, a reaction zone, a liquid outlet main channel, and liquid outlet branch channels at various levels. The reaction zone is used to place reaction electrodes and a flow channel plate. The liquid inlet main channel and the liquid inlet branch channels at various levels connect the liquid inlet and the reaction zone. The liquid outlet main channel and the liquid outlet branch channels at various levels connect the reaction zone and the liquid outlet. The flow channel plates of the liquid inlet branch channels at various levels and the liquid outlet branch channels at various levels are movably connected to the reaction zone. The liquid inlet branch channels at various levels and the liquid outlet branch channels at various levels are formed by combining changes in the shape, position, size and number of support bars.

[0017] Furthermore, the support bar is in the shape of a quadrilateral or a triangle, and a figure formed by changing a straight line into a curve or by chamfering the vertices on this shape.

[0018] Furthermore, the depth of the support strips is accurate to 0.1 mm.

[0019] Furthermore, the number of the liquid inlet multi-stage branch channel and the liquid outlet multi-stage branch channel is 2 to 5, and the width is 1.5 to 5.5 mm.

[0020] Furthermore, the depths of the liquid inlet main channel, the liquid outlet main channel, the liquid inlet multi-stage branch channel, and the liquid outlet multi-stage branch channel are 0.8 mm to 2 mm.

[0021] Furthermore, the flow channel plate and the bipolar plate are integrally formed and embedded in the reaction zone. During assembly, the bipolar plate and the electrode frame are fixed by a positioning device, and the corresponding flow channel plate is fixed.

[0022] Furthermore, the flow channel plate is a parallel flow channel plate or an interdigitated flow channel plate.

[0023] Furthermore, the flow channel of the flow channel plate is 2 to 5 mm wide and 2.5 to 3.9 mm deep;

[0024] Further, the flow channel ridge width of the flow channel plate is 3 to 19 mm;

[0025] A liquid flow battery stack with a universal electrode frame, wherein the electrode frame is in the middle, a reaction electrode and a flow channel plate and a bipolar plate combination structure are respectively located in front of and behind the electrode frame, and the reaction electrode and the flow channel plate are embedded in a reaction area.

[0026] Compared with the prior art, the universal electrode frame and flow battery stack of the present invention have the following advantages:

[0027] ① Through the optimized design of the main channel and multi-stage branch channel in the electrode frame, the uniformity of electrolyte distribution can be effectively improved and the flow resistance can be reduced, thereby reducing the concentration polarization and pump consumption of the battery stack, improving the voltage efficiency and enhancing the performance of the battery stack.

[0028] ② According to different usage requirements, through design simulation, the universal electrode frame can be matched with different flexible graphite flow channel plates and porous electrodes to form an optimized flow field structure, which can further optimize the electrolyte distribution, reduce concentration polarization within a single section and between different numbers of sections, improve voltage efficiency, and improve energy efficiency.

[0029] ③ The electrode frame, especially the mass-produced electrode frame, is mostly made by mold injection molding, which has high R&D and production costs. The present invention provides a universal electrode frame and liquid flow battery stack suitable for a variety of liquid flow battery stacks, which not only changes the limitation of the traditional design that one electrode frame can only be used for one stack, and the electrode frame and stack structure are hard to adjust due to changes in demand, but can be adjusted to match different flow field structures and stacks according to actual needs; and the same cost can be shared among several liquid flow battery stack products, which can effectively reduce costs and improve corporate benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the universal electrode frame of the present invention;

[0031] Figure 2 This is a schematic diagram of the flow field of the first type of flow channel plate type A;

[0032] Figure 3 This is a schematic diagram of the flow field of the second type of flow channel plate type B;

[0033] Figure 4This is a schematic diagram of the C-type flow field of the third type of flow channel plate;

[0034] Figure 5 This is a schematic diagram of the D-type flow field of the fourth type of flow channel plate;

[0035] Figure 6 It is a schematic diagram of the pre-assembled integrated structure of the flow channel plate and the bipolar plate;

[0036] Figure 7 It is a schematic diagram of the assembly of the electrode, flow channel plate and electrode frame.

[0037] Wherein: 1. liquid inlet, 2. liquid inlet main channel, 3. primary liquid inlet branch channel, 4. secondary liquid inlet branch channel, 5. tertiary liquid inlet branch channel, 6. quaternary liquid inlet branch channel, 7. liquid outlet, 8. liquid outlet main channel, 9. primary liquid outlet branch channel, 10. secondary liquid outlet branch channel, 11. tertiary liquid outlet branch channel, 12. quaternary liquid outlet branch channel, 13. reaction zone, 14. support bar, 15. flow channel ridge, 16. flow channel, 17. bipolar plate, 18. flow channel plate, 19. combined structure of flow channel plate and bipolar plate, 20. electrode frame, 21. reaction electrode. DETAILED DESCRIPTION

[0038] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the examples, but the content of the present invention is not limited to the following examples. Unless otherwise specified, the experimental methods used in the present invention are conventional methods, and the experimental equipment, materials, reagents, etc. used can be purchased from chemical companies.

[0039] The main structural difference between the present invention and the prior art lies in that the specific designs of the liquid inlet / outlet flow channels at each level are different, including the spacing between the upper and lower flow channels, the flow channel width, the width of the flow channel support strips, and especially the last level of flow channels to form a variety of different flow fields in conjunction with different flow channel plates in the reaction zone.

[0040] The technical innovations of the present invention mainly include:

[0041] 1. In order to solve the problem of uneven electrolyte distribution and increased flow resistance caused by the electrode frame having no multi-level shunt channels or unreasonable distribution of the main channel and the shunt channels, the electrode frame adopts a design that combines the main channel with the multi-level shunt channels and optimizes the width and depth of the flow channels to improve the uniformity of electrolyte distribution and reduce flow resistance.

[0042] 2. The optimized design of the electrode frame flow channel fully considers the combination of different graphite flow channel plates and various porous electrodes, and forms a variety of flow field structures in the reaction area to meet different needs, further improve the uniformity of electrolyte distribution and reduce flow resistance, thereby improving voltage efficiency and energy efficiency.

[0043] 3. Traditionally, one electrode frame can only be used for one battery stack design. Once the demand changes, it is difficult to adjust the electrode frame and the flow field structure. The universal electrode frame provided by the present invention can be adjusted to match different graphite flow channel plates and a variety of porous electrodes according to actual needs to form different flow field structures and battery stacks.

[0044] Example 1

[0045] The invention provides a universal electrode frame suitable for various liquid flow battery stacks.

[0046] The electrode frame 20 is composed of a liquid inlet 1, a liquid outlet 7, a liquid inlet main channel 2, liquid inlet branch channels at various levels, a reaction zone 13, a liquid outlet main channel 8, and liquid outlet branch channels at various levels. The reaction zone 13 is used to place a reaction electrode 21 and a flow channel plate 18. The liquid inlet main channel 2 and the liquid inlet branch channels at various levels connect the liquid inlet 1 and the reaction zone 13. The liquid outlet main channel 8 and the liquid outlet branch channels at various levels connect the reaction zone 13 and the liquid outlet 7.

[0047] The transition from the liquid inlet main channel 2 and the liquid outlet main channel 8 to the liquid inlet branch channels at various levels and the liquid outlet branch channels at various levels is formed by combining the changes in the shape, position, size and number of the support bars 14; the basic shape of the support bars 14 is a quadrilateral or a triangle, including a rectangle, a square, a trapezoid and an irregular quadrilateral, as well as a figure formed by changing a straight line into a curve or chamfering the vertex on this shape; the position, size and number can be adjusted as needed; in addition to the shape, position, size and number of the branch channels at various levels, which can be flexibly changed by adjusting the support bars 14, the depth can also be adjusted at the level of 0.1 mm as needed; thereby achieving the redistribution of the electrolyte during the flow process.

[0048] In the reaction zone 13, a parallel flow channel plate or an interdigitated flow channel plate made of a flexible graphite plate and a reaction electrode 21 are provided. A plurality of liquid inlet channels and liquid outlet channels are provided on the flow channel plate 18. The liquid inlet channel is connected to the last level of the liquid inlet branch channel of the electrode frame 20, and the liquid outlet channel is connected to the last level of the liquid outlet branch channel of the electrode frame 20. The electrolyte enters the liquid inlet branch channels of each level from the liquid inlet port 1 through the liquid inlet main channel 2 and is redistributed before entering the liquid inlet channel of the flow channel plate 18 located in the reaction zone 13. Then, under the action of pressure, it flows into the reaction electrode 21 through the bottom of the cross-over portion (flow channel ridge 15) of the flow channel plate 18 to complete the redox reaction, and then passes through the liquid outlet channel of the flow channel plate 18, the liquid outlet branch channels of each level of the electrode frame 20, and the liquid outlet main channel 8 in sequence, and flows out from the liquid outlet port 7.

[0049] The reaction electrode 21 has the same size as the reaction area 13 and fills the reaction area 13 .

[0050] The flow channel plate 18 is movably connected to the reaction zone 13. The flow channel plate 18 and the bipolar plate 17 are bonded into a whole in advance using a jig or molded or rolled into one piece, and are just embedded in the reaction zone 13 when used. During assembly, the bipolar plate 17 and the electrode frame 20 are fixed by a positioning device, and the corresponding flow channel plate 18 will not move.

[0051] The assembly and fixing of the flow channel plate 18, the bipolar plate 17 and the reaction electrode 21 are as follows: Figure 6-7 As shown, the electrode frame 20 is in the middle, the reaction electrode 21 and the flow channel plate and bipolar plate combination structure 19 are respectively located in front of and behind the electrode frame 20 , and the reaction electrode 21 and the flow channel plate 18 are embedded in the reaction area 13 .

[0052] like Figure 1 As shown, a universal electrode frame designed according to the requirements and made by machining or injection molding has a thickness of 2.5 mm to 4 mm, the cross-section of the liquid inlet 1 and the liquid outlet 7 is circular, and the diameter is φ8 to φ30 mm; the width of the liquid inlet main channel 2 and the liquid outlet main channel 8 is 5 to 29 mm; the number of the liquid inlet multi-stage branch channel and the liquid outlet multi-stage branch channel is 2 to 5, Figure 1 The situation is described only by assuming that the number of the branch channels is 4. The width is 1.5 to 5.5 mm, and the depths of the liquid inlet main channel 2, the liquid outlet main channel 8, the liquid inlet multi-stage branch channel, and the liquid outlet multi-stage branch channel are 0.8 mm to 2 mm.

[0053] like Figure 2 to Figure 4 As shown, according to different requirements of the battery stack design, the universal electrode frame can be matched with different parallel flexible graphite flow channel plates and reaction electrodes 21 to form different flow field structures, and can be applied to a variety of liquid flow battery stacks: forming a type A flow field with the first type of flow channel plate and porous electrode, forming a type B flow field with the second type of flow channel plate and porous electrode, forming a type C flow field with the third type of flow channel plate and porous electrode, and forming a type D flow field with the fourth type of flow channel plate and porous electrode; wherein the flow channel 16 of the flow channel plate 18 is 2 to 5 mm wide, the flow channel ridge 15 is 3 to 19 mm wide, and the flow channel 16 is 2.5 to 3.9 mm deep; the reaction electrode 21 is 0.4 to 3 mm thick and has a porosity of 0.65 to 0.98; so that the electrolyte has good performance in terms of uniform distribution and pressure loss control.

[0054] Figure 6 This shows that the flow field is parallel. Figures 2 to 5 The assembled flow channel plate 18 and the last-stage flow channel of the electrode frame 20 form an interdigital flow field.

[0055] The electrolyte enters the various levels of liquid inlet branch channels from the liquid inlet 1 through the liquid inlet main channel 2 for redistribution and then enters the flow channel 16 of the flow channel plate 18 located in the reaction area 13, and then infiltrates the reaction electrode 21 under the action of pressure through the bottom of the flow channel ridge 15, and then passes through the various levels of liquid outlet branch channels of the electrode frame 20, the liquid outlet main channel 8, and flows out from the liquid outlet 7; during the charging and discharging process, the universal electrode frame is matched with different flow channel plates 18 and reaction electrodes 21 to form a variety of new flow field structures, so that the electrolyte distribution is more uniform and the flow resistance is smaller; it can effectively reduce concentration polarization, improve voltage efficiency and energy efficiency, and thus improve the performance of the battery stack.

[0056] The application field of the present invention is the liquid flow battery energy storage industry, and the application method is the all-vanadium liquid flow battery stack and system. Potential application methods are various all-vanadium liquid flow battery stacks. The universal electrode frame produced by the present invention has been applied to various stacks and achieved excellent performance, and has been running stably for a long time without obvious attenuation, leakage, etc.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A universal electrode frame suitable for various liquid flow battery stacks, comprising a liquid inlet (1), a liquid outlet (7), a liquid inlet main channel (2), liquid inlet branch channels at various levels, a reaction zone (13), a liquid outlet main channel (8), and liquid outlet branch channels at various levels, wherein the reaction zone (13) is used to place a reaction electrode (21) and a flow channel plate (18), the liquid inlet main channel (2) and the liquid inlet branch channels at various levels connect the liquid inlet (1) and the reaction zone (13), and the liquid outlet main channel (8) and the liquid outlet branch channels at various levels connect the reaction zone (13) and the liquid outlet (7), wherein: The flow channel plates (18) of each level of liquid inlet flow channel and each level of liquid outlet flow channel are movably connected to the reaction zone (13), and each level of liquid inlet flow channel and each level of liquid outlet flow channel are formed by combining the changes in the shape, position, size and number of the support bars (14).

2. The universal electrode frame applicable to various flow battery stacks according to claim 1 is characterized in that: The support bar (14) is in the shape of a quadrilateral or a triangle, and a figure formed by changing a straight line into a curve or by chamfering the vertex on the shape.

3. The universal electrode frame applicable to various flow battery stacks according to claim 1 is characterized in that: The depth of the support strip (14) is accurate to 0.1 mm.

4. The universal electrode frame applicable to various flow battery stacks according to claim 1 is characterized in that: The number of the liquid inlet multi-stage branch channel and the liquid outlet multi-stage branch channel is 2 to 5, and the width is 1.5 to 5.5 mm.

5. The universal electrode frame applicable to various flow battery stacks according to claim 1 is characterized in that: The depths of the liquid inlet main channel (2), the liquid outlet main channel (8), the liquid inlet multi-stage branch channel, and the liquid outlet multi-stage branch channel are 0.8 mm to 2 mm.

6. The universal electrode frame applicable to various flow battery stacks according to claim 1 is characterized in that: The flow channel plate (18) and the bipolar plate (17) are integrally formed and embedded in the reaction zone (13); during assembly, the bipolar plate (17) and the electrode frame (20) are fixed by a positioning device, and the corresponding flow channel plate (18) is fixed.

7. The universal electrode frame applicable to various flow battery stacks according to claim 1 is characterized in that: The flow channel plate (18) is a parallel flow channel plate or an interdigitated flow channel plate.

8. The universal electrode frame applicable to various flow battery stacks according to claim 1 is characterized in that: The flow channel (16) of the flow channel plate (18) has a width of 2 to 5 mm and a depth of 2.5 to 3.9 mm.

9. The universal electrode frame applicable to various flow battery stacks according to claim 1, characterized in that: The flow channel ridge (15) of the flow channel plate (18) has a width of 3 to 19 mm.

10. A liquid flow battery stack with a universal electrode frame, characterized in that: The electrode frame (20) is in the middle, the reaction electrode (21) and the flow channel plate and bipolar plate combination structure (19) are respectively located in front of and behind the electrode frame (20), and the reaction electrode (21) and the flow channel plate (18) are embedded in the reaction area (13).

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