Bipolar plate and flow battery assembled by same

Abstract

The invention belongs to the technical field of batteries, and particularly relates to a bipolar plate and a flow battery assembled by the bipolar plate. By adopting the flow battery bipolar electrode with the flow channel structure under the combined action of the main flow channel and the auxiliary flow channel, the graphite felt can be more quickly and uniformly filled with electrolyte, the aim of uniformly distributing the electrolyte is fulfilled, the pump work loss is effectively reduced, and the performance of the flow battery is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to a bipolar plate and a liquid flow battery assembled thereon. Background Art

[0002] With the continuous progress of the country and society, the demand for energy is also increasing. The combustion of fuels such as coal and oil provides a large amount of energy, but the environmental problems brought about are equally severe. Therefore, the development and utilization of energy is particularly critical. At present, the world is vigorously developing renewable energy, such as wind energy, solar energy and tidal energy. However, due to the mismatch between the amount of electricity generated by renewable energy and the corresponding demand, the two cannot generate stable electricity. Therefore, large-scale energy storage systems can effectively alleviate this limitation, and liquid flow batteries are one of the typical large-scale energy storage systems. Due to the independent regulation of power and capacity, high safety and long life, it is possible, popular all over the world, and successfully commercialized.

[0003] Liquid flow batteries are mainly composed of end plates, bipolar plates, current collectors, graphite felt electrodes, ion conduction membranes and other major components. The electrolytes of the positive and negative electrodes enter the battery device through a peristaltic pump to form a circulation loop. As one of the key components, the bipolar plate is particularly important, and the unique flow channel design is the key to allowing the electrolyte to flow evenly through the electrodes. Therefore, under the condition of the same pump power, the faster and more evenly the electrolyte flows in the porous electrode, the smaller the concentration polarization is, and the higher the battery performance is. Summary of the invention

[0004] The first object of the present invention is to provide a bipolar plate that can allow the electrolyte to fill the graphite felt faster and more evenly, achieve the goal of uniform electrolyte distribution, effectively reduce pump power loss, and provide the performance of a liquid flow battery.

[0005] A bipolar plate, comprising a bipolar plate body, wherein a flow field structure in a rectangular shape is arranged in the center of the bipolar plate body, wherein the flow field structure comprises a main flow channel, an auxiliary flow channel, a liquid inlet and a liquid outlet; two serpentine-shaped auxiliary flow channels are symmetrically arranged in the middle of adjacent main flow channels and are connected through the auxiliary flow channels; The number of the main channels is 2n+1, where n is a natural number greater than or equal to 0; On two adjacent main channels, one main channel is provided with a liquid inlet, and the other main channel is provided with a liquid outlet; that is, the liquid inlet and the liquid outlet are provided adjacent to each other; The width and depth of the main flow channel are much greater than those of the auxiliary flow channel.

[0006] Furthermore, on the back side of the bipolar plate body, O-ring grooves are provided at the positions of the liquid outlet and the liquid inlet, and fluororubber sealing rings are placed in the O-ring grooves. The above arrangement can reduce the risk of electrolyte leakage.

[0007] Further, the number of the main channels is 2n+1, n is a natural number greater than or equal to 1, and they are named as the 1st, 2nd, 3rd ... 2n+1th main channels, n is a natural number greater than or equal to 1; Liquid inlets are respectively provided at both ends of the 2nth main flow channel, where n is a natural number greater than 0; A liquid outlet is provided in the middle of the 2n+1th main flow channel, where n is a natural number greater than or equal to 0; That is, a main channel with two liquid inlets is arranged in the middle of the main channel with the liquid outlet.

[0008] Furthermore, the inlet and outlet have the same aperture size. Keeping the inlet and outlet apertures consistent can ensure the balance of the flow pressure of the electrolyte in the entire system and prevent excessive pressure or low pressure at one end. If the aperture sizes are inconsistent, it may cause uneven flow rate and pressure, thereby affecting the uniform distribution of the electrolyte. The flow of electrolyte in a flow battery is the key to the efficient battery reaction. The same inlet and outlet apertures help the electrolyte to be evenly distributed inside the battery stack, ensuring that all cells of the battery can obtain the same flow and reactants, thereby improving the reaction efficiency and battery life. The same aperture size of the inlet and outlet can keep the flow resistance of the fluid in the bipolar plate consistent. If the inlet and outlet apertures are inconsistent, the smaller aperture will increase the local fluid resistance, resulting in uneven flow and affecting battery performance.

[0009] Furthermore, positioning holes are provided on the bipolar plate body to achieve fixation of the bipolar plate.

[0010] Furthermore, the cross-section of the bipolar plate body is in the shape of a rectangle.

[0011] Furthermore, a convex plate is provided at a corner of the bipolar plate body, and the convex plate and the bipolar plate body are integrally formed.

[0012] The second object of the present invention is to provide a liquid flow battery, which includes two rectangular bipolar plates, two electrode frames are arranged in the middle of the two bipolar plates, a proton exchange membrane is placed between the two electrode frames, current collecting plates are arranged outside the two bipolar plates, insulating plates are arranged outside the current collecting plates, and end plates are arranged outside the insulating plates; the liquid inlets and liquid outlets of the end plates, current collecting plates, insulating plates and bipolar plates are at the same position, the liquid inlets of the end plates, current collecting plates, insulating plates and bipolar plates are connected, and the liquid outlets of the end plates, current collecting plates, insulating plates and bipolar plates are connected.

[0013] Furthermore, the thickness of the fluororubber sealing ring is greater than the sum of the thicknesses of the current collecting plate and the insulating plate, the diameters of the liquid inlet and outlet of the current collecting plate and the insulating plate are greater than the diameter of the fluororubber sealing ring, and the fluororubber sealing ring passes through the liquid inlet and outlet of the current collecting plate and the insulating plate and extends out of the back side of the insulating plate.

[0014] The third object of the present invention is to provide another liquid flow battery, which includes two bipolar plates with convex plates, two electrode frames are arranged in the middle of the two bipolar plates, a proton exchange membrane is placed between the two electrode frames, insulating plates are arranged on the outside of the two bipolar plates, and end plates are arranged on the outside of the insulating plates; current collecting plates are respectively fixed on the convex plates of the two bipolar plates; the liquid inlet and liquid outlet of the end plate, insulating plate and bipolar plate are in the same position, the liquid inlet of the end plate, insulating plate and bipolar plate are connected, and the liquid outlet of the end plate, insulating plate and bipolar plate are connected.

[0015] Furthermore, the thickness of the fluororubber sealing ring is greater than the thickness of the insulating plate, the diameter of the liquid inlet and outlet of the insulating plate is greater than the diameter of the fluororubber sealing ring, and the fluororubber sealing ring passes through the liquid inlet and outlet of the insulating plate and extends out of the back of the insulating plate.

[0016] The functions of each board are as follows: End plates: Located at both ends of the battery stack, they are used to fix and compress the entire battery stack; they are usually made of metal materials and can provide the mechanical strength and stability required for the battery stack. The end plates contain fluid inlets and outlets for the inflow and outflow of electrolyte.

[0017] Insulator plates: Inside the battery stack, they are used to isolate adjacent electrode plates to prevent short circuits; they are usually made of materials with good electrochemical stability and strong insulation properties. Insulator plates help maintain a uniform distribution of the electric field inside the battery stack.

[0018] Current collecting plate: The current collecting plate is attached to both sides of the electrode plate and is used to collect and transmit electrons. It can improve the conduction efficiency of electrons, help reduce the internal resistance of the battery, and improve the overall performance of the battery.

[0019] Bipolar plate: It acts as the anode and cathode of two adjacent single cells at the same time. It mainly plays the role of conducting electricity and isolating the electrolyte. It has fluid channels, and the electrolyte is evenly distributed through the fluid channels to improve battery performance.

[0020] Electrode frame: used to fix and support the electrode plates and keep them in the correct position in the battery stack; the electrode frame helps maintain uniform spacing between the electrode plates and prevent electrolyte leakage or electrode damage due to uneven pressure.

[0021] Furthermore, the thickness of the O-ring groove is greater than the thickness of the insulating plate, the diameters of the liquid inlet and outlet of the insulating plate are greater than the diameter of the O-ring groove, and the fluororubber sealing ring passes through the liquid inlet and outlet of the insulating plate and extends out of the back of the insulating plate.

[0022] Furthermore, the electrode frame is made of a fluororubber pad with a graphite felt electrode in the middle, the end plate is made of an aluminum plate, the bipolar plate is a graphite plate, the current collecting plate is a gold-plated copper plate, and the insulating plate is made of polytetrafluoroethylene.

[0023] Furthermore, the end plate, the current collecting plate and the bipolar plate are fixedly connected by a bolt assembly.

[0024] Beneficial technical effects of the present invention: The present invention adopts a liquid flow battery bipolar plate flow channel with a flow channel structure in which a main flow channel and an auxiliary flow channel work together. The electrolyte enters the bipolar plate flow channel from the middle liquid inlet and first quickly fills the middle main flow channel. The electrolyte will first choose to flow through the graphite felt electrode and then reach the upper main flow channel and the lower main flow channel in turn. Then the electrolyte flows out of the bipolar plate from the liquid outlet, and part of the liquid will flow through the auxiliary flow channel. The auxiliary flow channel can buffer the impact pressure of the electrolyte and help the electrolyte fill the graphite felt electrode faster. Under the condition of the same pump power, the electrolyte flows through the graphite felt electrode more evenly, and the battery performance will be higher. Figure 1 Schematic diagram of the structure of the bipolar plate of Example 1; Figure 2 Schematic diagram of the structure of the bipolar plate of Example 2; Figure 3 Schematic diagram of the back structure of the bipolar plate of Example 1; Figure 4 Schematic diagram of the back structure of the bipolar plate of Example 2; Figure 5 This is a schematic diagram of the structure of the flow battery of Example 3; Figure 6 is a schematic structural diagram of a flow battery according to Example 4; Figure 7 This is a working diagram of the flow battery of Example 4; Figure 8 The Coulomb efficiency comparison between the main and auxiliary flow channels in Example 1 and the existing traditional serpentine flow channel; Fig. 9 The voltage efficiency comparison between the main and auxiliary flow channels in Example 1 and the existing traditional serpentine flow channel; Fig.10 The energy efficiency comparison between the main and auxiliary flow channels in Example 1 and the existing traditional serpentine flow channels is shown in FIG.

[0025] In the figure: 1. Bipolar plate; 11. bipolar plate body, 12. main flow channel, 13. auxiliary flow channel, 14. liquid inlet, 15. liquid outlet, 16. O-ring groove, 17. positioning hole, 18. convex plate; 2. Electrode frame; 3. Proton exchange membrane; 4. Current collecting plate; 5. Insulating plate; 6. End plate; 7. Graphite felt electrode. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] The present invention provides a bipolar plate 1, comprising a bipolar plate body 11, wherein a flow field structure in a rectangular shape is disposed in the center of the bipolar plate body 11, wherein the flow field structure comprises a main flow channel 12, an auxiliary flow channel 13, a liquid inlet 14 and a liquid outlet 15; two serpentine-shaped auxiliary flow channels 13 are symmetrically disposed in the middle of adjacent main flow channels 12, and are connected through the auxiliary flow channels 13; The number of the main channels 12 is 2n+1, where n is a natural number greater than or equal to 0; On two adjacent main channels 12 , one main channel 12 is provided with a liquid inlet 14 , and the other main channel 12 is provided with a liquid outlet 15 ; that is, the liquid inlet 14 and the liquid outlet 15 are provided adjacent to each other; the width and depth of the main channel 12 are much greater than those of the auxiliary channel 13 .

[0029] Furthermore, on the back of the bipolar plate body 11, an O-ring groove 16 is provided at the position of the liquid outlet 15 and the liquid inlet 14, and a fluororubber sealing ring is placed in the O-ring groove 16. The above arrangement can reduce the risk of electrolyte leakage.

[0030] Furthermore, the inlet 14 and the outlet 15 have the same pore size. Keeping the inlet 14 and the outlet 15 consistent in pore size can ensure the balance of flow pressure of the electrolyte in the entire system and prevent excessive pressure or too low pressure at one end. If the pore sizes are inconsistent, it may cause uneven flow rate and pressure, thereby affecting the uniform distribution of the electrolyte. The flow of electrolyte in a flow battery is the key to the efficient battery reaction. The same inlet and outlet pore size helps to evenly distribute the electrolyte inside the battery stack, ensuring that all cells of the battery can obtain the same flow and reactants, thereby improving the reaction efficiency and battery life. The same pore size of the inlet 14 and the outlet 15 can keep the flow resistance of the fluid in the bipolar plate 1 consistent. If the inlet and outlet pore sizes are inconsistent, the smaller pore size will increase the local fluid resistance, resulting in uneven flow and affecting battery performance.

[0031] Furthermore, positioning holes 17 are provided on the bipolar plate body 11 to fix the bipolar plate 1 .

[0032] The present invention is further described in detail below through the accompanying drawings and examples.

[0033] Embodiment 1 A rectangular bipolar plate 1 includes three main channels 12 like Figure 1 , 3 As shown, a bipolar plate 1 includes a rectangular bipolar plate body 11, wherein the bipolar plate body 11 has a thickness of 8 mm, a length of 98.5 mm, and a width of 78.5 mm; the area of ​​the flow field structure in the middle of the bipolar plate body 11 is 24 cm 2 , length 60mm, width 40mm; The flow field structure is provided with a first main flow channel 12, a second main flow channel 12 and a third main flow channel 12 in sequence from top to bottom. The three main flow channels 12 are evenly distributed in the upper, middle and lower parts of the flow field, and have a size of 40 mm in length, 4 mm in width and 1.5 mm in depth. Two liquid inlets 14 are distributed on the left and right sides of the middle of the second main channel 12 in the horizontal direction, and are symmetrically distributed on the left and right sides, and have a diameter of 4 mm; two liquid outlets 15 are respectively arranged in the middle of the first main channel 12 and the third main channel 12, and are symmetrically distributed up and down, and have a diameter of 4 mm; Two serpentine-shaped auxiliary flow channels 13 are arranged between the first main flow channel 12 and the second main flow channel 12, and the auxiliary flow channels 13 are connected; two serpentine-shaped auxiliary flow channels 13 are arranged between the second main flow channel 12 and the third main flow channel 12, and the auxiliary flow channels 13 are connected; that is, the auxiliary flow channels 13 are connected in a serpentine shape from the upper left, upper right, lower left, and lower right directions, respectively, and the length is 19.25mm, the width is 1mm, and the depth is 1mm. On the back of the bipolar plate body 11, an O-ring groove 16 is provided at the position of the liquid outlet 15 and the liquid inlet 14, and a fluororubber sealing ring is placed in the O-ring groove 16. The above arrangement can reduce the risk of electrolyte leakage. In this embodiment, the thickness of the O-ring groove 16 is 5 mm.

[0034] In this embodiment, the four right angles of the bipolar plate 1 are rounded and have a diameter of 10 mm; the positioning holes 17 are distributed at the four end corners of the bipolar plate 1 and have a diameter of 4 mm.

[0035] The working principle of this embodiment: The electrolyte enters from two liquid inlets 14 at the same time, and quickly fills the middle main channel 12. The liquid has two directions. One is to flow through the graphite felt electrode 7 to reach the top and lower main channels 12, and the electrolyte flows out of the bipolar plate 1 from the liquid outlet 15. The second is that the liquid will flow through the auxiliary flow channel 13, and fill the auxiliary flow channel 13 in a serpentine flow from the upper left, upper right, lower left, and lower right directions, so that the three main channels 12 are connected. At the same time, the auxiliary flow channel 13 can reduce the pressure of the electrolyte. The electrolyte can quickly fill the entire flow field and graphite felt to the greatest extent and in the shortest time. Under the same pump power conditions, the electrolyte flows through the graphite felt electrode 7 more evenly, and the battery performance will be higher.

[0036] Example 2 A bipolar plate 1 with a convex plate 18, wherein the bipolar plate 1 comprises three main channels 12 like Figure 2 , 4 As shown, the difference between this embodiment and embodiment 1 is that this embodiment adds a convex plate 18 on the basis of the rectangular bipolar plate body 11. The purpose of adding the convex plate 18 is to facilitate the connection with the positive and negative electrodes. When assembling the liquid flow battery, a gold-plated copper plate is fixed on the convex plate 18.

[0037] Example 3 Liquid flow battery equipped with bipolar plate 1 of Example 1 See also Figure 5 A liquid flow battery comprises two rectangular bipolar plates 1 of embodiment 1, two electrode frames 2 are arranged in the middle of the two bipolar plates 1, current collecting plates 4 are arranged outside the two bipolar plates 1, insulating plates 5 are arranged outside the current collecting plates 4, and end plates 6 are arranged outside the insulating plates 5; the end plates 6, current collecting plates 4, insulating plates 5 and bipolar plates 1 have the same positions of liquid inlet 14 and liquid outlet 15, the end plates 6, current collecting plates 4, insulating plates 5 and bipolar plates 1 are connected to the liquid inlet 14 of the bipolar plates 1, and the end plates 6, current collecting plates 4, insulating plates 5 and bipolar plates 1 are connected to the liquid outlet 15.

[0038] In this embodiment, the thickness of the fluororubber sealing ring on the back of the bipolar plate 1 is greater than the sum of the thicknesses of the current collecting plate 4 and the insulating plate 5, and the diameters of the liquid inlet 14 and the liquid outlet 15 of the current collecting plate 4 and the insulating plate 5 are greater than the diameter of the fluororubber sealing ring. During installation, when the fluororubber sealing ring is placed in the O-ring groove 16, the fluororubber sealing ring passes through the liquid inlet 14 and the liquid outlet 15 of the current collecting plate 4 and the insulating plate 5 and extends out of the back of the insulating plate 5.

[0039] In this embodiment, the electrode frame 2 is made of fluororubber pads, with a graphite felt electrode 7 in the middle, the end plate 6 is made of aluminum plate, the bipolar plate 1 is a graphite plate, the current collector 4 is a gold-plated copper plate, and the insulating plate 5 is a polytetrafluoroethylene plate.

[0040] In this embodiment, the end plate 6 , the current collecting plate 4 , the bipolar plate 1 and the insulating plate 5 are fixedly connected by inserting bolt assemblies into the positioning holes 17 .

[0041] Example 4 Liquid flow battery equipped with bipolar plate 1 of Example 2 See also Figure 6 The difference between this embodiment and embodiment 3 is that the bipolar plate 1 in this embodiment has a convex plate 18, and the current collecting plate 4 is fixed on the convex plate 18. At this time, there is only an insulating plate 5 between the end plate 6 and the bipolar plate 1.

[0042] In this embodiment, the thickness of the fluororubber sealing ring on the back of the bipolar plate 1 is greater than the thickness of the insulating plate 5, the diameters of the liquid inlet 14 and the liquid outlet 15 of the insulating plate 5 are greater than the diameter of the fluororubber sealing ring, and the fluororubber sealing ring passes through the liquid inlet 14 and the liquid outlet 15 of the insulating plate 5 and extends out of the back of the insulating plate 5.

[0043] The workflow of this embodiment is as follows: See also Figure 7 First, the two holes in the horizontal direction of the end plate 6 are the liquid inlet 14, and the two holes in the vertical direction are the liquid outlet 15. A liquid storage tank filled with electrolyte is placed on each side of the liquid flow electromagnetic. Taking the positive electrode as an example, under the action of the pump, the electrolyte is sucked out of the liquid storage tank and enters the pump. After coming out of the pump, it enters the liquid inlet 14 of the end plate 6. The electrolyte passes through the insulating plate 5 and reaches the liquid inlet 14 of the bipolar plate 1. It flows through the flow channel of the bipolar plate 1 and fills the graphite felt electrode 7. There is a proton exchange membrane 3 between the two electrode frames 2. After the electrolyte fills the electrode, it flows out of the bipolar plate 1 through the liquid outlet 15 in the vertical direction of the bipolar plate 1, passes through the current collecting plate 4, reaches the liquid outlet 15 in the vertical direction of the end plate 6, and then returns to the liquid storage tank. The negative electrode is the same as the positive electrode. Connect the power supply to the upper end of the bipolar plate 1, and perform the charge and discharge cycle test through the tester.

[0044] The performance of the flow battery in Example 4 was tested, including the coulombic efficiency, voltage efficiency, and energy efficiency of the battery. The results are as follows: like Figure 8 It can be seen that at 100mA cm -2 At the current density, the pump flow rate is 10mlmin -1 When the coulombic efficiency of the battery in Example 4 is 98.6%, it is 0.1% higher than that of the traditional serpentine flow channel.

[0045] like Fig. 9 It can be seen that at 100mA cm -2 At the current density, the pump flow rate is 10mlmin -1 When the voltage efficiency of the battery composed of the main and auxiliary flow channels 13 is 84.4%, it is 0.6% higher than that of the traditional serpentine flow channel.

[0046] like Fig.10 It can be seen that at 100mA cm -2 At the current density, the pump flow rate is 10mlmin -1 When the main and auxiliary flow channels 13 are connected, the energy efficiency of the battery is 83.2%, which is 0.7% higher than that of the traditional serpentine flow channel.

[0047] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A bipolar plate, characterized in that: It comprises a bipolar plate body (11), wherein a flow field structure in the shape of a "rectangle" as a whole is arranged in the center of the bipolar plate body (11), wherein the flow field structure comprises a main flow channel (12), an auxiliary flow channel (13), a liquid inlet (14) and a liquid outlet (15); two serpentine-shaped auxiliary flow channels (13) are symmetrically arranged in the middle of adjacent main flow channels (12), and are connected via the auxiliary flow channels (13); The number of the main channels (12) is 2n+1, where n is a natural number greater than or equal to 0; On two adjacent main channels (12), one main channel (12) is provided with a liquid inlet (14), and the other main channel (12) is provided with a liquid outlet (15); that is, the liquid inlet (14) and the liquid outlet (15) are arranged adjacent to each other; The width and depth of the main flow channel (12) are much greater than those of the auxiliary flow channel (13).

2. The bipolar plate according to claim 1, characterized in that: On the back side of the bipolar plate body (11), O-ring grooves (16) are respectively provided at the positions of the liquid outlet (15) and the liquid inlet (14), and fluororubber sealing rings are placed in the O-ring grooves (16).

3. The bipolar plate according to claim 1, characterized in that: The number of the main channels is 2n+1, where n is a natural number greater than or equal to 1, and they are named as the 1st, 2nd, 3rd ... 2n+1th main channels, where n is a natural number greater than or equal to 1; Liquid inlets are respectively provided at both ends of the 2nth main flow channel, where n is a natural number greater than 0; A liquid outlet is provided in the middle of the 2n+1th main flow channel, where n is a natural number greater than or equal to 0; That is, a main channel with two liquid inlets is arranged in the middle of the main channel with the liquid outlet.

4. The bipolar plate according to claim 1, characterized in that: A positioning hole (17) is provided on the bipolar plate body (11).

5. The bipolar plate according to claim 2, characterized in that: The cross-section of the bipolar plate body (11) is in the shape of a rectangle.

6. The bipolar plate according to claim 2, characterized in that: A convex plate (18) is provided at a corner of the bipolar plate body (11), and the convex plate (18) and the bipolar plate body (11) are integrally formed.

7. A liquid flow battery equipped with the bipolar plate according to claim 5, characterized in that: The liquid flow battery comprises two rectangular bipolar plates (1), two electrode frames (2) are arranged in the middle of the two bipolar plates (1), a graphite felt electrode (7) is arranged in the middle of the electrode frames (2), a proton exchange membrane (3) is placed between the two electrode frames (2), current collecting plates (4) are arranged on the outside of the two bipolar plates (1), an insulating plate (5) is arranged on the outside of the current collecting plates (4), and an end plate (6) is arranged on the outside of the insulating plate (5); the liquid inlet (14) and liquid outlet (15) of the end plate (6), the insulating plate (5), the current collecting plate (4) and the bipolar plate (1) are at the same position, the end plate (6), the insulating plate (5) and the liquid inlet (14) of the bipolar plate (1) are connected, and the end plate (6), the insulating plate (5), the current collecting plate (4) and the liquid outlet (15) of the bipolar plate (1) are connected.

8. The liquid flow battery equipped with bipolar plates according to claim 7, characterized in that: The thickness of the fluororubber sealing ring is greater than the sum of the thicknesses of the current collecting plate (4) and the insulating plate (5); the diameters of the liquid inlet (14) and the liquid outlet (15) of the current collecting plate (4) and the insulating plate (5) are greater than the diameter of the fluororubber sealing ring; the fluororubber sealing ring passes through the liquid inlet (14) and the liquid outlet (15) of the current collecting plate (4) and the insulating plate (5) and extends out of the back side of the insulating plate (5).

9. A liquid flow battery equipped with the bipolar plate according to claim 6, characterized in that: The liquid flow battery comprises two bipolar plates (1) with convex plates (18), two electrode frames (2) are arranged in the middle of the two bipolar plates (1), a graphite felt electrode (7) is arranged in the middle of the electrode frames (2), a proton exchange membrane (3) is placed between the two electrode frames (2), insulating plates (5) are arranged on the outside of the two bipolar plates (1), and end plates (6) are arranged on the outside of the insulating plates (5); current collecting plates (4) are respectively fixed on the convex plates (18) of the two bipolar plates (1); the liquid inlet (14) and the liquid outlet (15) of the end plate (6), the insulating plate (5) and the bipolar plate (1) are at the same position, the end plate (6), the insulating plate (5) and the liquid inlet (14) of the bipolar plate (1) are connected, and the end plate (6), the insulating plate (5) and the liquid outlet (15) of the bipolar plate (1) are connected.

10. The liquid flow battery equipped with bipolar plates according to claim 9, characterized in that: The thickness of the fluororubber sealing ring on the back of the bipolar plate (1) is greater than the thickness of the insulating plate (5); the diameters of the liquid inlet (14) and the liquid outlet (15) of the insulating plate (5) are greater than the diameter of the fluororubber sealing ring; the fluororubber sealing ring passes through the liquid inlet (14) and the liquid outlet (15) of the insulating plate (5) and extends out of the back of the insulating plate (5).

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