All-vanadium redox flow battery electrode frame and all-vanadium redox flow battery

Abstract

The invention relates to the technical field of redox flow battery energy storage, and discloses an all-vanadium redox flow battery electrode frame and an all-vanadium redox flow battery, the all-vanadium redox flow battery electrode frame comprises a liquid inlet side, a liquid outlet side and an electrode cavity located between the liquid inlet side and the liquid outlet side, the liquid inlet side is provided with a liquid inlet, a liquid inlet flow channel and a liquid inlet buffer tank which are communicated in sequence, and the liquid outlet side is provided with a liquid outlet flow channel; the liquid inlet buffer tank is provided with a plurality of liquid inlet flow guide bodies which are arranged at intervals in the X direction, a gap between every two adjacent liquid inlet flow guide bodies forms a liquid inlet channel, the liquid inlet buffer tank is communicated with the electrode cavity through the liquid inlet channels, and the sizes of every two adjacent liquid inlet flow guide bodies in the X direction are not equal. According to the invention, the distribution uniformity of the electrolyte entering the electrode cavity can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of liquid flow battery energy storage, and in particular to an all-vanadium liquid flow battery electrode frame and an all-vanadium liquid flow battery. Background Art

[0002] The realization of sustainable development of energy and environment is accompanied by the emergence of renewable energy. Renewable energy represented by solar energy and wind energy has been highly valued by countries around the world. In solving the problem of unstable power generation and large-scale energy storage of renewable energy, flow batteries have attracted widespread attention due to their independent output power and capacity, long service life, deep discharge depth, high energy efficiency, no pollution, simple maintenance, low cost, safety and environmental protection. All-vanadium flow batteries have the advantages of high safety, long cycle life, independent design of power and capacity, high efficiency, environmental friendliness, wide temperature operating range, good partial charge performance and diversified application scenarios. It is an advanced technology suitable for large-scale energy storage. To achieve the safe operation and management of large-scale energy storage systems, it is necessary to master the performance characteristics of the core component of flow batteries. The structure of an all-vanadium flow battery stack mainly includes end plates, current collectors, bipolar plates, sealing gaskets, electrodes, electrode frames and other components. Among them, the electrode frame has the important functions of supporting electrodes, receiving conductive bipolar plates, controlling the flow direction of electrolytes, and evenly distributing electrolytes. The existing liquid flow battery electrode frame has the following disadvantages: 1. The flow rate of electrolyte entering the battery stack is reduced, thereby reducing the electrolyte renewal rate; 2. Dead corners for electrolyte flow are easily formed in the electrode area, resulting in uneven distribution of electrolyte in the electrode area, which in turn affects the electrode reaction; 3. The flow of electrolyte on the electrode frame has a large flow resistance, resulting in a too slow electrolyte flow rate. Summary of the invention

[0003] The purpose of the present invention is to overcome the problem of uneven distribution of electrolyte in the electrode area in the prior art, which in turn affects the electrode reaction, and to provide an all-vanadium liquid flow battery electrode frame and an all-vanadium liquid flow battery, which have the advantages of improving the uniformity of electrolyte distribution and improving the coulomb efficiency, voltage efficiency and energy efficiency of the battery.

[0004] In order to achieve the above-mentioned purpose, the present invention provides an electrode frame of an all-vanadium liquid flow battery on one hand, wherein the electrode frame of the all-vanadium liquid flow battery comprises a liquid inlet side, a liquid outlet side and an electrode cavity located between the liquid inlet side and the liquid outlet side, wherein the liquid inlet side is provided with a liquid inlet, a liquid inlet flow channel and a liquid inlet buffer groove, wherein the liquid inlet is communicated with the liquid inlet buffer groove through the liquid inlet flow channel, wherein a liquid inlet guide body arranged at intervals along the X direction is provided between the liquid inlet buffer groove and the electrode cavity, wherein a gap between two adjacent liquid inlet guide bodies forms a liquid inlet channel, wherein the liquid inlet buffer groove is communicated with the electrode cavity through the liquid inlet channel, wherein the sizes of two adjacent liquid inlet guide bodies in the X direction are unequal.

[0005] In a second aspect of the present invention, a flow battery is provided, and the flow battery employs the all-vanadium flow battery electrode frame of the present invention.

[0006] Through the above technical solution, by arranging a plurality of liquid inlet guiding bodies at intervals in the X direction on the liquid inlet side and the sizes of adjacent two liquid inlet guiding bodies in the X direction being unequal, such that the distances between the liquid inlet channels are unequal, the uniformity of the electrolyte distribution entering the electrode chamber can be improved, thereby improving the energy efficiency of the battery and prolonging the service life of the all-vanadium flow battery stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic structural view of the all-vanadium flow battery electrode frame according to an embodiment of the present invention;

[0008] Figure 2 is a schematic structural view of a single cell of the all-vanadium flow battery according to an embodiment of the present invention;

[0009] Figure 3 is a schematic connection view of the all-vanadium flow battery according to an embodiment of the present invention;

[0010] Figure 4 is a schematic structural view of the electrode frame in Comparative Example 1.

[0011] DESCRIPTION OF THE REFERENCE NUMERALS

[0012] 1 Liquid inlet side; 2 Liquid outlet side; 3 Electrode chamber; 11 Liquid inlet; 12 Liquid inlet flow channel; 13 Liquid inlet buffer tank; 14 Liquid inlet guiding body; 21 Liquid outlet; 22 Liquid outlet flow channel; 23 Liquid outlet buffer tank; 24 Liquid outlet guiding body; 121 Main flow channel; 231 Tapered outlet. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0014] In the present invention, unless otherwise specified, the orientation terms such as "upper, lower, left, right" generally refer to the upper, lower, left, and right as shown in the reference drawings; "inner, outer" refer to the inner and outer relative to the contour of each component itself.

[0015] The present invention discloses an all-vanadium flow battery electrode frame, as Figure 1As shown, the all-vanadium redox flow battery electrode frame includes a substrate and a groove formed in the middle of the substrate. A through hole is dug in the middle of the bottom surface of the groove. The inner wall surface of the through hole is welded to a conductive plastic to form an electrode cavity 3 for installing a porous electrode. The remaining two sides opposite to each other in the Y direction of the electrode cavity 3 are respectively formed into a liquid inlet side 1 and a liquid outlet side 2. Among them, a plurality of liquid inlet guiding bodies 14 arranged at intervals in the X direction are provided on the bottom surface of the groove located on the liquid inlet side 1. The area between the plurality of liquid inlet guiding bodies 14 and the groove wall of the groove located on the liquid inlet side 1 is formed into a liquid inlet buffer groove 13. A liquid inlet 11 and a liquid inlet flow channel 12 are further provided on the substrate. The liquid inlet 1 is communicated with the liquid inlet buffer groove 13 through the liquid inlet flow channel 12. The gap between two adjacent liquid inlet guiding bodies 14 is formed into a liquid inlet channel. The liquid inlet buffer groove 13 is communicated with the electrode cavity 3 through the liquid inlet channel. Among them, the sizes of two adjacent liquid inlet guiding bodies 14 in the X direction are not equal, so that the spacing between the liquid inlet channels is not equal.

[0016] It should be noted that in the case of no liquid inlet guiding body 14, the electrolyte cannot flow evenly through the electrode surface. The concentration of the active substance in some areas of the electrode cavity 3 may be too high or too low, resulting in poor transfer of the active substance in the electrolyte, and thus affecting the performance of the all-vanadium redox flow battery. The electrolyte entering from the liquid inlet 11 enters the liquid inlet buffer groove 13 through the liquid inlet flow channel 12, flows freely therein, and enters the electrode cavity 3 through a plurality of liquid inlet channels formed by a plurality of liquid inlet guiding bodies 14 arranged at intervals in the X direction, which can guide the flow of the electrolyte, ensure that the electrolyte flows evenly through the electrode surface, reduce concentration polarization, and improve the charge-discharge efficiency and stability of the battery; compared with the equally spaced liquid inlet channels in the prior art, the non-equidistant liquid inlet channels of the present invention can optimize the fluid flow process and improve the velocity uniformity in the electrode.

[0017] The liquid inlet flow channel 12 is provided with N (N≥1) liquid inlet flow channel outlets communicating with the liquid inlet buffer tank 13. A plurality of liquid inlet guiding bodies 14 are divided into N groups, and each liquid inlet flow channel outlet is correspondingly provided with a group of liquid inlet guiding bodies 14. Since the flow velocity at the position of the liquid inlet flow channel outlet is relatively large after the electrolyte flows out of the liquid inlet flow channel outlet, while the flow velocity at the position far from the liquid inlet flow channel outlet in the liquid inlet buffer tank 13 is relatively small, in order to reduce the velocity gradient in the liquid inlet buffer tank 13 and ensure that the electrode regions far from the liquid inlet flow channel outlet can all obtain sufficient electrolyte supply, in each group of liquid inlet guiding bodies 14 in the present invention, the dimension of the liquid inlet guiding body 14 in the X direction decreases as the distance from the liquid inlet flow channel outlet increases, that is, the distance between the liquid inlet channels decreases as the distance from the liquid inlet flow channel outlet increases. The liquid flow channel outlet is correspondingly provided with the liquid inlet guiding body 14 having the largest dimension in the X direction, guiding the electrolyte at the liquid inlet flow channel outlet to flow in the X direction so as to be distributed as evenly as possible in the electrode cavity 3, ensuring the uniformity of the supply of the active material, further reducing the mass transfer loss, and improving the battery voltage efficiency and the system efficiency. It should be noted that the present invention has no special requirements for the gradient of the dimension of the liquid inlet guiding body 14 in the X direction decreasing as the distance from the liquid inlet flow channel outlet increases. For example, in the direction of increasing distance from the liquid inlet flow channel outlet, the next liquid inlet guiding body 14 can be reduced by 1%-50% compared with the previous one.

[0018] In the present invention, the dimension of the liquid inlet channels in each group of liquid inlet guiding bodies 14 in the X direction increases as the distance from the liquid inlet flow channel outlet increases. The dimension of the liquid inlet channels between the liquid inlet guiding body 14 farthest from the liquid inlet flow channel outlet and the liquid inlet guiding body 14 in the X direction is the largest. By adjusting the dimension and the distance between the liquid inlet guiding bodies 14 according to the distance from the liquid inlet flow channel outlet, the dimension of the liquid inlet guiding body 14 at the position far from the liquid inlet flow channel outlet is smaller and the distance is larger, providing more flow channel space for the electrode region far from the liquid inlet flow channel outlet, reducing the flow resistance, which helps to ensure that the electrode regions far from the liquid inlet flow channel outlet can all obtain sufficient electrolyte supply, promoting the exchange between the active material and the electrolyte, ensuring the uniformity of the supply of the active material, further reducing the mass transfer loss, and improving the battery voltage efficiency. It should be noted that the present invention has no special requirements for the gradient of the dimension of the liquid inlet channels in the X direction increasing as the distance from the liquid inlet flow channel outlet increases. For example, in the direction of increasing distance from the liquid inlet flow channel outlet, the next liquid inlet channel can be increased by 1%-50% compared with the previous one.

[0019] The liquid inlet guiding body 14 is arranged as a cuboid extending in the Y direction, which can effectively reduce the processing difficulty, save the processing cost and can play a role in positioning the electrode.

[0020] Refer to Figure 1As shown in the figure, in the present invention, the liquid inlet flow channel 12 is set as a multi-stage distribution flow channel. Along the material flow direction, the outlet of the last-stage distribution flow channel is formed as a liquid inlet flow channel outlet communicating with the liquid inlet buffer tank 13, and these liquid inlet flow channel outlets are evenly distributed along the X direction. The liquid inlet 11 is arranged in the middle of the main flow channel 121 of the multi-stage distribution flow channel, and the width of the main flow channel 121 is the same as the diameter of the liquid inlet 11. It should be noted that when the width of the main flow channel 121 is smaller than the diameter of the liquid inlet 11, the fluid flow resistance will increase. By adopting the foregoing setting, the electrolyte circulation area can be increased and the pump consumption can be reduced.

[0021] The multi-stage distribution flow channel in the present invention is as Figure 1 shown, and includes a main flow channel 121 extending along the X direction and at least two baffle channels extending along the Y direction. The main flow channel is communicated with the liquid inlet buffer tank 13 through the baffle channels. Among them, a fluid distributor is arranged in each baffle channel; in this way, the electrolyte is divided into two left and right streams through the liquid inlet 11 arranged in the middle of the main flow channel 121 and enters the baffle channels respectively, and is divided into multiple streams through the fluid distributor and enters the liquid inlet buffer tank. The fluid distributor structure for dividing the liquid in the baffle channel into at least two streams is well-known to those skilled in the art and does not belong to the core improvement part of this application, so it will not be elaborated here.

[0022] To reduce the fluid pressure drop and relieve the energy loss of fluid flow, the channels for circulating the electrolyte on the liquid inlet side 1 and the channels for circulating the electrolyte on the liquid outlet side 2 are arranged asymmetrically.

[0023] Specifically, a plurality of liquid outlet guiding fluids 24 arranged at equal intervals along the X direction are provided on the bottom surface of the groove located on the liquid outlet side 2. The area between the plurality of liquid outlet guiding fluids 24 and the groove wall of the groove located on the liquid outlet side 2 is formed as a liquid outlet buffer tank 23. A liquid outlet 21 and a liquid outlet flow channel 22 are provided on the substrate. The liquid outlet 21 is communicated with the liquid outlet buffer tank 23 through the liquid outlet flow channel 22. The gap between two adjacent liquid outlet guiding fluids 24 is formed as a liquid outlet channel, and the liquid outlet buffer tank 23 is communicated with the electrode cavity 3 through the liquid outlet channel.

[0024] The liquid outlet buffer tank 23 is provided with a tapered outlet 231 communicated with the liquid outlet flow channel 22. By means of the tapered structure, the flow rate of the electrolyte is accelerated and the battery polarization is reduced.

[0025] The liquid outlet 21 is arranged in the middle of the liquid outlet flow channel 22 and on the central axis of the substrate in the Y direction. The liquid outlet buffer tank 23 is provided with two tapered outlets 231 symmetrical about the central axis of the substrate in the Y direction. The two ends of the liquid outlet flow channel 22 are respectively communicated with one tapered outlet 231. In this way, the uniform distribution of the fluid flow rate on the liquid outlet side can be ensured.

[0026] The ratio of the width of the liquid outlet flow channel 22 to the diameter of the liquid outlet 21 is 0.22 to 0.28.

[0027] The liquid outlet guiding body 24 is arranged as a long strip extending along the Y direction. One end of the liquid outlet guiding body 24 close to the liquid outlet buffer tank 23 is arranged as a semi-cylindrical body, and the end face of the end close to the electrode is arranged as a rectangle, which is convenient for positioning the electrode.

[0028] The material of the substrate can be polypropylene or polyethylene material, which is corrosion-resistant and easy to process.

[0029] The substrate is arranged as a rectangular plate, and is provided with a sealing groove and positioning holes for positioning and assembling the electrode frame.

[0030] On the basis of the foregoing disclosure, the present invention discloses a vanadium redox flow battery, which includes at least one vanadium redox flow single cell. Each vanadium redox flow single cell includes a diaphragm and the vanadium redox flow battery electrode frame of the present invention for installing electrodes on both sides of the diaphragm. A fluororubber material in the prior art is embedded in the sealing groove opened on the substrate to realize the sealing of the battery. The liquid inlet 11 and the liquid outlet 21 are respectively connected to the electrolyte storage tank through pipes installed with circulation pumps.

[0031] The structural design of the electrode frame of the vanadium redox flow battery stack is a key link to improve the battery performance. It can ensure the uniform distribution of the electrolyte in the stack, reduce the dead zone and short-circuit flow path, enhance the mass transfer efficiency of vanadium ions, and reduce the concentration polarization. At the same time, a reasonable electrode frame structural design can effectively reduce the fluid resistance, reduce the energy consumption of the circulation pump, improve the uniformity of the current distribution, improve the battery stability and cycle life, meet the requirements under different power levels and complex working conditions, and thus support the large-scale application and performance improvement of the vanadium redox flow battery.

[0032] The advantages of the present invention will be illustrated by the following examples, but the present invention is not limited thereto.

[0033] Test method:

[0034] After the single cell is assembled, it is connected to a Blue Electric battery test system with the model CT2001B-5V10A. After turning on the circulation pump to circulate the electrolyte, let it stand for half an hour. The brass sheet lugs in the positive and negative electrode plates are connected to the positive and negative electrode lines of the test system, and a constant current charge and discharge cycle test is carried out with a current density of 100 mA / cm 2 The cut-off voltage during the charging process is 1.7V, and the cut-off voltage during the discharging process is 0.7V.

[0035] Calculation method:

[0036] (1) Coulomb efficiency CE: It is the ratio of the energy storage capacity to the charging capacity.

[0037]

[0038] In the formula, Q dis is the energy storage capacity, A·h; Qch is the charge capacity, A·h; I dis is the discharge current density, mA / cm 2 ; I ch is the charge current density, mA / cm 2 ; t is the charge and discharge time, s.

[0039] (2) Voltage efficiency VE: The voltage efficiency is the ratio of the average discharge voltage to the average charge voltage.

[0040]

[0041] In the formula, is the average discharge voltage, V; is the average charge voltage, V; V dis is the discharge voltage at any time, V; V ch is the charge voltage at any time, V; t dis is the discharge time, s; t ch is the charge time, s.

[0042] (3) Energy efficiency EE: The ratio of the discharge energy to the charge energy.

[0043]

[0044] In the formula, W dis is the discharge energy, W·h; W ch is the charge energy, W·h.

[0045] Example 1

[0046] Taking the all-vanadium redox flow battery single cell assembled with the all-vanadium redox flow battery electrode frame (hereinafter referred to as the electrode frame) provided by the present invention Figure 1 shown as an example. It is assembled by an electrode frame with a positive carbon felt installed and an electrode frame with a negative carbon felt installed. A conductive plastic bipolar plate (the resistivity of the conductive plastic is 120 mΩ·cm) is welded on each electrode frame. The conductive plastic bipolar plate is in contact with the h62 brass sheet current collector, and the current collector is connected to the external circuit. The electrolyte inlet and outlet pipes connected to the electrolyte storage bottle are respectively connected to the inlet and outlet ports of the positive and negative electrode frames. The electrolyte enters from the bottom and exits from the top, passes through the multi-stage distribution channels of the electrode frame, enters the liquid inlet buffer tank 13, and is distributed into the electrode material through multiple liquid inlet channels, and finally returns to the electrolyte storage bottle from the liquid outlet side. The electrode area is 108 cm Figure 2 shown). The positive and negative electrodes use a perfluorosulfonic acid ion exchange membrane. The negative electrolyte of the battery is 500 mL of 1.5 M V 2 , the negative electrolyte of the battery is 500 mL of 1.5 M V 3+ / V 2+ + 3.0 M H2SO4, and the positive electrolyte is 500 mL of 1.5 M VO2+ / VO 2+ +3.0M H2SO4, the electrolyte flow rate is 400 mL / min, and the volume of the electrolyte storage bottle is 1000 mL. The charge-discharge current density is 100 mA / cm 2 , the discharge cut-off voltage is 0.7V, and the charge cut-off voltage is 1.7V.

[0047] The active area ratio of this all-vanadium redox flow battery is 39.7%. When the single cell operates for 1000 cycles, the Coulombic efficiency is 97.70%, the voltage efficiency is 82.15%, and the energy efficiency is 80.26%.

[0048] Example 2

[0049] Different from Example 1, the dimensions of each liquid inlet channel in the X direction are equal.

[0050] Result: The active area ratio of this all-vanadium redox flow battery is 39.7%. When the single cell operates for 1000 cycles, the Coulombic efficiency is 96.84%, the voltage efficiency is 78.09%, and the energy efficiency is 75.62%.

[0051] Comparative Example 1

[0052] Different from Example 1, the Figure 4 shown electrode frame is used, and the liquid inlet current collector and the liquid outlet current collector are not provided, and a single cell of an all-vanadium redox flow battery with the same materials and the same structure as in Example 1 is assembled.

[0053] The active area ratio of this all-vanadium redox flow battery is 37.2%. When the single cell operates for 1000 cycles, the Coulombic efficiency is 95.86%, the voltage efficiency is 71.05%, and the energy efficiency is 68.11%.

[0054] Comparative Example 2

[0055] Different from Example 1, the dimensions of two adjacent liquid inlet current collectors 14 in the X direction are equal.

[0056] Result: The active area ratio of this all-vanadium redox flow battery is 39.7%. When the single cell operates for 1000 cycles, the Coulombic efficiency is 95.96%, the voltage efficiency is 73.24%, and the energy efficiency is 70.28%.

[0057] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. 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 suitable combination of each specific technical feature. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods. But these simple modifications and combinations should also be regarded as the content disclosed by the present invention and all fall within the protection scope of the present invention.

Claims

1. An electrode frame for an all-vanadium liquid flow battery, characterized in that: The all-vanadium liquid flow battery electrode frame comprises a liquid inlet side (1), a liquid outlet side (2) and an electrode cavity (3) located between the liquid inlet side (1) and the liquid outlet side (2); the liquid inlet side (1) is provided with a liquid inlet port (11), a liquid inlet channel (12) and a liquid inlet buffer groove (13) which are connected in sequence; the liquid inlet buffer groove (13) is provided with a plurality of liquid inlet guide bodies (14) arranged at intervals along the X direction; a gap between two adjacent liquid inlet guide bodies (14) forms a liquid inlet channel; the liquid inlet buffer groove (13) is connected to the electrode cavity (3) through the liquid inlet channel; and the sizes of the two adjacent liquid inlet guide bodies (14) in the X direction are unequal.

2. The all-vanadium redox flow battery electrode frame according to claim 1, characterized in that: The plurality of liquid inlet guide bodies (14) are arranged into at least one group, and the liquid inlet flow channel (12) is provided with at least one liquid inlet flow channel outlet connected to the liquid inlet buffer tank (13).

3. The all-vanadium redox flow battery electrode frame according to claim 2, characterized in that: Each of the liquid inlet flow channel outlets is provided with a group of liquid inlet guide bodies (14) correspondingly, wherein: In each group of liquid inlet guide bodies (14), the size of the liquid inlet guide bodies (14) in the X direction decreases as the distance from the outlet of the liquid inlet flow channel increases.

4. The all-vanadium redox flow battery electrode frame according to claim 2 or 3, characterized in that: A group of liquid inlet guide bodies (14) is correspondingly arranged at each of the liquid inlet flow channel outlets, wherein in each group of the liquid inlet guide bodies (14), the size of the liquid inlet channel in the X direction increases as the distance from the liquid inlet flow channel (12) outlet increases.

5. The all-vanadium redox flow battery electrode frame according to any one of claims 1 to 3, characterized in that: The liquid inlet guide body (14) is configured as a rectangular parallelepiped.

6. The all-vanadium redox flow battery electrode frame according to claim 1, characterized in that: The liquid inlet channel (12) is arranged as a multi-stage distribution channel, wherein the liquid inlet (11) is arranged in the middle of a main channel (121) of the multi-stage distribution channel, and the width of the main channel (121) is the same as the diameter of the liquid inlet (11).

7. The all-vanadium redox flow battery electrode frame according to claim 1, characterized in that: The liquid inlet side (1) and the liquid outlet side (2) are arranged asymmetrically; and / or The liquid outlet side (2) is provided with a liquid outlet (21), a liquid outlet flow channel (22) and a liquid outlet buffer groove (23), wherein the liquid outlet (21) is connected to the liquid outlet buffer groove (23) through the liquid outlet flow channel (22), and liquid outlet guide bodies (24) are arranged at equal intervals along the X direction between the liquid outlet buffer groove (23) and the electrode cavity (3), and the gap between two adjacent liquid outlet guide bodies (24) forms a liquid outlet channel, and the liquid outlet buffer groove (23) is connected to the electrode cavity (3) through the liquid outlet channel.

8. The all-vanadium redox flow battery electrode frame according to claim 7, characterized in that: The liquid outlet buffer tank (23) is provided with a tapered outlet (231), and the tapered outlet (231) is communicated with the liquid outlet flow channel; Preferably, the liquid outlet (21) is arranged in the middle of the liquid outlet channel (22), the liquid outlet buffer tank (23) is provided with two symmetrical tapered outlets (231), and both ends of the liquid outlet channel (22) are respectively connected to one of the tapered outlets (231); More preferably, the ratio of the width of the liquid outlet channel (22) to the diameter of the liquid outlet (21) is 0.22 to 0.

28.

9. The all-vanadium redox flow battery electrode frame according to claim 7 or 8, characterized in that: The liquid outlet guiding body (24) is arranged in a long strip shape, and the end surface of the liquid outlet guiding body (24) at one end close to the electrode is arranged in a rectangular shape.

10. An all-vanadium liquid flow battery, characterized in that: The all-vanadium liquid flow battery adopts the all-vanadium liquid flow battery electrode frame described in any one of claims 1-9.

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