Vanadium liquid battery, battery stack and manufacturing method of vanadium liquid battery

Abstract

The invention discloses a manufacturing method of a vanadium redox battery in the technical field of vanadium redox batteries, which comprises the following steps: S1, adding phosphoric acid (H3PO4) and citric acid (molar ratio of 1: (2-4)) into a positive electrolyte, and irradiating the negative electrolyte for 60-80 minutes by adopting ultraviolet light (intensity of 50-60 mW / cm < 2 >); s2, the electrode is a gradient electrode, the surface layer is a Bi (at) MnO2 heterojunction catalyst layer, and the thickness is 50 + / -5 nm; the middle layer is a vertically arranged graphene array, and the interlayer spacing is 2-5nm; the bottom layer is a graphene aerogel diversion layer, the porosity is 90%, and the aperture is 10-50 microns; the electrode is subjected to argon plasma treatment for 10-20 minutes, and pulse electrochemical oxidation is synchronously applied; s3, a flow channel of the bipolar plate is of a three-stage fractal tree-shaped structure, the width of a main channel is 2-3 mm, the branch proportionality coefficient is 0.7-0.8, the branch angle is 45-50 degrees, and the surface of the flow channel is coated with a SiO2 / PTFE super-hydrophobic coating. And long-acting stability and high-purity regulation and control of the electrolyte are realized through phosphoric acid-citric acid synergistic complexing and photochemical reduction coupling.

Description

Technical Field

[0001] The present invention relates to the technical field of vanadium liquid batteries, and specifically relates to a vanadium liquid battery, a battery stack and a manufacturing method thereof. Background Art

[0002] The vanadium liquid battery stack, that is, the stack of all-vanadium redox flow batteries, is the core component of the all-vanadium redox flow battery system and is the place where electrochemical reactions occur and electrical energy is generated. The all-vanadium redox flow battery, also known as the Vanadium Redox Battery (VRB) and also called the vanadium battery, is a storage battery that realizes the reciprocating conversion of chemical energy into electrical energy through the valence state change of vanadium ions. It uses vanadium ion solutions with +4 and +5 valence states as the positive electrode active substances, and vanadium ion solutions with +2 and +3 valence states as the negative electrode active substances, which are respectively stored in their own electrolyte storage tanks. During the charge and discharge process, the positive and negative electrode electrolytes undergo oxidation-reduction reactions on both sides of the ion exchange membrane. At the same time, under the action of an external pump outside the stack, the electrolytes in the storage tanks are continuously fed into the positive electrode chamber and the negative electrode chamber to maintain the ion concentration and realize the charge and discharge of the battery.

[0003] The vanadium liquid battery stack is composed of multiple single all-vanadium redox flow batteries connected in series. Each single cell includes a positive electrode, a negative electrode, a separator, positive / negative electrodes, bipolar plates, positive electrode electrolyte, negative electrode electrolyte, etc. First, components required for the all-vanadium redox flow battery need to be prepared, including electrodes, bipolar plates, ion conductive membranes, end plates, flow guiding plates, current collecting plates, etc. The components such as electrodes, bipolar plates, and ion conductive membranes are assembled together according to specific sequences and process requirements to form a single cell. Multiple single cells are stacked together to form a stack. During the stacking process, the tightness and uniformity of the stack need to be controlled to ensure the performance and safety of the battery. The positive and negative electrodes of the stack are connected to an external circuit to form a complete battery system. The existing technology has the following problems: (1) Traditional electrolytes have problems of easy hydrolysis and precipitation at high temperatures and residual pollution of chemical reducing agents; (2) Traditional carbon felt electrodes have low activity, resulting in uneven distribution of electrolytes; (3) The traditional serpentine / parallel flow channels of bipolar plates have dead zones and large pressure drops. In summary, the above factors all lead to poor charge and discharge cycle performance and low current density of the vanadium liquid battery and the composed vanadium liquid battery stack. 5+ There are problems of easy hydrolysis and precipitation at high temperatures and residual pollution of chemical reducing agents; (2) Traditional carbon felt electrodes have low activity, resulting in uneven distribution of electrolytes; (3) The traditional serpentine / parallel flow channels of bipolar plates have dead zones and large pressure drops. In summary, the above factors all lead to poor charge and discharge cycle performance and low current density of the vanadium liquid battery and the composed vanadium liquid battery stack. Summary of the Invention

[0004] The present invention aims to provide a vanadium liquid battery, a battery stack and a manufacturing method thereof to provide a vanadium liquid battery with high charge and discharge cycle performance and high current density and the composed vanadium liquid battery stack.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A manufacturing method of a vanadium redox flow battery, which is assembled from a positive electrolyte, a negative electrolyte, electrodes and bipolar plates, includes the following steps: S1. Add phosphoric acid (H3PO4) and citric acid (molar ratio 1:2 - 4) to the positive electrolyte, and irradiate the negative electrolyte with ultraviolet light (intensity 50 - 60 mW / cm 2 ) for 60 - 80 min; S2. The electrode is a gradient electrode, with the surface layer: Bi@MnO2 heterojunction catalyst layer, thickness 50 ± 5 nm; the middle layer: vertically arranged graphene array, layer spacing 2 - 5 nm; the bottom layer: graphene aerogel diversion layer, porosity 90%, pore diameter 10 - 50 μm; the electrode is treated with argon plasma for 10 - 20 minutes and pulsed electrochemical oxidation is applied synchronously; S3: The flow channels of the bipolar plate are a three-level fractal tree structure, satisfying: the main channel width is 2 - 3 mm, the branch ratio coefficient is 0.7 - 0.8, the branch angle is 45 - 50°, and the surface of the flow channel is coated with a SiO2 / PTFE superhydrophobic coating.

[0007] The working principle and beneficial effects of the present invention:

[0008] Traditional electrolytes have problems such as easy hydrolysis precipitation at high temperatures and residual pollution of chemical reducing agents. By adding phosphoric acid (H3PO4) and citric acid (molar ratio 1:2 - 4) to the positive electrolyte, PO4 5+ forms a stable complex with V 3- (such as [VO2(H2PO4)2] 5+ ), and inhibits the hydrolysis reaction of V - through coordination bonds (V 5+ + H2O → VO(OH)3 5+ + H - ). Phosphate ions are preferentially adsorbed on the surface of vanadium ions at high temperatures (>40 °C), delaying precipitation kinetics. Citric acid (C6H8O7): As a radical scavenger, it blocks the chain oxidation reaction (such as the uncontrollable oxidation of V + initiated by ·OH radicals). 4+ →V 5+ ).

[0009] It forms a soluble complex with vanadium ions through carboxylic acid groups, reduces ionic activity, and inhibits crystallization. Synergistic effect: Phosphoric acid provides static complexation, and citric acid dynamically scavenges reactive oxygen species, inhibiting precipitation doubly; irradiate the negative electrolyte (V 2 solution) with ultraviolet light (intensity 50 - 60 mW / cm 4+ ) for 60 - 80 min, directly exciting the photoreduction reaction of V 4+ →V 3+ . Traditional oxalic acid reduction will generate CO2 and residual C2O4 2- , while photoreduction only requires H2O to participate, and the products are clean.

[0010] Functional design of the gradient electrode structure, surface layer (Bi@MnO2 heterojunction): Bi and MnO2 form a p-n heterojunction, and the built-in electric field accelerates charge separation (the Fermi level of Bi is higher than that of MnO2, electrons flow to Bi, and holes flow to MnO2). Bi catalyzes the V 2+ / V 3+ reaction, and MnO2 promotes the V 4+ / V 5+ reaction, reducing the overpotential. Middle layer (vertical graphene array): The vertical orientation reduces the electron transport path (conventional carbon felt is composed of random fibers, and electrons need to detour), and the in-plane conductivity is increased to 2000 S / m. The nanoscale layer spacing (2 - 5 nm) forms a quantum confinement effect, enhancing interfacial charge storage. Bottom layer (graphene aerogel): The hierarchical pores (10 - 50 μm macropores + 2 - 5 nm mesopores) achieve the synergy of Darcy flow and Knudsen diffusion, and the electrolyte penetration rate is increased by 3 times. Plasma-electrochemical synergistic activation Plasma treatment: High-energy Ar + bombards the carbon surface, etching amorphous carbon impurities and exposing the graphite crystal plane (the ID / IG ratio of Raman spectrum decreases from 1.2 to 0.8). Oxygen-containing functional groups (-COOH, -OH) are introduced to improve the wettability of the electrode (the contact angle decreases from 130° to 20°). Pulsed electrochemical oxidation: The pulsed current (1 kHz) forms an instantaneous high electric field in the double layer, preferentially oxidizing the defect sites to generate nano-pores (pore diameter 20 - 50 nm). The alternating action of Faraday current and non-Faraday current avoids excessive corrosion of the electrode.

[0011] Design a three-level fractal branch according to Murray's law (main channel 2.0 mm → secondary 1.4 mm → final 1.0 mm). The branch angle of 45° ensures a smooth transition of the streamline, reducing the generation of eddy currents (Reynolds number Re < 100, laminar flow state). The superhydrophobic surface reduces the electrolyte residue, avoiding the flow channel blockage caused by local deposition of vanadium ions.

[0012] This application realizes the long-term stability and high-purity regulation of the electrolyte through the coupling of phosphoric acid-citric acid synergistic complexation and photoreduction, providing technical support for high-temperature energy storage scenarios; the gradient electrode decouples the functions of "catalysis - conductivity - flow guiding", combines plasma-activated nanostructures, and breaks through the bottlenecks of low activity of traditional carbon felt and uneven electrolyte distribution; the fractal flow channel bionically optimizes the fluid path, and the superhydrophobic coating inhibits the electrolyte residue, solving the industry pain points of large pressure drop and easy blockage in traditional flow channels.

[0013] In some embodiments, the wavelength of the ultraviolet light is 254 nm.

[0014] In some embodiments, the pulse frequency is 1 kHz, and the argon plasma power is 100 W.

[0015] In some embodiments, after the surface of the flow channel in S3 is coated with a SiO2 / PTFE superhydrophobic coating, it is heat-treated at 150-200 °C to form a micro-nano composite structure.

[0016] In some embodiments, the width of the main channel is 2.0 mm, the branch ratio coefficient is 0.7, and the branch angle is 45°; the surface of the flow channel is coated with a SiO2 / PTFE superhydrophobic coating, and the contact angle ≥ 150°.

[0017] A vanadium redox flow battery stack is formed by connecting multiple vanadium redox flow batteries in series. Detailed implementation manners

[0018] The following is a further detailed description through specific implementation manners:

[0019] A manufacturing method of a vanadium redox flow battery is assembled from a positive electrode electrolyte, a negative electrode electrolyte, an electrode, and a bipolar plate.

[0020] Example 1: Add phosphoric acid (H3PO4) and citric acid (molar ratio 1:2) to the positive electrode electrolyte, 1.8 M V 5+ , 3.5 M H2SO4, 0.05 M H3PO4 + 0.1 M citric acid.

[0021] Control group 1: Traditional positive electrode electrolyte (without stabilizer), 1.8 M V 5+ , 3.5 M H2SO4,.

[0022] Control group 2: Add phosphoric acid (H3PO4) to the positive electrode electrolyte, 1.8 M V 5+ , 3.5 M H2SO4, 1.05 M H3PO4.

[0023] Control group 3: Add citric acid to the positive electrode electrolyte) 1.8 M V 5+ , 3.5 M H2SO4, 1.05 M citric acid.

[0024] Keep the example 1 and the control groups in an incubator at 60 °C, sealed and protected from light, and detect the precipitation to obtain the following data in Table 1:

[0025] Table 1

[0026]

[0027]

[0028] It can be concluded from Table 1 that the composite stabilizer of phosphoric acid and citric acid improves the high-temperature stability of the positive electrode electrolyte by more than 3 times. The traditional electrolyte has problems such as easy hydrolysis and precipitation of V5+ at high temperatures and residual pollution of chemical reducing agents. Add phosphoric acid (H3PO4) and citric acid (molar ratio 1:2-4) to the positive electrode electrolyte, PO4 3- and V5+ Form a stable complex (such as [VO2(H2PO4)2] - ), and inhibit the hydrolysis reaction of V 5+ through coordination bonds (V 5+ +H2O→VO(OH)3 - +H + ). Phosphate ions are preferentially adsorbed on the surface of vanadium ions at high temperatures (>40 °C), delaying the precipitation kinetics. Citric acid (C6H8O7), as a radical scavenger, blocks the chain oxidation reaction (such as the uncontrollable oxidation of V 4+ →V 5+ ) initiated by ·OH radicals. Soluble complexes are formed between vanadium ions and carboxylic acid groups to reduce the ion activity and inhibit crystallization. Synergistic effect: Phosphoric acid provides static complexation, and citric acid dynamically scavenges reactive oxygen species, and the two synergistically inhibit precipitation.

[0029] Example 2: The negative electrode electrolyte was irradiated with 254 nm ultraviolet light (intensity 50 mW / cm 2 ) for 3 min;

[0030] Control group 4: The negative electrode electrolyte was irradiated with 254 nm ultraviolet light (intensity 50 mW / cm 2 ) for 3 min;

[0031] Control group 5: The negative electrode electrolyte was irradiated with 254 nm ultraviolet light (intensity 50 mW / cm 2 ) for 90 min;

[0032] Control group 6: Traditional oxalic acid reduction method + 60-minute reaction.

[0033] The concentration of V3+ was measured using a UV-Vis spectrophotometer (UV-Vis, Agilent Cary 5000) to obtain the data in Table 2:

[0034] Table 2

[0035]

[0036] Irradiate the negative electrode electrolyte (V 2 solution) with ultraviolet light (intensity 50 - 60 mW / cm 4+ ) for 60 - 80 min to directly stimulate the photoreduction reaction of V 4+ →V 3+ . Compared with the traditional oxalic acid reduction of V 3+ , the conversion rate is higher.

[0037] Example 3: The electrode is a gradient electrode. Surface layer: Bi@MnO2 heterojunction catalyst layer with a thickness of 50 nm; middle layer: vertically aligned graphene array with a layer spacing of 2 nm; bottom layer: graphene aerogel flow guiding layer with a porosity of 90% and a pore diameter of 10 μm. The electrode is treated with argon plasma for 10 - 20 minutes and pulsed electrochemical oxidation is applied synchronously.

[0038] Graphene aerogel flow guiding layer: Disperse 1 wt% GO in deionized water, ultrasonic treat for 2 hours (power 300 W), add 0.1 M ascorbic acid, pour into a mold, seal and react at 180 °C for 12 hours to form a three-dimensional porous graphene hydrogel. Place the hydrogel at -50 °C for 24 hours, then transfer it to a freeze dryer (-80 °C, 0.1 Pa) and dry for 48 hours to obtain a graphene aerogel (porosity > 90%, pore diameter 10–50 μm).

[0039] Vertically aligned graphene array: Equipment: Plasma Enhanced Chemical Vapor Deposition (PE-CVD) Parameters: Substrate: graphene aerogel surface, Carbon source: methane (CH4), Plasma power: 500 W, Temperature: 800 °C, Time: 60 minutes.

[0040] Immerse the aerogel in 0.1 M Ni(NO3)2 solution for 10 minutes, dry it and reduce it in H2 / Ar (5% H2) (400 °C, 30 minutes) to form Ni nanoparticle catalysts. Grow graphene: CH4 flow rate: 50 sccm, H2 flow rate: 100 sccm, Pressure: 10 Pa. The height of the vertical graphene is 2 μm and the layer spacing is 2–5 nm (verified by TEM). Post-treatment: Etch away the Ni catalyst with 1 M FeCl3 solution to obtain a pure graphene array.

[0041] Bi@MnO2 heterojunction catalyst layer: Electrochemical deposition process

[0042] Electrolyte formula: 0.1 M Bi(NO3)3 + 0.05 M MnSO4 + 0.5 M H2SO4.

[0043] Deposition conditions: Three-electrode system: Working electrode (vertically aligned graphene array), Counter electrode (Pt sheet), Reference electrode (Ag / AgCl). Constant current mode: Current density 10 mA / cm 2 , time 5 minutes.

[0044] Reaction mechanism: Bi 3+ preferentially deposits to form nanoparticles (particle size 50–100 nm), and Mn 2+ is oxidized on its surface to form a MnO2 shell layer (thickness 5–10 nm), forming a core-shell structure.

[0045] Plasma treatment: Equipment is a radio frequency plasma cleaner (13.56 MHz). Parameters: Flow rate of Ar gas is 50 sccm, power is 100 W, treatment time is 10 minutes. Effect: Surface oxygen content increases from 5% to 15% (XPS analysis), and -COOH and -OH functional groups are generated. Pulsed electrochemical oxidation: Electrolyte: 0.5 M H2SO4. Parameters: Pulsed current density is 0.5 A / cm 2 , duty cycle is 50% (on for 1 ms, off for 1 ms), time is 10 minutes. Function: Etch nanoscale holes (hole diameter 20–50 nm, verified by SEM) on the surface of vertical graphene, and the specific surface area increases by 40%.

[0046] Control group 7: Traditional carbon felt

[0047] Tested by equipment: Micromeritics ASAP 2460 tests the surface area and tests the electrochemical activity (cyclic voltammetry, CV), electrolyte: 1.6 M V 3+ / V 4+ (negative electrode), 1.6 M V 4+ / V 5+ (positive electrode) Scanning rate: 10 mV / s, 25 °C. Obtain the data in Table 3:

[0048] Table 3

[0049]

[0050]

[0051] From the above data, it can be seen that (1) the specific surface area of the gradient electrode is significantly higher than that of the traditional carbon felt, about 6 times that of the traditional carbon felt. The larger the specific surface area, the larger the contact area between the electrode material and the electrolyte, which is beneficial to the progress of the electrochemical reaction; (2) the average pore diameter of the gradient electrode is significantly smaller than that of the traditional carbon felt. A smaller pore diameter usually means a higher pore density, which helps to improve the ion transport efficiency of the electrode, especially at high current densities. (3) The oxidation peak current density of the gradient electrode is significantly higher than that of the traditional carbon felt, about 4 times that of the traditional carbon felt, indicating that the gradient electrode has higher electrochemical activity in the oxidation reaction. (4) The reduction peak current density of the gradient electrode is also significantly higher than that of the traditional carbon felt, about 4 times that of the traditional carbon felt. This indicates that the gradient electrode also shows higher electrochemical activity in the reduction reaction.

[0052] It is shown that the gradient electrode (graphene + Bi@MnO2) is significantly superior to the traditional carbon felt in terms of specific surface area, average pore size, oxidation peak current density, and reduction peak current density. The high specific surface area and smaller pore size of the gradient electrode endow it with higher electrochemical activity, which can significantly increase the current density of oxidation and reduction reactions. The design of the gradient electrode (graphene + Bi@MnO2) exhibits obvious advantages in electrochemical performance and is suitable for application scenarios that require high electrochemical activity and efficient ion transport, such as high-performance batteries, supercapacitors, etc.

[0053] Example 4: The flow channels of the bipolar plate are of a three-level fractal tree structure, satisfying: the width of the main channel is 2 mm, the branch ratio coefficient is 0.7, the branch angle is 45°, the surface of the flow channels is coated with a SiO2 / PTFE superhydrophobic coating, and a micro-nano composite structure is formed by heat treatment at 150 °C.

[0054] Control group 8: Traditional serpentine flow channels, without coating

[0055] Control group 9: Three-level fractal tree structure, without coating.

[0056] The flow channel pressure drop test and the standard deviation of flow velocity (electrolyte flow velocity: 10 cm / s, viscosity 2.5 mPa·s) were carried out on Example 4, Control group 8, and Control group 9, and the following data in Table 4 were obtained:

[0057] Table 4

[0058]

[0059] Influence of the flow channel structure: The three-level fractal tree structure (Example 4 and Control group 9) performs better than the traditional serpentine flow channel (Control group 8) in terms of flow velocity uniformity, dead zone area, and pressure drop. This indicates that the fractal tree structure can effectively improve the flow distribution in the flow channel, reduce the dead zone, and lower the pressure drop.

[0060] Influence of the coating: Example 4 (with SiO2 / PTFE superhydrophobic coating) performs better than Control group 9 (without coating) in terms of flow velocity uniformity, dead zone area, and pressure drop. This indicates that the superhydrophobic coating can further improve the flow characteristics in the flow channel, reduce the dead zone, and lower the pressure drop.

[0061] Comprehensive performance: Example 4 (three-level fractal tree structure + superhydrophobic coating) performs best in all test indexes, with the lowest standard deviation of flow velocity, the smallest dead zone area, and the lowest pressure drop. This indicates that this design has significant advantages in improving the flow channel performance.

[0062] Example 5: Only the following changes are made to the traditional manufacturing method of the vanadium redox flow battery:

[0063] (1) Add phosphoric acid (H3PO4) and citric acid (molar ratio 1:2) to the positive electrolyte, and irradiate the negative electrolyte with ultraviolet light (intensity 50 mW / cm 2 ) for 60 min;

[0064] (2) The electrode is a gradient electrode. The surface layer: Bi@MnO2 heterojunction catalyst layer with a thickness of 50 nm; the middle layer: vertically aligned graphene array with a layer spacing of 2 nm; the bottom layer: graphene aerogel diversion layer with a porosity of 90% and a pore diameter of 10 μm; the electrode is treated with argon plasma for 10 minutes and pulsed electrochemical oxidation is applied synchronously;

[0065] (3) The flow channels of the bipolar plate are a three-level fractal tree structure, satisfying: the main channel width is 2 mm, the branch ratio coefficient is 0.7, the branch angle is 45°, and the surface of the flow channel is coated with a SiO2 / PTFE superhydrophobic coating.

[0066] Control Group 10: A vanadium redox flow battery obtained by the traditional manufacturing method of vanadium redox flow batteries.

[0067] Perform full-cell performance tests on Example 5 and Control Group 10 to obtain the following data in Table 5:

[0068] 1. Charge and discharge cycle (0.2C rate)

[0069] Test conditions: Stack scale: 5 kW / 20 kWh (40 single cells in series), Temperature: 25 ± 2 °C, Electrolyte flow rate: 15 L / min.

[0070] Table 5

[0071]

[0072]

[0073] By improving the positive electrolyte additive, negative electrolyte treatment, electrode structure, and bipolar plate flow channel design in Example 5, the energy efficiency and capacity retention rate of the vanadium redox flow battery are significantly improved. Compared with the traditional manufacturing method of vanadium redox flow batteries (Control Group 10), Example 5 exhibits more excellent electrochemical performance and cycling stability during long-term cycling. This indicates that the improved method adopted in Example 5 has significant advantages in improving the performance and lifespan of vanadium redox flow batteries and is suitable for applications in scenarios requiring high energy efficiency and long cycling lifespan.

[0074] 2. Peak power density (polarization curve)

[0075] Conditions: SOC = 50%, Electrolyte flow rate: 20 cm / s, The results are as follows in Table 6:

[0076] Table 6

[0077]

[0078] Example 5 significantly improved the power density and voltage performance of the vanadium redox flow battery by improving the positive electrolyte additive, negative electrolyte treatment, electrode structure, and bipolar plate flow channel design. Compared with the traditional manufacturing method of vanadium redox flow battery (Control Group 10), Example 5 showed more excellent electrochemical performance at different current densities. This indicates that the improvement method adopted in Example 5 has significant advantages in improving the power output and electrochemical performance of the vanadium redox flow battery and is suitable for application scenarios that require high power density and high voltage performance.

Claims

1. A method for manufacturing a vanadium liquid battery, characterized in that: The process is assembled from positive electrode electrolyte, negative electrode electrolyte, electrodes and bipolar plates, and includes the following steps: S1. Phosphoric acid (H3PO4) and citric acid (molar ratio 1:2-4) are added to the positive electrolyte, and the negative electrolyte is exposed to ultraviolet light (intensity 50-60 mW / cm 2 ) irradiating the negative electrode electrolyte for 60 to 80 minutes; S2, the electrode is a gradient electrode, the surface layer: Bi@MnO2 heterojunction catalyst layer, thickness 50±5nm; Middle layer: vertically arranged graphene array, with an interlayer spacing of 2 to 5 nm; Bottom layer: graphene aerogel conductive layer, porosity 90%, pore size 10-50 μm; the electrode is treated with argon plasma for 10-20 minutes, and pulse electrochemical oxidation is applied synchronously; S3: The flow channel of the bipolar plate is a three-level fractal tree structure, which meets the following requirements: main channel width 2-3 mm, branch ratio coefficient 0.7-0.8, branch angle 45-50°, and the flow channel surface is coated with SiO2 / PTFE super-hydrophobic coating.

2. The method for making a vanadium liquid battery according to claim 1, characterized in that: The wavelength of the ultraviolet light is 254 nm.

3. The method for manufacturing the vanadium liquid battery according to claim 2, characterized in that: The pulse frequency was 1 kHz and the argon plasma power was 100 W.

4. The method for manufacturing the vanadium liquid battery according to claim 3, characterized in that: The surface of the flow channel in S3 is coated with SiO2 / PTFE super-hydrophobic coating and then heat treated at 150-200°C to form a micro-nano composite structure.

5. The method for manufacturing the vanadium liquid battery according to claim 4, characterized in that: The main channel width is 2.0 mm, the branch ratio coefficient is 0.7, and the branch angle is 45°; the channel surface is coated with a SiO2 / PTFE super-hydrophobic coating with a contact angle ≥150°.

6. A vanadium liquid battery stack, formed by connecting a plurality of vanadium liquid batteries prepared in claims 1 to 4 in series.

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