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CN-122025687-A - All-vanadium redox flow battery bipolar plate and preparation method thereof

CN122025687ACN 122025687 ACN122025687 ACN 122025687ACN-122025687-A

Abstract

The invention relates to the technical field of manufacturing of key components of all-vanadium redox flow batteries, in particular to an all-vanadium redox flow battery bipolar plate and a preparation method thereof, which are used for solving the problem that the mechanical property, corrosion resistance and conductivity of the existing all-vanadium redox flow battery bipolar plate are poor and seriously affecting the overall performance of an all-vanadium redox flow battery. Moreover, the invention has low cost and simple process, is easy to realize batch production and is suitable for industrialized popularization.

Inventors

  • ZHANG JIANJUN
  • ZHANG YUJING
  • Mai Hanquan
  • LI CHANGHE

Assignees

  • 广东中科天钒储能科技有限公司

Dates

Publication Date
20260512
Application Date
20260129

Claims (10)

  1. 1. The all-vanadium redox flow battery bipolar plate is characterized by sequentially comprising a bottom carbon base layer, a middle reinforcing layer and a top carbon base layer from bottom to top, wherein the three-layer structure is formed into a whole through extrusion and solidification; The bottom carbon-based layer is formed by solidifying carbon-based coating slurry doped with etched polytetrafluoroethylene particles; the middle reinforcing layer is a graphite-carbon nano tube composite board embedded with a red copper net, and the graphite-carbon nano tube composite board is formed by curing composite slurry; The top carbon-based layer is formed by solidifying carbon-based coating slurry; the carbon-based coating slurry comprises the following components in parts by mass: 40-60 parts of expandable graphite powder, 8-15 parts of carbon black, 15-25 parts of epoxy resin, 5-8 parts of curing agent and 0.6-2.2 parts of polyfluoropyridine cationic compound; The composite slurry comprises the following components in parts by mass: 65-90 parts of flake graphite powder, 2-3 parts of carbon nano tubes, 10-20 parts of phenolic resin and 1-3 parts of silane coupling agent KH-550.
  2. 2. The all-vanadium redox flow battery bipolar plate of claim 1, wherein the mass of etched polytetrafluoroethylene particles is 5-8% of the mass of the carbon-based coating slurry.
  3. 3. The all-vanadium redox flow battery bipolar plate according to claim 1, wherein etched polytetrafluoroethylene particles are obtained by performing argon plasma etching treatment on polytetrafluoroethylene particles with the particle size of 1mm for 3-5min under the conditions of the frequency of 40kHz and the pressure of 50 Pa.
  4. 4. The all-vanadium redox flow battery bipolar plate according to claim 1 is characterized in that the expansion ratio of the expandable graphite powder is more than or equal to 200 times, the carbon black is SP conductive carbon black, the epoxy resin is E-51, and the curing agent is D400 polyether amine curing agent.
  5. 5. The all-vanadium redox flow battery bipolar plate according to claim 1, wherein the particle size of the crystalline flake graphite powder is 50-100 μm, the length-diameter ratio of the carbon nanotubes is 100-200, and the phenolic resin is phenolic resin 2402.
  6. 6. The all-vanadium redox flow battery bipolar plate according to claim 1, wherein the polyfluoropyridine cationic compound is prepared by the following steps: Step a1, stirring and reacting dimethyl 5-bromoisophthalic acid, pyridine-4-boric acid, potassium carbonate, tetra (triphenylphosphine) palladium, deionized water and tetrahydrofuran, cooling a reaction product after the reaction is finished, pouring the reaction product into distilled water, extracting, drying an extract with anhydrous magnesium sulfate, vacuum-filtering, and rotationally evaporating filtrate to obtain a diester pyridine compound; step a2, stirring diester pyridine compound, dimethyl 5-bromoisophthalic acid, triethylamine and tetrahydrofuran for reaction, cooling reaction products after the reaction is finished, vacuum filtering, pouring filtrate into concentrated hydrochloric acid, centrifuging, washing and drying precipitate to obtain a tetracarboxylic pyridine cation compound; And a3, stirring and reacting the tetracarboxyl pyridine cationic compound, perfluorohexyl ethyl alcohol, p-toluenesulfonic acid and toluene, cooling a reaction product after the reaction is finished, washing, drying by using anhydrous magnesium sulfate, vacuum filtering, and rotationally evaporating filtrate to obtain the polyfluoropyridine cationic compound.
  7. 7. The all-vanadium flow battery bipolar plate according to claim 6, wherein the dosage ratio of dimethyl 5-bromoisophthalate, pyridine-4-boric acid, potassium carbonate, tetrakis (triphenylphosphine) palladium, deionized water, and tetrahydrofuran in step a1 is 10mmol:11-13mmol:20-25mmol:0.4-0.5g:3-5ml:50-55mL.
  8. 8. The all-vanadium redox flow battery bipolar plate according to claim 6, wherein the dosage ratio of the diester-based pyridine compound, the dimethyl 5-bromoisophthalate, the triethylamine and the tetrahydrofuran in the step a2 is 10 mmol/20-25 mmol/80-90 mL, and the mass fraction of the concentrated hydrochloric acid is 36-38%.
  9. 9. The bipolar plate of an all-vanadium redox flow battery according to claim 6, wherein the amount of the tetracarboxylpyridine cationic compound, perfluorohexyl ethyl alcohol, p-toluene sulfonic acid, and toluene in step a3 is 10mmol:40mmol:0.3-0.5g:100-120mL.
  10. 10. A method for preparing the bipolar plate of the all-vanadium redox flow battery as set forth in any one of claims 1 to 9, comprising the steps of: Firstly, preprocessing a red copper net, namely placing the red copper net with 20 meshes in dilute sulfuric acid with the mass fraction of 10% for soaking for 5min to remove an oxide film, then flushing the red copper net with deionized water to be neutral, and then placing the red copper net in a vacuum drying oven for drying for 30-40min at the temperature of 60-70 ℃ for later use; Weighing flake graphite powder, carbon nano tubes, phenolic resin and silane coupling agent KH-550 according to mass parts, adding the flake graphite powder and the carbon nano tubes into a high-speed mixer, mixing for 20min under the condition of stirring speed of 1500r/min, adding the phenolic resin and the silane coupling agent, and continuously mixing for 30min to obtain composite slurry; Step three, pressing and solidifying, namely flatly laying the pretreated red copper net with 20 meshes in a mould, uniformly filling the composite slurry into grids of the red copper net, and rolling and flattening by a press roller, wherein the filling thickness is controlled to be 2-4mm; Weighing expandable graphite powder, carbon black, epoxy resin, curing agent and polyfluoropyridine cationic compound according to parts by mass, mixing, adding into a planetary ball mill, and ball milling for 60min under the condition of ball milling speed of 300r/min to obtain carbon-based coating slurry; Step five, preparing bottom carbon-based coating slurry, namely adding the carbon-based coating slurry and etched polytetrafluoroethylene particles into a high-speed mixer, and mixing for 10min under the condition of stirring speed of 500r/min to obtain bottom carbon-based coating slurry; step six, paving a bottom carbon-based coating slurry uniformly in a lower die cavity of a hydraulic forming machine, wherein the paving thickness is 1-2mm, and the surface is ensured to be smooth; Positioning the middle reinforcing layer, namely horizontally placing the graphite-carbon nano tube composite board embedded with the red copper net on the bottom carbon-based coating slurry, ensuring that the center of the middle reinforcing layer is aligned with the center of a die cavity, and reserving a slurry coating space with the periphery of 5-7.5 mm; Step eight, paving a top carbon base layer, namely uniformly paving carbon-based coating slurry on the graphite-carbon nano tube composite board embedded with the red copper net, wherein the paving thickness is 1-2mm, and covering the whole middle reinforcing layer and the reserved space; Step nine, extrusion solidification, namely starting a hydraulic forming machine, applying pressure of 10-15MPa, simultaneously raising the temperature of a die cavity to 150 ℃, preserving heat for 3 hours, carrying out compression heating solidification, naturally cooling to room temperature after solidification is completed, and demoulding to obtain a bipolar plate rough blank; And step ten, post-treatment, namely mechanically polishing the cladding edge of the rough blank of the bipolar plate to ensure that the surface roughness Ra is less than or equal to 0.1 mu m, processing the edge into a round angle with the radius of 2-3mm, and then cutting the polished bipolar plate into a specified size according to the battery assembly requirement to obtain the bipolar plate of the all-vanadium redox flow battery.

Description

All-vanadium redox flow battery bipolar plate and preparation method thereof Technical Field The invention relates to the technical field of manufacturing of key components of an all-vanadium redox flow battery, in particular to an all-vanadium redox flow battery bipolar plate and a preparation method thereof. Background All-Vanadium Redox Flow Batteries (VRFB) have become one of core technologies in the field of large-scale energy storage by virtue of the advantages of high solubility of active substances, stable electrolyte circulation, no cross contamination in charge and discharge processes and the like. The bipolar plate is used as a framework and a nerve of VRFB, not only needs to bear an electrode structure and separate positive and negative electrolyte, but also efficiently conducts electrons and resists corrosion of strong acid vanadium electrolyte, and the performance of the bipolar plate directly determines the power density and the cycle life of the battery. The existing mainstream bipolar plate material has obvious short plates, such as a pure graphite bipolar plate, which has excellent conductivity, high brittleness, poor impact resistance, easy crack occurrence in the processing process and difficult control of flatness of a large-size polar plate, a metal base bipolar plate which has outstanding mechanical properties, easy anodic dissolution in sulfuric acid electrolyte, and capacity attenuation of a battery caused by corrosion products entering the electrolyte, and a traditional carbon base composite material which has both partial conductivity and corrosion resistance and often has increased resistance due to overhigh content of a binder or has fluctuation of mechanical properties due to uneven dispersion of a reinforcing phase. Therefore, the development of the all-vanadium redox flow battery bipolar plate and the preparation method thereof have important practical significance. Disclosure of Invention In order to overcome the technical problems, the invention aims to provide an all-vanadium redox flow battery bipolar plate and a preparation method thereof, which solve the problems that the mechanical property, corrosion resistance and conductivity of the existing all-vanadium redox flow battery bipolar plate are poor and the overall performance of the all-vanadium redox flow battery is seriously affected. The aim of the invention can be achieved by the following technical scheme: in a first aspect, the application provides an all-vanadium redox flow battery bipolar plate, which sequentially comprises a bottom carbon-based layer, a middle reinforcing layer and a top carbon-based layer from bottom to top, wherein the three-layer structure is formed into a whole through extrusion and solidification; The bottom carbon-based layer is formed by solidifying carbon-based coating slurry doped with etched polytetrafluoroethylene particles; the middle reinforcing layer is a graphite-carbon nano tube composite board embedded with a red copper net, and the graphite-carbon nano tube composite board is formed by curing composite slurry; The top carbon-based layer is formed by solidifying carbon-based coating slurry; the carbon-based coating slurry comprises the following components in parts by mass: 40-60 parts of expandable graphite powder, 8-15 parts of carbon black, 15-25 parts of epoxy resin, 5-8 parts of curing agent and 0.6-2.2 parts of polyfluoropyridine cationic compound; The composite slurry comprises the following components in parts by mass: 65-90 parts of flake graphite powder, 2-3 parts of carbon nano tubes, 10-20 parts of phenolic resin and 1-3 parts of silane coupling agent KH-550. As a preferred embodiment of the invention, the mass of the etched polytetrafluoroethylene particles is 5-8% of the mass of the carbon-based coating slurry, wherein the etched polytetrafluoroethylene particles can form a distributed micro-channel structure. As a preferred implementation mode of the invention, the etched polytetrafluoroethylene particles are obtained by carrying out argon plasma etching treatment on polytetrafluoroethylene particles with the particle size of 1mm for 3-5min under the conditions of the frequency of 40kHz and the pressure of 50Pa, and the interface binding force between the etched polytetrafluoroethylene particles and the coating can be improved after etching, so that the particles are prevented from falling off and blocking the flow channel in the using process. As a preferable implementation mode of the invention, the expansion ratio of the expandable graphite powder is more than or equal to 200 times, the carbon black is SP conductive carbon black, the epoxy resin is E-51, and the curing agent is D400 polyether amine curing agent. As a preferred embodiment of the invention, the particle size of the crystalline flake graphite powder is 50-100 mu m, the length-diameter ratio of the carbon nano tube is 100-200, and the phenolic resin is phenolic resin 2402. As a preferred embodime