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CN-122010822-A - Folding viologen, preparation method thereof and application of folding viologen in water-based flow battery

CN122010822ACN 122010822 ACN122010822 ACN 122010822ACN-122010822-A

Abstract

The invention relates to a folding viologen compound, a preparation method thereof and application thereof in an aqueous flow battery. The invention provides and synthesizes a double-purple-essence compound with a folding space conformation for the first time. The molecule is covalently connected with two viologen units through a flexible bridging group, so that the molecule can perform high-efficiency two-electron storage, and simultaneously can perform high-efficiency reversible two-electron reaction, thereby being beneficial to improving the volume energy density of the battery. More importantly, in the two-electron reduction state, the free radicals generated on the two viologen units can be in intramolecular or intermolecular interaction (such as formation of free radical-free radical bond) through spatial proximity, so that the reactivity of the reduction state substance is obviously reduced, the reaction rate of the reduction state substance and oxygen is slowed down, and the stability of the electrolyte in the air is fundamentally improved. The preparation method provided by the invention has the advantages of simple steps, high yield, high product purity and good application prospect.

Inventors

  • LIANG ZHENXING
  • LIU YUFENG
  • FU ZHIYONG
  • HUANG MINGBAO

Assignees

  • 华南理工大学

Dates

Publication Date
20260512
Application Date
20260121

Claims (10)

  1. 1. A folding viologen, characterized by a structural formula: Wherein X represents a C3-C15 alkylene group and contains at most one first substituent, which is one of an alkyl group, an alkoxy group, a hydroxyl group, a carboxyl group, a quaternary ammonium group or a halogen, or X represents a C3-C8 carbon chain containing 1 to 6 ether groups or imino groups, the number of which is not more than the number of carbon atoms; r 1 -R 16 is independently selected from hydrogen or C1-C6 alkyl; R 17 -R 18 is independently selected from at least one of C1-C10 alkyl, C1-C10 alkyl with the tail end substituted by a second substituent or C1-C10 alkyl containing a branched chain, wherein the second substituent is one of hydroxyl, carboxyl, quaternary ammonium group or sulfonic acid group, and the branched chain is one of alkyl, hydroxyl, carboxyl, quaternary ammonium group or sulfonic acid group; Y - represents an anion selected from at least one of chloride, bromide, iodide, nitrate, bisulfate and hexafluorophosphate, and b is an integer of 1 to 9. a is an integer of 1 to 9.
  2. 2. The folded viologen according to claim 1, wherein said X represents a C3-C6 alkylene group and comprises a first substituent being one of an alkyl group, an alkoxy group, a hydroxyl group, a carboxyl group, a quaternary ammonium group, or a halogen, or wherein said X represents a C3-C6 carbon chain and said carbon chain comprises 1-6 ether groups or imino groups, said ether groups or imino groups having no more than carbon atoms.
  3. 3. The folded viologen of claim 1, wherein said Y - is selected from at least one of chloride, bromide, iodide, nitrate.
  4. 4. The folded viologen of claim 1 wherein said R 17 -R 18 are independently selected from one of the following structures: 、 、 、 、 、 、 、 、 、 、 wherein n=1-10, m=0-5.
  5. 5. A method for preparing the folded viologen as claimed in any one of claims 1 to 4, comprising the steps of: Adding the 4, 4-bipyridine derivative into an organic solvent, then adding a bridging group, and reacting to obtain a folded viologen intermediate; then adding a blocking agent into the folded viologen intermediate, and reacting to obtain the folded viologen; the end capping agent is halide of the R 17 -R 18 structure; the structural formula of the 4, 4-bipyridine derivative is shown as follows: wherein R 1 -R 8 is independently selected from hydrogen or C1-C6 alkyl; the bridging group comprises at least one of the following structures: 、 、 、 、 、 、 、 、 Wherein d=1 to 6, y 1 、Y 2 is independently selected from one of chlorine, bromine, iodine atoms; The structural formula of the folded viologen intermediate is shown as follows: Wherein R 1 -R 16 is independently selected from hydrogen or C1-C6 alkyl.
  6. 6. The method for preparing folded viologen according to claim 5, wherein said folded viologen is prepared in other anionic form by ion exchange method, wherein said Y - is at least one selected from the group consisting of chloride, bromide, iodide, nitrate, hydrogen sulfate and hexafluorophosphate.
  7. 7. The method for preparing folding viologen according to claim 5, wherein said organic solvent is at least one of acetonitrile, N-dimethylformamide, toluene, 1, 4-dioxane and dimethyl sulfoxide.
  8. 8. The method for preparing the folded viologen according to claim 5, wherein the reaction temperature of the 4, 4-bipyridine derivative and the bridging group is 75-90 ℃, the reaction time is 24-120h, the reaction temperature of the folded viologen intermediate and the end capping agent is 80-150 ℃, and the reaction time is 24-120h.
  9. 9. A negative electrode electrolyte of an aqueous flow battery, comprising the folded viologen of any one of claims 1-4.
  10. 10. An aqueous flow battery comprising the negative electrode electrolyte of claim 9.

Description

Folding viologen, preparation method thereof and application of folding viologen in water-based flow battery Technical Field The invention relates to the technical field of electrochemical energy storage and flow batteries, in particular to a folding viologen compound, a preparation method thereof and application of the folding viologen compound serving as a negative electrode active material in an aqueous organic flow battery. Background The energy storage technology is a novel 'ballast stone' for safely, efficiently and stably operating an electric power system, and provides strategic support for realizing a 'double-carbon' target. The electrochemical energy storage technology has the characteristics of high flexibility, quick response time and the like, and has wide application prospect in the field of large-scale energy storage. In electrochemical energy storage, the flow battery has the advantages of capacity and power decoupling, high safety and the like, and is used as a medium-long-time safe energy storage technology, and commercialized demonstration is gradually carried out in recent years. The water-based organic flow battery has the advantages of wide sources of electroactive materials, low cost, easy acquisition, easy energy level regulation, good electrochemical reversibility and the like, and has great commercialization prospect. The viologen electroactive molecule has good water solubility, high electrochemical reversibility and wide attention for near neutral pH environment, and is an electroactive organic molecule with great application prospect. However, the reduced viologen is a high-activity Shan Ziyou group/diradical, which is attacked by solvent and oxygen, and the stability is threatened, so that the flow battery cannot stably operate under the air. Therefore, the development of air-tolerant viologen-based electrolytes is an important ring for pushing viologen-based aqueous organic flow batteries towards practical applications. Disclosure of Invention Based on the above, the invention aims to provide a folding viologen, a preparation method thereof and application thereof in a water-based flow battery, wherein two viologen units are covalently connected at two ends of a flexible bridging group (X), so that a folding space conformation is constructed, the reaction rate of the folding viologen with oxygen is effectively slowed down through the molecular design, and the air stability of electrolyte is fundamentally improved. First aspect: A folding viologen has a structural general formula: Wherein X represents a C3-C15 alkylene group and contains at most one first substituent, which is one of an alkyl group, an alkoxy group, a hydroxyl group, a carboxyl group, a quaternary ammonium group or a halogen, or X represents a C3-C8 carbon chain containing 1 to 6 ether groups or imino groups, the number of which is not more than the number of carbon atoms; r 1-R16 is independently selected from hydrogen or C1-C6 alkyl; R 17-R18 is independently selected from at least one of C1-C10 alkyl, C1-C10 alkyl with the tail end substituted by a second substituent or C1-C10 alkyl containing a branched chain, wherein the second substituent is one of hydroxyl, carboxyl, quaternary ammonium group or sulfonic acid group, and the branched chain is one of alkyl, hydroxyl, carboxyl, quaternary ammonium group or sulfonic acid group; Y - represents an anion selected from at least one of chloride, bromide, iodide, nitrate, bisulfate and hexafluorophosphate, and b is an integer of 1 to 9. a is an integer of 1 to 9. The invention provides and synthesizes a double-purple-essence compound with a folding space conformation for the first time. The molecule is covalently connected with two viologen units through a flexible bridging group (X), so that the molecule can perform high-efficiency two-electron storage, and simultaneously can perform high-efficiency reversible two-electron reaction, thereby being beneficial to improving the volume energy density of the battery. More importantly, in the two-electron reduction state, the free radicals generated on the two viologen units can be in intramolecular or intermolecular interaction (such as formation of free radical-free radical bond) through spatial proximity, so that the reactivity of the reduction state substance is obviously reduced, the reaction rate of the reduction state substance and oxygen is slowed down, and the stability of the electrolyte in the air is fundamentally improved. Based on the unique structure, the water-based flow battery negative electrode electrolyte prepared by the folding viologen compound successfully solves the bottleneck problem that the traditional viologen-based electrolyte is unstable in air, so that the battery can stably operate for a long time under a non-strict inert atmosphere condition (such as air), and the system packaging and operation and maintenance cost is reduced. Therefore, the folding viologen compound provides an innovativ