阅读说明：本技术 一种基于聚吡咯喹喔啉负极的全水系混合液流电池及制备方法 (Polypyrrole-quinoxaline-negative-electrode-based all-water-system mixed flow battery and preparation method thereof ) 是由 许娟 王宾宾 曹剑瑜 陈智栋 于 2019-11-06 设计创作，主要内容包括：本发明属于新能源材料领域,具体涉及一种基于聚吡咯喹喔啉负极的全水系混合液流电池及制备方法。制备方法包括以下步骤：首先将吡咯官能团与喹喔啉接枝,通过溴氧化法制备具有共轭结构、低负电位和优异导电性的固态聚吡咯喹喔啉负极；采用碱性水系电解液,再将亚铁氰化钾溶解在碱性水系电解液中,作为液态正极；将正极和负极组装成全水系混合液流电池。本专利设计的单液流电池兼具了全水系液流电池和固体电池的优点,具有成本低、结构简单、高能量密度、高循环稳定性的优点,在未来的大规模储能应用上具有广阔的前景。(The invention belongs to the field of new energy materials, and particularly relates to a polypyrrole-quinoxaline-negative-electrode-based all-water-system mixed liquid flow battery and a preparation method thereof. The preparation method comprises the following steps: firstly, a pyrrole functional group is grafted with quinoxaline, and a solid polypyrrole quinoxaline negative electrode with a conjugated structure, low negative potential and excellent conductivity is prepared by a bromine oxidation method; adopting alkaline water-based electrolyte, and dissolving potassium ferrocyanide in the alkaline water-based electrolyte to obtain a liquid anode; and assembling the positive electrode and the negative electrode into the full-water mixed liquid flow battery. The single flow battery designed by the patent has the advantages of both an all-water-system flow battery and a solid battery, has the advantages of low cost, simple structure, high energy density and high cycle stability, and has wide prospect in future large-scale energy storage application.)

1. The battery is characterized in that the battery takes a polypyrrole-quinoxaline conducting polymer with low negative potential as a negative electrode, water-soluble potassium ferrocyanide with high positive potential as a liquid flow positive electrode, and KOH aqueous solution as electrolyte of the positive electrode and the negative electrode.

2. The all-water mixed liquid flow battery based on the polypyrrole quinoxaline negative electrode according to the claim 1, wherein the structure of the polypyrrole quinoxaline is shown as the following formula:

3. The all-water mixed liquid flow battery based on the polypyrrole quinoxaline negative electrode according to the claim 1, wherein the polypyrrole quinoxaline is prepared by taking a pyrrole quinoxaline monomer as a raw material and passing Br₂And (3) synthesizing polypyrrole quinoxaline by free radical initiated polymerization.

4. The all-water mixed liquid flow battery based on the polypyrrole quinoxaline negative electrode according to the claim 3, wherein the pyrrole quinoxaline monomer is uniformly dispersed in DMF solvent, and Br is slowly dropped at 60 ℃₂By Br₂And (4) carrying out free radical initiated polymerization to synthesize the polypyrrole quinoxaline.

5. The all-aqueous mixed liquid flow battery based on polypyrrole quinoxaline negative electrode according to claim 3, characterized in that the molar ratio of bromine to pyrrole quinoxaline monomer is 1:5-2: 1.

6. The all-water-system mixed liquid flow battery based on the polypyrrole quinoxaline negative electrode according to claim 3, wherein the pyrrole quinoxaline monomer is synthesized by a solvothermal method by taking amino quinoxaline and 2, 5-dimethoxy tetrahydrofuran as raw materials, wherein the amino quinoxaline is 6-amino quinoxaline, 2-amino-3-chloro quinoxaline, 2, 3-diamino quinoxaline or 5-amino quinoxaline.

7. The all-water mixed flow battery based on the polypyrrole quinoxaline negative electrode according to claim 6, wherein the synthesized pyrrole quinoxaline monomer is specifically: adding aminoquinoxaline, 2, 5-dimethoxytetrahydrofuran and catalyst iodine into DMF and H₂O, the mixture was stirred under reflux for 5h under an oil bath at 130 ℃.

8. The polypyrrole quinoxaline negative electrode-based all-water system mixed liquid flow battery according to claim 7, wherein the molar ratio of the aminoquinoxaline and the 2, 5-dimethoxy tetrahydrofuran is 5:1 to 1:5, and the total molar ratio of the catalyst iodine to the aminoquinoxaline and the 2, 5-dimethoxy tetrahydrofuran is 0.01:1 to 0.05: 1.

9. A method for preparing a polypyrrole-quinoxaline-negative-electrode-based all-water-system mixed liquid flow battery according to any one of claims 1 to 8, wherein the method comprises the following steps:

(1) the method comprises the following steps of grafting a pyrrole functional group and quinoxaline to obtain a pyrrole quinoxaline monomer, and preparing a solid polypyrrole quinoxaline negative electrode material with a conjugated structure, a low negative potential and excellent conductivity by the monomer through a bromine oxidation method;

(2) adopting alkaline water-based electrolyte; dissolving potassium ferrocyanide in the alkaline aqueous electrolyte to form a liquid anode; and assembling the positive electrode and the negative electrode into the water-based mixed liquid flow battery.

10. The preparation method of the full-water mixed liquid flow battery based on the polypyrrole-quinoxaline negative electrode according to the claim 9, is characterized in that: the pH value of the alkaline electrolyte is 7-14.

Technical Field

The invention belongs to the field of new energy materials, and particularly designs a polypyrrole-quinoxaline negative electrode-based all-water mixed liquid flow battery and a preparation method thereof.

Background

Redox flow batteries (abbreviated as flow batteries), as a new electrochemical energy storage technology, were proposed by the united states space and aviation administration (NASA) in the last 70 th century, and the system thereof consists of electrochemical cells, storage tanks and pumps driving electrolyte solutions to circulate in the cells, and can provide reversible conversion between electrical energy and chemical energy. Because the positive and negative electrolytes are separately circulated, the redox flow battery provides chemical energy by the electrochemical active material dissolved in the liquid, and has the advantages of extremely long cycle life, difficult self-discharge and the like.

Flow batteries are classified into total flow batteries and mixed flow batteries. Full flow batteries, such as all vanadium, hydrogen-bromine, anthraquinone-bromine, etc., have the advantage of long cycle life, but because of the limited solubility of the anode and cathode electrode materials, the full flow batteries have lower charge-discharge potential and energy density. One pole of the mixed liquid flow battery adopts a solid electrode, and the other pole adopts a liquid redox couple, so that the design can take the advantages of the secondary battery and the redox flow battery into consideration, and has important research significance.

The research on such hybrid energy storage systems as hybrid flow batteries is still in the beginning stage at home and abroad, and a small amount of research is mostly focused on non-aqueous systems at present. For water-based electrode materials, zinc-bromine, zinc-iodine, zinc-tetramethylpiperidine oxynitride flow batteries and the like are mainly researched, however, bromine in the water-based electrode materials is toxic and highly corrosive, and zinc is easy to generate dendrite, so that the self-discharge is serious and the efficiency is low.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the invention provides a water system mixed liquid flow battery based on a polypyrrole-quinoxaline negative electrode, aiming at solving the problems of low charge-discharge potential and low energy storage of the current flow battery. Like the rest of chemical energy sources, the electrochemical performance of a flow battery depends on the performance of cathode and anode electrode materials. In view of adjustable electrode potential and high theoretical energy density of organic polymer, the invention provides a full-water system mixed single flow battery which is constructed by taking a polypyrrole-quinoxaline solid material as a negative electrode and taking high-water-solubility potassium ferrocyanide as a positive electrode.

The invention aims to synthesize a conductive polymer grafted quinoxaline material with a conjugated structure, and apply the quinoxaline material to an aqueous mixed liquid flow battery. In order to achieve the purpose, the invention provides a synthesis method of a polypyrrole-quinoxaline electrode material, and provides an aqueous mixed liquid flow battery based on a polypyrrole-quinoxaline negative electrode and a ferrous potassium cyanide metal organic complex liquid flow positive electrode. The polypyrrole quinoxaline material provided by the invention has a conjugated structure, is high in electron transmission rate and conductivity, integrates the advantages of a solid-state battery and a flow battery, has the advantages of low cost, simple structure, high energy density and high cycle stability, and has a wide prospect in future large-scale energy storage application. The aqueous electrolyte has higher conductivity than the organic electrolyte.

The technical scheme adopted by the invention for solving the technical problems is as follows: a polypyrrole-quinoxaline-negative-electrode-based all-water-system mixed liquid flow battery takes a low-negative-potential polypyrrole-quinoxaline conducting polymer as a negative electrode, a high-positive-potential water-soluble potassium ferrocyanide as a liquid flow positive electrode, and a KOH aqueous solution as an electrolyte of the positive electrode and the negative electrode.

The polypyrrole-quinoxaline conductive polymer with low negative potential is polypyrrole-grafted quinoxaline; the synthesis of the polypyrrole quinoxaline takes pyrrole quinoxaline monomer as raw material, the pyrrole quinoxaline is uniformly dispersed in DMF solvent, and Br is slowly dropped at 60 DEG C₂By Br₂And (4) carrying out free radical initiated polymerization to synthesize the polypyrrole quinoxaline. Wherein the molar ratio of bromine to the pyrrole quinoxaline monomer is 1:5-2: 1.

Wherein, the synthesis of the pyrrole quinoxaline monomer is to synthesize the pyrrole quinoxaline by taking aminoquinoxaline (specifically 6-aminoquinoxaline, 2-amino-3-chloroquinoxaline, 2, 3-diaminoquinoxaline or 5-aminoquinoxaline) as a raw material and 2, 5-dimethoxytetrahydrofuran through a solvothermal method. The molar ratio of aminoquinoxaline to 2, 5-dimethoxytetrahydrofuran is 5:1-1:5, and the molar ratio of catalyst iodine to the total of the two raw materials is 0.01:1-0.05: 1.

The specific synthetic process of the pyrrole quinoxaline monomer is as follows: firstly, aminoquinoxaline, 2, 5-dimethoxytetrahydrofuran and iodine are dissolved in a mixed solution of DMF and water together, stirred for 2 hours, placed in a reaction kettle and heated at 130 ℃ for 5 hours. Adding distilled water, and standing for 12 hr to obtain precipitate. Filtering, vacuum drying and other steps to obtain the product.

The specific synthetic process of the polypyrrole quinoxaline taking the 6-aminoquinoxaline as the monomer is as follows:

wherein the value of n is between 40 and 210.

The construction steps of the full-water mixed flow battery are as follows: firstly, grafting functional groups of different conductive polymers with quinoxaline to prepare a solid anode with a conjugated structure, low negative potential and excellent conductivity, and adopting alkaline electrolyte; dissolving potassium ferrocyanide in alkaline electrolyte to serve as a liquid cathode; the anode and cathode are assembled into a single flow battery.

Preferably, the pH value of the alkaline electrolyte of the constructed all-water mixed flow battery is 7-14.

The invention has the beneficial effects that: the invention takes polypyrrole quinoxaline conducting polymer with low negative potential as a negative electrode, water-soluble potassium ferrocyanide with high positive potential as a liquid flow positive electrode, KOH aqueous solution as electrolyte of the positive electrode and the negative electrode to form a water system mixed energy storage battery, namely a water system single-flow battery. The water system electrolyte is low in cost, safe and environment-friendly, and has wide application prospects in the fields of wind energy, photovoltaic power generation scale electricity storage and power grid peak regulation. When the polypyrrole-quinoxaline conducting polymer is used as a negative electrode, the single electrode potential is low, the voltage of the battery paired with the potassium ferricyanide positive electrode is high, and the coulombic efficiency and the energy efficiency are high.

The invention is further described below with reference to the figures and examples.

Drawings

FIG. 1 is a liquid chromatogram of a pyrrole quinoxaline monomer (a) prepared in comparative example 1, a polypyrrole quinoxaline monomer prepared in example 1(b) and example 4 (c);

FIG. 2 is a cyclic voltammogram of the polypyrroloquinoxalines prepared in examples 1 to 4(a to d);

FIG. 3 is a cyclic voltammogram of the polypyrrole quinoxaline prepared in example 4 at different pH values of the electrolyte;

FIG. 4 is a cyclic voltammogram of a flow battery designed with the polypyrrole quinoxaline prepared in example 4 as the anode and potassium ferricyanide as the cathode;

FIG. 5 is a plot of open circuit voltage versus state of charge (SOC) for a flow battery designed with the polypyrrole quinoxaline prepared in example 6 as the anode and potassium ferricyanide as the cathode;

FIG. 6 is a plot of open circuit voltage versus state of charge (SOC) for a flow battery designed with the polypyrrole quinoxaline prepared in example 7 as the anode and potassium ferricyanide as the cathode.

Detailed Description

The present invention will be described in more detail by way of examples, but the scope of the present invention is not limited to these examples.