N-containing heterocyclic aromatic compound aqueous organic flow battery

Abstract

An aqueous organic flow battery containing N-heterocyclic aromatic compounds is disclosed, comprising a single cell or a stack of two or more single cells. Each single cell includes a positive electrode, a separator, and a negative electrode. A positive electrode electrolyte is introduced between the positive electrode and the separator, and a negative electrode electrolyte is introduced between the negative electrode and the separator. The positive electrode electrolyte is an N-containing heterocyclic aromatic compound. The N-containing heterocyclic aromatic compounds disclosed in this invention exhibit excellent redox reversibility and electrochemical stability. When applied to aqueous organic flow batteries, they demonstrate excellent cycle stability, making them a very promising class of positive electrode active molecules.

Description

Technical Field

[0001] This application belongs to the field of flow batteries, specifically relating to an organic flow battery. Background Technology

[0002] With energy structure reform, building a clean, low-carbon, safe, and efficient energy system has become an inevitable trend. The proportion of renewable energy sources such as wind and solar power in the energy structure is gradually increasing. However, these renewable energy sources are characterized by discontinuity, instability, and uncontrollability; large-scale integration into the power grid can affect the stability of the power system. Therefore, advanced large-scale energy storage technologies are needed to effectively store renewable energy generation, thereby smoothing power output, participating in amplitude and frequency regulation, and achieving peak shaving and valley filling. Among these technologies, flow batteries have excellent application prospects in the field of large-scale energy storage due to their advantages such as independently designable output power and energy storage capacity, high safety, long cycle life, and environmentally friendly throughout their entire life cycle.

[0003] Aqueous organic flow batteries primarily utilize water-soluble organic molecules as electrochemical active materials. Organic molecules are widely available and mainly consist of naturally occurring elements such as carbon, hydrogen, oxygen, and nitrogen. Most importantly, the solubility, redox potential, and stability of organic active molecules can be adjusted through molecular engineering modification and electrolyte regulation. In recent years, many organic active molecules have been reported for use in aqueous organic flow batteries, such as quinones, viologens, TEMPO compounds, ferrocene compounds, and heterocyclic aromatic compounds. However, most of the reported organic molecules exhibit poor electrochemical stability and are prone to side reactions that lead to battery capacity decay.

[0004] In summary, it is very important to develop highly stable active organic molecules that can be used in aqueous organic flow batteries. Summary of the Invention

[0005] This invention provides an aqueous organic flow battery containing N-heterocyclic aromatic compounds, which has good cycle stability.

[0006] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0007] This invention provides an organic flow battery, comprising a single cell or a stack of two or more single cells; the single cell includes a positive electrode, a separator, and a negative electrode, wherein a positive electrode electrolyte is introduced into the positive electrode or between the positive electrode and the separator, and a negative electrode electrolyte is introduced into the negative electrode or between the negative electrode and the separator; the positive electrode electrolyte in the positive electrode electrolyte is an N-containing heterocyclic aromatic compound.

[0008] The flow battery described above, wherein the general structural formula of the N-containing heterocyclic aromatic compound is as follows:

[0009]

[0010] In formula (1), X can be independently selected from N and NH; Y can be independently selected from O, S, and O + 、or S + ;

[0011] Dashed lines represent chemical bonds or bonds that do not exist.

[0012] n1 and n2 are selected from: 0, 1, 2, 3, 4;

[0013] m1 and m2 are selected from: 0, 1, 2, 3, 4;

[0014] Each R can be represented independently: -H, -F, -Cl, -Br, -CN, -NH2, -N(CH3)2, -N(CH3)3 + -OH, -SH, -OCH3, -CH3, -SiH3, -CHO, -CF3, -COOH, -COOCH3, -CONH2, -SO3H, -NO2, -PO3H2, -R (alkyl chain);

[0015] Rf represents a functional group: hydroxyl or in:

[0016] Ra and Rb can be the same or different, and can be independently selected from -H, C1-C10 alkyl groups, and -(CH2). n OH, -(CH2) n NH2、-(CH2) n N(CH3)2、-(CH2) n N(CH3)3 + -(CH2) n COOH, -(CH2) n SO3H, -(CH2) n PO3H2, or Ra and Rb together form a substituted or unsubstituted 3-8 membered nitrogen-containing heterocycle or nitrogen-containing heteroaromatic ring, preferably containing N, O or two N, with substituents being C1-C4 alkyl groups, wherein:

[0017] n is a natural number, and its value ranges from 1 to 10.

[0018] The concentration of N-containing heterocyclic aromatic compounds in the positive electrode electrolyte of the aforementioned flow battery is 0.05-5 mol / L.

[0019] In the aforementioned flow battery, the positive or negative electrode is made of carbon felt, carbon cloth, carbon paper, graphite plate, or metal plate, respectively.

[0020] The flow battery, wherein the negative electrode electrolyte contains one or more of the following substances: vanadium dichloride, silicotungstic acid, stannous chloride, cadmium chloride, chromium chloride, lead sulfate, and titanium sulfate.

[0021] The flow battery has a negative electrode electrolyte solution with a total concentration of 0.05 mol / L to its saturation concentration.

[0022] In the flow battery, the separator is an ion exchange membrane or a porous membrane.

[0023] The flow battery further includes a supporting electrolyte in both the positive and negative electrode electrolytes. The supporting electrolyte comprises one or more of hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid, acetic acid, methanesulfonic acid, and trifluoromethanesulfonic acid, and the concentration of the supporting electrolyte is 0.05 mol / L to 6 mol / L; the solvent is water.

[0024] The N-containing heterocyclic aromatic compounds disclosed in this invention have excellent redox reversibility and electrochemical stability. When applied to aqueous organic flow batteries, they exhibit excellent cycle stability and are a very promising class of positive electrode active molecules.

[0025] Beneficial effects of this invention:

[0026] This invention provides an organic flow battery that uses an N-containing heterocyclic aromatic compound as the positive electrode electrolyte. This compound undergoes a reversible redox reaction and exhibits good electrochemical reversibility and stability. Specifically, in an acidic supporting electrolyte, the N-containing heterocyclic aromatic compound possesses a relatively positive redox potential, and the resulting organic flow battery, when matched with a suitable negative electrode electrolyte, demonstrates excellent cycle stability. Furthermore, the N-containing heterocyclic aromatic compound is mainly composed of elements such as carbon, hydrogen, oxygen, nitrogen, and sulfur, and is widely available. Therefore, after large-scale production and manufacturing, the cost of this N-containing heterocyclic aromatic compound organic flow battery is significantly reduced compared to vanadium and other heavy metal ion flow batteries, making it suitable for large-scale energy storage applications. Attached Figure Description

[0027] Figure 1 For compound 1 1 H NMR spectrum;

[0028] Figure 2 The cyclic voltammogram of compound 1 in 3M H2SO4 solution;

[0029] Figure 3 For compound 2 1 H NMR spectrum;

[0030] Figure 4 The cyclic voltammetry diagram of compound 2 in 3M H2SO4 solution;

[0031] Figure 5 For compound 3 1 H NMR spectrum;

[0032] Figure 6 The cyclic voltammetry diagram of compound 3 in 3M H2SO4 solution;

[0033] Figure 7 For compound 4 1 H NMR spectrum;

[0034] Figure 8 The cyclic voltammogram of compound 4 in 3M H2SO4 solution;

[0035] Figure 9 For compound 5 1 H NMR spectrum;

[0036] Figure 10 The cyclic voltammetry diagram of compound 5 in 3M H2SO4 solution;

[0037] Figure 11 For compound 6 1 H NMR spectrum;

[0038] Figure 12 The cyclic voltammetry diagram of compound 6 in 3M H2SO4 solution;

[0039] Figure 13 For compound 7 1 H NMR spectrum;

[0040] Figure 14 The cyclic voltammetry diagram of compound 7 in 3M H2SO4 solution;

[0041] Figure 15 For compound 8 1 H NMR spectrum;

[0042] Figure 16 The cyclic voltammetry diagram of compound 8 in 3M H2SO4 solution;

[0043] Figure 17 For compound 9 1 H NMR spectrum;

[0044] Figure 18 The cyclic voltammetry diagram of compound 9 in 3M H2SO4 solution;

[0045] Figure 19 The cyclic voltammograms of toluidine blue (hereinafter referred to as TB) in 3M H2SO4 solution are shown, with scan rates of 10mV / s, 20mV / s, 50mV / s, 100mV / s, and 200mV / s.

[0046] Figure 20 Cyclic voltammetry of TB at different numbers of cycles in 3M H2SO4 solution;

[0047] Figure 21 The cyclic voltammograms of brilliant cresol blue in 3M H2SO4 solution are shown, with scan rates of 10mV / s, 20mV / s, 50mV / s, 100mV / s, and 200mV / s.

[0048] Figure 22 The graph shows the efficiency and discharge capacity of the battery assembled in Embodiment 12 of the present invention under different current density charging and discharging conditions.

[0049] Figure 23 These are the charge-discharge curves of the battery assembled in Example 12 of the present invention under different current densities;

[0050] Figure 24 The battery assembled in Example 12 of this invention operates at 80 mA / cm. 2 Cyclic performance at current density. Specific implementation methods

[0051] Example 1

[0052] Phenothiazine (1 g, 5 mmol, purchased from Shanghai Aladdin Biochemical Co., Ltd.) was dissolved in 50 mL of glacial acetic acid. A mixed solution of bromine (0.64 mL, 12.6 mmol) and glacial acetic acid (3 mL) was added. After reacting at room temperature for 2.5 hours, 200 mL of an ice-water mixture was added to precipitate the product. The precipitate was filtered and collected. The filter cake was washed successively with water and diethyl ether to obtain the crude product. Further purification was performed by silica gel column chromatography and recrystallization in acetone to obtain green crystals with a yield of 74%. 1 H NMR ( Figure 1 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, confirming the presence of the target product compound 1.

[0053]

[0054] The redox behavior of the electrolyte was studied by cyclic voltammetry. Compound 1 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. Cyclic voltammetry was performed on the prepared electrolyte using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.1–1.2 V.

[0055] like Figure 2 As shown, compound 1 has a pair of redox peaks at 0.9 V vs. SHE, but the reversibility is poor.

[0056] Example 2

[0057] Phenothiazine (1 g, 5 mmol, purchased from Shanghai Aladdin Biochemical Co., Ltd.) was weighed and dissolved in 5 mL of glacial acetic acid. A mixed solution of nitric acid (2.55 mL, 40 mmol) and glacial acetic acid (6 mL) was added dropwise. The reaction was carried out at 35 °C for 48 hours under an inert atmosphere (nitrogen). After cooling to room temperature, 200 mL of an ice-water mixture was added. The mixture was filtered, and the filter cake was collected. The filter cake was washed successively with water and ethanol, and dried under vacuum to obtain a yellow powder with a yield of 68%. 1 H NMR ( Figure 3 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, confirming the presence of the target product compound 2.

[0058]

[0059] The redox behavior of the compound was studied by cyclic voltammetry. Compound 2 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. The prepared electrolyte was subjected to cyclic voltammetry using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.2–1.0 V.

[0060] like Figure 4 As shown, compound 2 has almost no redox peaks in the potential range of 0.2-1.0V.

[0061] Example 3

[0062] 3,7-Dinitrophenthiazide (0.5 g, 1.7 mmol) and SnCl₂·2H₂O (5.66 g, 25.5 mmol) were weighed and dissolved in 30 mL of ethanol. The mixture was refluxed under an inert atmosphere for 5 hours. After cooling to room temperature, ice water was added, and the pH was adjusted to 7 with 5% sodium bicarbonate solution. The mixture was extracted with ethyl acetate (3 × 50 mL). The organic layer was washed with brine and dried over anhydrous sodium sulfate. The mixture was concentrated to a final volume of 5 mL of ethyl acetate, and then 50 mL of petroleum ether was added. The filter cake was collected by filtration and dried under vacuum to obtain a blue powder with a yield of 24%. 1 HNMR ( Figure 5 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, which confirmed the presence of the target product compound 3.

[0063]

[0064] The redox behavior of the compound was studied by cyclic voltammetry. Compound 3 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. The prepared electrolyte was subjected to cyclic voltammetry using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.2–0.8 V.

[0065] like Figure 6 As shown, compound 3 has a pair of reversible redox peaks at 0.58 V vs. SHE, with a redox peak potential difference of ~35 mV, indicating that it underwent a two-electron transfer reaction.

[0066] Example 4

[0067] 3-Hydroxydiphenylamine (1 g, 5.4 mmol, purchased from Anhui Zesheng Technology Co., Ltd.), S (0.345 g, 10.8 mmol), and I2 (0.041 g, 0.162 mmol) were weighed into a flask, and 1,2-dichlorobenzene (7 ml) was added. The mixture was reacted at 180 °C for 4 hours under an inert atmosphere. After cooling to room temperature, the mixture was purified by silica gel column chromatography to obtain a pink powder with a yield of 68%. 1 H NMR ( Figure 7 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, which confirmed the presence of the target product compound 4.

[0068]

[0069] The redox behavior of the compound was studied by cyclic voltammetry. Compound 4 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. The prepared electrolyte was subjected to cyclic voltammetry using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.1–1.0 V.

[0070] like Figure 8 As shown, compound 4 has two pairs of reversible redox peaks, indicating that it can undergo a two-step single-electron redox reaction. The redox potential of the first step is 0.43 V vs. SHE, and the potential of the second step is 0.71 V vs. SHE.

[0071] Example 5

[0072] Weigh 0.5 g (2.42 mmol, purchased from Anhui Zesheng Technology Co., Ltd.), 0.138 g (0.726 mmol), and 1.672 g (12.1 mmol) of K₂CO₃ into a flask, add 0.28 ml (2.66 mmol, purchased from Anhui Zesheng Technology Co., Ltd.) and 5 ml of DMSO, and react at 120 °C for 48 hours under an inert atmosphere. After cooling to room temperature, dilute the reaction mixture with ethyl acetate and wash with water. Extract three times with ethyl acetate. Dry the organic layer with anhydrous sodium sulfate and concentrate to obtain the crude product, which is then purified by silica gel column chromatography to obtain an orange-yellow solid. 1 H NMR ( Figure 9 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, which confirmed the presence of the target product compound 5.

[0073]

[0074] The redox behavior of the compound was studied by cyclic voltammetry. Compound 5 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. The prepared electrolyte was subjected to cyclic voltammetry using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.2–1.0 V.

[0075] like Figure 10 As shown, compound 5 does not have obvious redox peaks in the 0.2-1.0 V range.

[0076] Example 6

[0077] Weigh 0.5 g (1.68 mmol, purchased from Anhui Zesheng Technology Co., Ltd.), 0.096 g (0.5 mmol), and 1.16 g (8.4 mmol) of K₂CO₃ into a flask, add 0.2 ml (1.87 mmol, purchased from Anhui Zesheng Technology Co., Ltd.) and 5 ml of DMSO, and react at 120 °C for 48 hours under an inert atmosphere. After cooling to room temperature, dilute the reaction mixture with ethyl acetate and wash with water. Extract three times with ethyl acetate. Dry the organic layer with anhydrous sodium sulfate and concentrate to obtain the crude product, which is then purified by silica gel column chromatography to obtain a purple solid. 1 H NMR ( Figure 11 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, which confirmed the yield of the target product compound 6.

[0078]

[0079] The redox behavior of compound 6 was studied by cyclic voltammetry. Compound 6 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, followed by a 1 mmol / L solution. The prepared electrolyte was subjected to cyclic voltammetry using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.2–1.0 V.

[0080] like Figure 12 As shown, compound 6 does not have obvious redox peaks in the 0.2-1.0 V range.

[0081] Example 7

[0082] Weigh 0.5 g (2.42 mmol, purchased from Anhui Zesheng Technology Co., Ltd.), 0.138 g (0.726 mmol), and 1.672 g (12.1 mmol) of 3-bromo-4-chloroaniline into a flask, add 0.28 ml (2.66 mmol, purchased from Anhui Zesheng Technology Co., Ltd.) and 5 ml of DMSO, and react at 120 °C for 48 hours under an inert atmosphere. After cooling to room temperature, dilute the reaction mixture with ethyl acetate and wash with water. Extract three times with ethyl acetate. Dry the organic layer with anhydrous sodium sulfate and concentrate to obtain the crude product, which is then purified by silica gel column chromatography to obtain an orange solid. 1 H NMR ( Figure 13 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, which confirmed the presence of the target product compound 7.

[0083]

[0084] The redox behavior of compound 7 was studied by cyclic voltammetry. Compound 7 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. Cyclic voltammetry was performed on the prepared electrolyte using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.2–1.0 V.

[0085] like Figure 14 As shown, compound 7 has two pairs of redox peaks, indicating that two single-electron redox reactions occurred, with redox potentials of 0.4V and 0.6V vs. SHE, respectively.

[0086] Example 8

[0087] Weigh 0.5 g (2.42 mmol, purchased from Anhui Zesheng Technology Co., Ltd.), 0.138 g (0.726 mmol), and 1.672 g (12.1 mmol) of K₂CO₃ into a flask, add 0.28 ml (2.66 mmol, purchased from Anhui Zesheng Technology Co., Ltd.) and 5 ml of DMSO, and react at 120 °C for 48 hours under an inert atmosphere. After cooling to room temperature, dilute the reaction mixture with ethyl acetate and wash with water. Extract three times with ethyl acetate. Dry the organic layer with anhydrous sodium sulfate and concentrate to obtain the crude product, which is then purified by silica gel column chromatography to obtain a purple solid. 1 H NMR ( Figure 15 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, which confirmed the presence of the target product compound 8.

[0088]

[0089] The redox behavior of the electrolyte was studied by cyclic voltammetry. 4-Aminophenothiazine was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. Cyclic voltammetry was performed on the prepared electrolyte using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.2–1.0 V.

[0090] like Figure 16 As shown, compound 8 does not have obvious redox peaks in the 0.2-1.0 V vs. SHE range.

[0091] Example 9

[0092] In air, phenothiazine (2 g, 10 mmol, 1 equiv, purchased from Shanghai Aladdin Biochemical Co., Ltd.) was dissolved in 50 mL of dichloromethane. Iodine (7.64 g, 30 mmol, 3 equiv) and a solution of 200 mL of dichloromethane were slowly added, and the mixture was stirred thoroughly. The reaction was carried out at room temperature for 12 hours. After the reaction was complete, the mixture was filtered under vacuum, the filter cake was washed with dichloromethane, and dried to obtain oxidized phenothiazine.

[0093] 0.724 g (1 mmol) of oxidized phenothiazine was weighed into 30 mL of dichloromethane, and dimethylamine (1 mL, 2 mmol, purchased from Anhui Zesheng Technology Co., Ltd.) was slowly added. The mixture was reacted overnight at room temperature, filtered, and dried under vacuum to obtain a black product with a yield of 25%. 1 H NMR ( Figure 17 The molecular structure was analyzed by liquid chromatography and high-resolution time-of-flight mass spectrometry, which confirmed the yield of the target product compound 9.

[0094]

[0095] The redox behavior of compound 9 was studied by cyclic voltammetry. Compound 9 was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 1 mmol / L solution. Cyclic voltammetry was performed on the prepared electrolyte using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. The scan rate was 50 mV / s, and the scan voltage range was 0.2–1.0 V.

[0096] like Figure 18 As shown, compound 9 has a pair of redox peaks at 0.62 V vs. SHE, indicating a redox reaction involving two electron transfers.

[0097] Example 10

[0098] TB was weighed and dissolved in 10 mL of 3 mol / L sulfuric acid solution. The solution was shaken and stirred until a homogeneous solution was formed, resulting in a 10 mmol / L TB solution. Cyclic voltammetry was performed on the prepared electrolyte using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. Scan rates were 10 mV / s, 20 mV / s, 50 mV / s, 100 mV / s, and 200 mV / s, and the scan voltage range was 0.2–0.8 V.

[0099] Depend on Figure 19 Cyclic voltammetry data show that under acidic conditions, there is a pair of distinct and reversible redox peaks, indicating good electrochemical reversibility. The average redox potential of TB is above 0.5 V vs. SHE.

[0100] Depend on Figure 20 Cyclic voltammetry data at different numbers of cycles show that the cyclic voltammetry curves for the 1st, 500th, and 1000th cycles basically overlap, indicating good stability.

[0101] Example 11

[0102] Brilliant cresol blue was dissolved in 10 mL of 3 mol / L sulfuric acid solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 10 mmol / L solution. Cyclic voltammetry was performed on the prepared electrolyte using a three-electrode system, with silver / silver chloride as the reference electrode, a platinum electrode as the counter electrode, and a glassy carbon electrode as the working electrode. Scan rates were 10 mV / s, 20 mV / s, 50 mV / s, 100 mV / s, and 200 mV / s, and the scan voltage range was 0.2–0.9 V.

[0103] Depend on Figure 21Cyclic voltammetry data show that under acidic conditions, there is a distinct and reversible redox peak, indicating good electrochemical reversibility, with a redox potential above 0.5 V vs. SHE.

[0104] Example 12

[0105] TB was dissolved in 10 mL of 3 mol / L sulfuric acid aqueous solution, and the solution was shaken and stirred until a homogeneous solution was formed, resulting in a 0.3 mol / L TB solution, which was then used as the positive electrode electrolyte. A commercially available vanadium (1.6 MV(III) / V(IV) + 3 M H₂SO₄) electrolyte was used as both the positive and negative electrode electrolytes. The battery was assembled in the following order and position: graphite current collector - carbon felt electrode - ion-conducting membrane PBI - graphite felt electrode - graphite current collector (effective electrode area 48 cm²). 2 A magnetic pump is used to drive the positive and negative electrolytes into the battery cavity. After charging is completed, the negative electrode V(II) is diluted to 0.8 mol / L as the negative electrolyte. The battery is assembled in the following order and position: graphite current collector - carbon felt electrode - ion-conducting membrane PBI - graphite felt electrode - graphite current collector (effective electrode area 9 cm²). 2 A peristaltic pump drives the positive and negative electrolytes into the battery cavity for charging and discharging.

[0106] like Figure 22 As shown, at 20, 40, 60, 80, and 100 mA / cm 2 Under charging and discharging conditions at high current densities, the battery exhibits a coulombic efficiency of approximately 100%, while maintaining high voltage and energy efficiency. Figure 23 As shown, the battery maintains a high capacity at different current densities. Figure 24 As shown, this flow battery operates at 80 mA / cm². 2 Under a current density of 1000 cycles, the efficiency and capacity did not show significant degradation.

Claims

1. An application of an N-containing heterocyclic aromatic compound in an aqueous organic flow battery, comprising a positive electrode electrolyte: characterized in that: The positive electrolyte in the positive electrode electrolyte solution is one or more of N-containing heterocyclic aromatic compounds; The general structural formula of the N-containing heterocyclic aromatic compound is as follows: （1）， In formula (1), X is NH and Y is S; or X is N and Y is S. + ; When Y is S + The anion is Cl. - ; Dashed lines represent chemical bonds or bonds that do not exist. m1 is 0 or 1, m2 is 1; The Rf groups on the two 6-membered rings on the left and right sides are independent functional groups: hydroxyl or... , in: Ra and Rb may be the same or different, and are independently selected from -H, C1-C10 alkyl groups, and -(CH2). n OH, -(CH2) n NH2、-(CH2) n N(CH3)2、-(CH2) n N(CH3)3 + -(CH2) n COOH, -(CH2) n SO3H, -(CH2) n One or more of the nitrogen-containing heterocycles or nitrogen-containing heteroaromatic rings in PO3H2, or Ra and Rb on the same N, together form substituted or unsubstituted 3-8 member nitrogen-containing heterocycles or nitrogen-containing heteroaromatic rings, where n is a natural number and its value ranges from 1 to 10.

2. The application according to claim 1, characterized in that, The structural formula of the N-containing heterocyclic aromatic compound is: 、 、 。 3. The application according to claim 1 or 2, characterized in that, The concentration of N-containing heterocyclic aromatic compounds in the positive electrode electrolyte is 0.05~5 mol / L.

4. The application according to claim 1 or 2, characterized in that, A flow battery includes a single cell or a stack of two or more single cells; a single cell includes a positive electrode, a separator, and a negative electrode arranged in sequence, with the positive electrode electrolyte flowing into the positive electrode and / or the region between the positive electrode and the separator, and the negative electrode electrolyte flowing into the negative electrode and / or the region between the negative electrode and the separator; the positive electrode or negative electrode is one or more of carbon felt, carbon cloth, carbon paper, graphite plate or metal plate.

5. The application according to claim 4, characterized in that, The negative electrode electrolyte in the flow battery contains one or more of the following substances: vanadium dichloride, silicotungstic acid, stannous chloride, cadmium chloride, chromium chloride, lead sulfate, and titanium sulfate.

6. The application according to claim 4, characterized in that, The diaphragm is an ion exchange membrane or a porous membrane.

7. The application according to claim 4, characterized in that, Both the positive and negative electrolytes of the flow battery contain a supporting electrolyte, which includes one or more of hydrochloric acid, sulfuric acid, perchloric acid, phosphoric acid, acetic acid, methanesulfonic acid, and trifluoromethanesulfonic acid; the concentration of the supporting electrolyte is 0.05~6 mol / L; and the solvent is water.

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