An azaxanthone compound, a preparation method thereof and application thereof in a flow battery

Abstract

The application belongs to the field of energy chemical industry, and relates to a nitrogen heteroanthraquinone compound, a preparation method thereof and application of the nitrogen heteroanthraquinone compound in a liquid flow battery. The nitrogen heteroanthraquinone compound has high solubility and high redox potential. The application also relates to application of the nitrogen heteroanthraquinone compound in the liquid flow battery. As a positive active material of an electrolyte of the liquid flow battery, the nitrogen heteroanthraquinone compound can realize high energy density, high voltage efficiency and long cycle life.

Description

Technical Field

[0001] This invention belongs to the field of energy and chemical engineering, specifically relating to an anthraquinone compound, its preparation method, and its application in flow batteries. Background Technology

[0002] Flow batteries, with their advantages of separately adjustable power and energy, fewer geographical limitations, and high safety and reliability, have become a promising large-scale energy storage technology for renewable energy storage. As a key material for energy storage, the cost, energy density, and long-term stability of the electrolyte are crucial for the commercialization of flow batteries.

[0003] To address the issues of high electrolyte cost in vanadium redox flow batteries, cross-contamination between positive and negative electrode electrolytes, and cross-contamination between zinc dendrites and bromine in zinc-bromine flow batteries, aqueous organic flow batteries based on organic active materials have been reported. Aqueous organic flow batteries utilize organic active molecular materials as the active component of the electrolyte. These materials are diverse, inexpensive, and have highly tunable structures. Furthermore, the larger size of organic molecules helps avoid cross-contamination between the positive and negative electrode electrolytes. Among these, anthraquinone molecules have attracted widespread attention due to their stability and low cost. However, currently reported anthraquinone molecules generally suffer from poor water solubility and low potential in acidic solutions. Therefore, there is a need to develop anthraquinone materials with high potential and high solubility in acidic systems. Summary of the Invention

[0004] According to one aspect of this application, a zanthagonal quinone compound is provided, said zanthagonal quinone being an ionic compound having the structure shown in Formula I:

[0005]

[0006] Wherein, the X atom is independently selected from N atoms, or C and N atoms, and the number of N atoms in Formula I is greater than or equal to 1;

[0007] Preferably, the number of nitrogen atoms in the zanthraquinone compound is 2;

[0008] The substituent R on the C atom of the anthraquinone compound 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 It is an H atom;

[0009] The substituent R on the N atom of the anthraquinone compound 1 R 2 R 3 R4 R 5 R 6 R 7 R 8 The alkyl group is independently selected from one or more of the following: C1-C6 alkyl group, C1-C6 hydroxyalkyl group, C1-C6 alkylacetyl group, C1-C6 trimethylaminoalkyl group, C1-C6 triethylaminoalkyl group, C1-C6 sulfonic acid alkyl group, C1-C6 phosphate alkyl group, and C1-C6 carboxylic acid alkyl group.

[0010] Preferably, the substituent R on the N atom of the zanthagonal quinone compound 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 The compounds are methyl, trimethylaminoethyl, ethyl sulfonate, ethyl phosphate, and carboxyethyl.

[0011] Y is a complex anion, independently selected from CH3CO2. - SO4 2- F - Cl - ,Br - I - One or more of them;

[0012] Preferably, the anion Y of the zanthagonal quinone compound is Cl. - .

[0013] m is the number of complex anions, and the sum of the charges of the complex anions is equal to the number of N atoms on the benzene ring.

[0014] The reduced form of the azathraquinone compounds is azathraquinone compounds;

[0015] Reduced anthraquinones are ionic compounds with the structure shown in Formula III:

[0016]

[0017] The reduced nitrogen-anthracene phenolic compounds can be converted into corresponding oxidized nitrogen-anthracene quinone compounds through an oxidation reaction on the electrode, and conversely, the oxidized nitrogen-anthracene quinone compounds can be converted into corresponding reduced nitrogen-anthracene phenolic compounds through a reduction reaction on the electrode.

[0018] The R in the structures of the above-mentioned reduced-state anthraquinones and oxidized-state anthraquinones 1 R 2 R 3 R 4R 5 R 6 R 7 R 8 These are independent substituents, and the choice of these substituents affects the redox potential and charge-discharge cycle stability of the azathraquinone compounds.

[0019] The aforementioned anthraquinone compounds can be used as positive electrode redox active species in the positive electrode electrolyte of flow batteries.

[0020] According to another aspect of this application, a method for preparing the above-mentioned anthraquinone compounds is provided, comprising the following steps:

[0021] The raw materials containing substrate, oxidant and acetonitrile are mixed, reacted, extracted, dried and separated to obtain anthraquinone compounds.

[0022] The substrate is an ionic compound having one or more of the structures shown in Formula II:

[0023]

[0024] Wherein, the X atom is independently selected from N atom, or C and N atom, and the number of N atoms in Formula I is greater than or equal to 1;

[0025] Preferably, the number of nitrogen atoms in the zanthraquinone compound is 2;

[0026] R 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 It is independently selected from one or more of H, C1-C6 alkyl, C1-C6 hydroxyalkyl, C1-C6 alkylacetyl, C1-C6 trimethylaminoalkyl, C1-C6 triethylaminoalkyl, C1-C6 sulfonic acid alkyl, C1-C6 phosphate alkyl, and C1-C6 carboxylic acid alkyl.

[0027] Preferably, the substituent R on the N atom of the zanthagonal quinone compound 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 The compounds are methyl, trimethylaminoethyl, ethyl sulfonate, ethyl phosphate, and carboxyethyl.

[0028] Y is a complex anion, independently selected from CH3CO2.- SO4 2- F - Cl - ,Br - I - One or more of them;

[0029] Preferably, the anion Y of the zanthagonal quinone compound is Cl. - .

[0030] m is the number of complex anions, and the sum of the charges of the complex anions is equal to the number of N atoms on the benzene ring.

[0031] The oxidant includes at least one, or two or more, selected from hydrogen peroxide, tert-butyl hydrogen peroxide, sodium periodate, and potassium persulfate.

[0032] Preferably, the oxidant is hydrogen peroxide.

[0033] The molar ratio of the substrate to the oxidant is 1:1 to 1:10;

[0034] Preferably, the molar ratio of the substrate to the oxidant is 1:5.

[0035] The concentration of the substrate in the acetonitrile is 0.1–0.5 mol / L;

[0036] Preferably, the concentration of the substrate in acetonitrile is 0.2 mol / L.

[0037] The reaction temperature is 15℃-60℃;

[0038] Preferably, the reaction temperature is 25℃-30℃.

[0039] The reaction time is 8h-24h;

[0040] Preferably, the reaction time is 12 hours.

[0041] The extractant is dichloromethane.

[0042] According to another aspect of this application, a positive electrode electrolyte is provided, the positive electrode electrolyte comprising the above-described anthraquinone compounds or anthraquinone compounds prepared by the above-described preparation method.

[0043] According to another aspect of this application, a flow battery is provided, the flow battery comprising the above-described positive electrode electrolyte.

[0044] The coulombic efficiency of the flow battery is above 98%;

[0045] The capacity decay rate of the flow battery is less than 10% after 1000 charge-discharge cycles.

[0046] Generally, to improve the actual energy storage density, the selection of redox active species for the positive and negative electrodes of a flow battery should result in a higher voltage per cell; that is, the potential of the positive electrode redox active species should be as high as possible, and the potential of the negative electrode redox active species should be as low as possible. Additionally, the redox active species for both electrodes should have the highest possible solubility. By adjusting the number and position of nitrogen atoms and the substituents on the nitrogen atoms in the aforementioned anthraquinone molecules, higher redox potentials and solubility can be achieved. Therefore, by selecting these anthraquinone compounds as the positive electrode redox active species for a flow battery and combining them with appropriate negative electrode redox active species, higher single-cell battery voltage and energy storage density can be achieved.

[0047] The flow battery includes a positive electrode electrolyte system A and a negative electrode electrolyte system B;

[0048] The positive electrode electrolyte system A and the negative electrode electrolyte system B of the flow battery are respectively composed of: solvent, redox active species, acid and inorganic salt;

[0049] The redox active species in the positive electrode electrolyte system A of the flow battery are the aforementioned anthraquinone compounds. In actual charge-discharge cycles, the anthraquinone compounds exist in the solution in the form of a [oxidized anthraquinone compound] / [reduced anthraquinone compound] redox couple (a pair of conjugated redox compounds).

[0050] The redox active species in the negative electrode electrolyte system B of the flow battery are selected from Ti2(SO4)3, TiCl3, VSO4, VCl2 or H5[SiW 12 O 40 In actual charge-discharge cycles, the redox active species in electrolyte system B also exist in the form of redox couples, consisting of one or more of the following:

[0051] If the redox active species in electrolyte system B is selected from either Ti2(SO4)3 or TiCl3, the corresponding redox couple is TiO2. 2+ / Ti 3+ ;

[0052] If the redox active species in electrolyte system B are selected from either VSO4 or VCl2, the corresponding redox couple is V 3+ / V 2+ ;

[0053] If the redox active species in electrolyte system B are selected from H4[SiW] 12 O 40 One of them, corresponding to the redox pair H4[SiW] 12 O 40 ] / H5[SiW12 O 40 ].

[0054] The solvent in the positive electrode electrolyte system A and the negative electrode electrolyte system B of the flow battery is water.

[0055] To further increase the solubility of the azathraquinone compounds in the solvent, an acid needs to be added to the solvent system. The acid in the positive electrode electrolyte system A and the negative electrode electrolyte system B of the flow battery is selected from one or more combinations of sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid or trifluoromethanesulfonic acid.

[0056] Preferably, the acid in the positive electrode electrolyte system A and the negative electrode electrolyte system B of the flow battery is selected from sulfuric acid or hydrochloric acid;

[0057] To avoid changes in electrolyte composition due to solute cross-contamination, the positive electrode electrolyte system A and the negative electrode electrolyte system B use the same type of acid.

[0058] To further increase the conductivity of the electrolyte system of the flow battery, inorganic salts need to be added to the solvent system. The inorganic salts in the positive electrode electrolyte system A and the negative electrode electrolyte system B of the flow battery are selected from one or more of sodium sulfate, potassium sulfate, lithium sulfate, ammonium sulfate, sodium chloride, potassium chloride, lithium chloride or ammonium chloride.

[0059] Preferably, the inorganic salts in the positive electrode electrolyte / system A and the negative electrode electrolyte system B of the flow battery are selected from sodium sulfate, potassium sulfate, sodium chloride, or potassium chloride.

[0060] To avoid changes in electrolyte composition due to solute cross-contamination, the types of acid and inorganic salt selected for the positive electrode electrolyte system A and the negative electrode electrolyte system B should preferably be the same. For example, the acid selected for both the positive and negative electrode electrolyte systems of the flow battery is sulfuric acid, and the inorganic salt selected is sodium sulfate.

[0061] Furthermore, to avoid changes in electrolyte composition due to solute cross-contamination, the acid and inorganic salt in the positive and negative electrode electrolyte systems of the flow battery should preferably have the same anion. For example, when sulfuric acid is selected as the acid, the inorganic salt should preferably be selected from sodium sulfate or potassium sulfate; when hydrochloric acid is selected as the acid, the inorganic salt should preferably be selected from sodium chloride or potassium chloride.

[0062] Furthermore, to avoid changes in electrolyte composition due to solute cross-contamination, the redox active species and the acid / inorganic salt selected for the negative electrode electrolyte system B should ideally have the same anion composition. For example, when sulfuric acid is chosen as the acid and sodium sulfate as the inorganic salt, the redox active species selected for the negative electrode electrolyte system B should ideally be selected from either Ti2(SO4)3 or VSO4. Additionally, since H5[SiW12 O 40 As an anionic active species, there is no matching relationship between the active species and the acid / inorganic salt.

[0063] The concentration of anthraquinone compounds in the positive electrode electrolyte system A of the flow battery is 0.01–5.0 mol / L;

[0064] Preferably, the concentration of anthraquinone compounds in the positive electrode electrolyte system A of the flow battery is 1.0-2.0 mol / L;

[0065] The concentration of acid in the positive electrode electrolyte system A of the flow battery is 0.1–5.0 mol / L;

[0066] Preferably, the concentration of acid in the positive electrode electrolyte system A of the flow battery is 1.0-3.0 mol / L;

[0067] The concentration of inorganic salts in the positive electrode electrolyte system A of the flow battery is 0.01–2.0 mol / L;

[0068] Preferably, the concentration of the inorganic salt in the positive electrode electrolyte system A of the flow battery is 0.5-1.0 mol / L.

[0069] The concentration of redox active species in the negative electrode electrolyte system B of the flow battery is 0.01–5.0 mol / L;

[0070] Preferably, the concentration of redox active species in the negative electrode electrolyte system B of the flow battery is 0.5-2.0 mol / L;

[0071] The concentration of acid in the negative electrode electrolyte system B of the flow battery is 0.1–5.0 mol / L;

[0072] Preferably, the concentration of acid in the negative electrode electrolyte system B of the flow battery is 1.0-3.0 mol / L;

[0073] The concentration of inorganic salts in the negative electrode electrolyte system B of the flow battery is 0.01–1.0 mol / L.

[0074] Preferably, the concentration of inorganic salts in the negative electrode electrolyte system B of the flow battery is 0.5-1.0 mol / L.

[0075] To maximize the utilization rate of active species at the positive and negative electrodes in a practical flow battery electrolyte system, the redox active species used in electrolyte systems A and B should have the same electron equivalent (electron equivalent = number of electrons transferred by active species × concentration of active species in electrolyte × electrolyte volume).

[0076] To avoid changes in electrolyte composition due to solute cross-contamination, the concentrations of acid and inorganic salt selected in the positive electrode electrolyte system A and the negative electrode electrolyte system B should preferably be the same. For example, the concentration of acid in both the positive and negative electrode electrolyte systems of the flow battery is 1.0 mol / L, and the concentration of inorganic salt is 1.0 mol / L.

[0077] To facilitate actual charging and discharging operations, the initial state of the assembled flow battery is a fully charged state. At this time, the active species in the positive electrode electrolyte system A are in an oxidized state, and the active species in the negative electrode electrolyte system B are in a reduced state.

[0078] After being discharged, the flow battery enters a state of waiting to be charged. At this time, the active species in the positive electrode electrolyte system A are in a reduced state, and the active species in the negative electrode electrolyte system B are in an oxidized state. After being charged, the flow battery enters a fully charged state, completing one charge-discharge cycle.

[0079] Using the aforementioned anthraquinone compounds as the positive electrode active material in a flow battery electrolyte can achieve high energy density and good charge-discharge cycle stability. These anthraquinone compounds possess high solubility, high redox potential, and good charge-discharge cycle stability. This invention also relates to the application of these anthraquinone compounds in flow batteries, where their use as the positive electrode active material in the electrolyte can achieve high energy density.

[0080] The present invention also relates to the application of the aforementioned anthraquinone compounds in flow batteries, whereby using them as positive electrode active materials for the electrolyte of flow batteries can achieve high energy density, high voltage efficiency and long cycle life.

[0081] Compared with the prior art, the anthraquinone compounds provided by this invention and their application in flow batteries have the following advantages:

[0082] 1) The method for synthesizing the aforementioned anthraquinone compounds is simple, has a high synthesis yield, and low preparation cost;

[0083] 2) The aforementioned anthraquinone compounds have a higher redox potential in acidic systems compared to existing anthraquinone molecules, thus enabling them to achieve higher battery voltages when used as redox active species in flow batteries.

[0084] 3) The aforementioned anthraquinone compounds have higher solubility in acidic systems compared to existing anthraquinone molecules, thus enabling the achievement of higher energy density in flow batteries;

[0085] 4) The aforementioned anthraquinone compounds have good stability and can achieve long-term stable operation in practical flow battery applications. Attached Figure Description

[0086] Figure 1 These are the cyclic voltammetry (CV) test results for the three-electrode system of electrolyte A-2f. The test conditions were: glassy carbon electrode as the working electrode, Pt electrode as the counter electrode, Hg / Hg2SO4 as the reference electrode, and a scan rate of 100 mV / s.

[0087] Figure 2 This is a capacity-voltage curve of a flow battery using electrolyte A-2f as the positive electrode electrolyte and Ti2(SO4)3 as the negative electrode redox active species (corresponding to electrolyte B-1) for the first charge-discharge and 1000th charge-discharge cycles. The test conditions were: charge and discharge current both 60.0 mA·cm⁻¹. -2 The charging cutoff voltage is 1.45V, and the discharging cutoff voltage is 0.7V. Detailed Implementation

[0088] To further illustrate the present invention, the following embodiments are provided based on experimental results and in conjunction with the accompanying drawings, but these embodiments do not limit the scope of the invention as defined by the claims.

[0089] Example 1

[0090] This embodiment illustrates the preparation of the oxidized nitrogen-containing anthraquinone compounds.

[0091] 10 mmol of substrate (synthesized according to the method reported in the literature "Berichte der Deutschen Chemischen Gesellschaft [Abteilung] B: Abhandlungen (1937), 70B, 1760-6", or purchased from Aurora Fine Chemicals Ltd.), 4.5 mL of hydrogen peroxide (30% by mass) and 50 mL of acetonitrile were mixed and reacted for 12 h. The mixture was then extracted with dichloromethane, dried and separated to obtain anthraquinone compounds. The structure of the product was confirmed by NMR.

[0092] The substrates, corresponding products, and yields used in the above preparation methods are shown in the table below:

[0093]

[0094]

[0095] Example 2

[0096] This example illustrates the preparation of other types of oxidized nitrogen-containing anthraquinone compounds.

[0097] 10 mmol of substrate (purchased from Inokai or Aurora Fine Chemicals Ltd.), 4.5 mL of hydrogen peroxide (30% by mass) and 50 mL of acetonitrile were mixed and reacted for 12 h. The mixture was then extracted with dichloromethane, dried and separated to obtain azathraquinone compounds. The structure of the product was confirmed by NMR.

[0098] The substrates, corresponding products, and yields used in the above preparation methods are shown in the table below:

[0099]

[0100] Example 3

[0101] This example illustrates the solubility of the anthraquinone compounds described in Example 1 in 1.0 mol / L sulfuric acid and hydrochloric acid aqueous solutions. The results are as follows:

[0102]

[0103]

[0104] It can be seen that the more hydrophilic functional groups in the said xanthraquinone compounds, the higher their solubility in 1.0 mol / L sulfuric acid and hydrochloric acid aqueous solutions. In general, the said xanthraquinone compounds exhibit high solubility in 1.0 mol / L sulfuric acid and hydrochloric acid solutions.

[0105] Comparative Example 1

[0106] This comparative example illustrates the solubility test of other types of anthraquinone compounds in 1.0 mol / L sulfuric acid and hydrochloric acid aqueous solutions in Example 2. The results are as follows:

[0107]

[0108] It can be seen that the solubility of other types of xanthaquinone compounds in Example 2 in 1.0 mol / L aqueous solutions of sulfuric acid and hydrochloric acid is much lower than that of other types of xanthaquinone compounds described in Comparative Example 1.

[0109] Example 4

[0110] This embodiment illustrates the preparation of different types of anthraquinone compounds as redox active species in the positive electrode electrolyte of Example 1.

[0111] First, prepare a 1.0 mol / L sulfuric acid solution. Then, weigh out 50.0 mmol of sodium sulfate and 50.0 mmol of the aforementioned anthraquinone compound and dissolve them in 50 mL of the sulfuric acid solution. The resulting solution is the positive electrode electrolyte described in this embodiment (wherein the concentration of the anthraquinone compound is 1.0 mol / L and the concentration of sodium sulfate is 1.0 mol / L), denoted as electrolyte Ax. The correspondence between the electrolyte name Ax and the anthraquinone compound is as follows:

[0112]

[0113] Comparative Example 2

[0114] This example illustrates the preparation of other types of anthraquinone compounds as positive electrode electrolytes with redox active species, as described in Example 2.

[0115] First, prepare a 1.0 mol / L sulfuric acid solution. Then, weigh out 50.0 mmol of sodium sulfate and 5.0 mmol of the aforementioned anthraquinone compound and dissolve them in 50 mL of the sulfuric acid solution. The resulting solution is the positive electrode electrolyte described in this embodiment (wherein the concentration of the anthraquinone compound is 0.1 mol / L and the concentration of sodium sulfate is 1.0 mol / L), denoted as electrolyte ax. The correspondence between the electrolyte name ax and the anthraquinone compound is as follows:

[0116]

[0117] Example 5

[0118] This embodiment illustrates the electrochemical performance testing of electrolytes containing compounds described in Example 4 and Comparative Example 2 as redox active species.

[0119] Using a glassy carbon electrode as the working electrode, a Pt electrode as the counter electrode, and Hg / Hg2SO4 as the reference electrode, a scan rate of 100 mV / s was set. Cyclic voltammetry (CV) tests were performed on the electrolytes prepared in Example 4 and Comparative Example 2 using a three-electrode system. The voltage values ​​corresponding to the oxidation and reduction peaks in the CV results were recorded (taking electrolyte A-2b as an example). Figure 1 As shown in the figure, the redox potential ψ of each redox active species in the electrolyte is calculated using the following formula. 0 :

[0120] Redox potential ψ 0 (V) = [Voltage corresponding to oxidation peak (V) + Voltage corresponding to reduction peak (V)] / 2

[0121] The results are shown in the table below:

[0122]

[0123] It can be seen that the redox potential of the aforementioned xanthaquinone compounds is affected by the position and number of nitrogen atoms in the molecule. In general, the xanthaquinone compounds in Example 4 have higher redox potentials than the other types of xanthaquinone compounds in Comparative Example 1.

[0124] Example 6

[0125] This embodiment illustrates the preparation of positive electrode electrolytes with different concentrations of azathraquinone A-2f as the redox active species.

[0126] First, prepare a sulfuric acid aqueous solution with a concentration of 1.0 mol / L. Then, weigh 50.0 mmol of sodium sulfate and a certain amount of azathraquinone A-2f and dissolve them in 50 mL of the above sulfuric acid aqueous solution. The resulting solution is the positive electrode electrolyte described in this embodiment (where the concentration of sodium sulfate is 1.0 mol / L), denoted as A-2f-x.

[0127] The correspondence between the amount and concentration of electrolyte name A-2f-x and azathraquinone A-2f is as follows:

[0128] A-2f-1: The amount added was 25.0 mmol, corresponding to a concentration of 0.5 mol / L;

[0129] A-2f-2: The amount added was 100.0 mmol, corresponding to a concentration of 2.0 mol / L.

[0130] Example 7

[0131] This embodiment illustrates the preparation of positive electrode electrolytes using anthraquinone A-2f as the redox active species and selecting different acid and inorganic salt types.

[0132] First, prepare an aqueous solution with an acid concentration of 1.0 mol / L. Then, weigh 50.0 mmol of inorganic salt and 50.0 mmol of xanthraquinone A-2f into 50 mL of the acid solution. The resulting solution is the positive electrode electrolyte described in this embodiment (where the concentration of xanthraquinone A-2f is 1.0 mol / L and the concentration of inorganic salt is 1.0 mol / L), denoted as electrolyte A-2f-x. The correspondence between the electrolyte name A-2f-x and the types of acid and inorganic salt used is as follows:

[0133] A-2f-3: The acid is sulfuric acid, and the inorganic salt is potassium sulfate;

[0134] A-2f-4: The acid is hydrochloric acid, and the inorganic salt is sodium chloride;

[0135] A-2f-5: The acid is hydrochloric acid, and the inorganic salt is potassium chloride.

[0136] Example 8

[0137] This embodiment illustrates the preparation of positive electrode electrolytes with different acid concentrations, using anthraquinone A-2f as the redox active species.

[0138] First, prepare a sulfuric acid aqueous solution of a certain concentration. Then, weigh out 50.0 mmol of sodium sulfate and 50.0 mmol of xanthraquinone A-2f and dissolve them in 50 mL of the above sulfuric acid solution. The resulting solution is the positive electrode electrolyte described in this embodiment (where the concentration of xanthraquinone A-2f is 1.0 mol / L and the concentration of sodium sulfate is 1.0 mol / L), denoted as electrolyte A-2f-x. The correspondence between the electrolyte name A-2f-x and the sulfuric acid concentration is as follows:

[0139] A-2f-6: concentration 2.0 mol / L;

[0140] A-2f-7: concentration is 3.0 mol / L.

[0141] Example 9

[0142] This embodiment illustrates the preparation of positive electrode electrolytes with different inorganic salt concentrations, using anthraquinone A-2f as the redox active species.

[0143] First, prepare a 1.0 mol / L sulfuric acid aqueous solution. Then, weigh out a certain amount of sodium sulfate and 50.0 mmol of xanthraquinone A-2f and dissolve them in 50 mL of the above sulfuric acid aqueous solution. The resulting solution is the positive electrode electrolyte described in this embodiment (where the concentration of xanthraquinone A-2f is 1.0 mol / L), denoted as electrolyte A-2f-x. The correspondence between the electrolyte name A-2f-x and the amount and concentration of sodium sulfate added is as follows:

[0144] A-2f-8: The amount added was 25.0 mmol, corresponding to a concentration of 0.5 mol / L.

[0145] Example 10

[0146] This embodiment illustrates the preparation of negative electrode electrolytes using different redox active species, acids, and inorganic salt types.

[0147] First, prepare an aqueous solution with an acid concentration of 1.0 mol / L. Then, weigh 100.0 mmol of inorganic salt and a certain amount of negative electrode redox active species and dissolve them in 100 mL of the above acid solution. The resulting solution is the negative electrode electrolyte described in this embodiment (where the inorganic salt concentration is 1.0 mol / L), denoted as Bx. The correspondence between the electrolyte name Bx and the types, amounts, and concentrations of negative electrode redox active species, as well as the types of acid and inorganic salt, is shown in the table below:

[0148]

[0149] Example 11

[0150] This embodiment illustrates the preparation of negative electrode electrolytes with Ti2(SO4)3 as the redox active species and different concentrations of redox active species.

[0151] First, prepare a 1.0 mol / L sulfuric acid aqueous solution. Then, weigh out 100.0 mmol of sodium sulfate and a certain amount of Ti2(SO4)3 and dissolve them in 100.0 mL of the above sulfuric acid aqueous solution. The resulting solution is the negative electrode electrolyte described in this embodiment (where the sodium sulfate concentration is 1.0 mol / L), denoted as Bx. The correspondence between the electrolyte name Bx and the amount and concentration of Ti2(SO4)3 added is as follows:

[0152] B-13: The amount added was 50.0 mmol, corresponding to a concentration of 0.5 mol / L;

[0153] B-14: The amount added was 200.0 mmol, corresponding to a concentration of 2.0 mol / L.

[0154] Example 12

[0155] This embodiment illustrates the preparation of negative electrode electrolytes with different acid concentrations, using Ti2(SO4)3 as the redox active species.

[0156] First, prepare a sulfuric acid aqueous solution of a certain concentration. Then, weigh out 100.0 mmol of sodium sulfate and 100.0 mmol of Ti2(SO4)3 and dissolve them in 100 mL of the above sulfuric acid aqueous solution. The resulting solution is the negative electrode electrolyte described in this embodiment (where the concentration of Ti2(SO4)3 is 1.0 mol / L and the concentration of sodium sulfate is 1.0 mol / L), denoted as electrolyte Bx. The correspondence between the electrolyte name Bx and the sulfuric acid concentration is as follows:

[0157] B-15: Concentration is 0.5 mol / L;

[0158] B-16: Concentration is 2.0 mol / L.

[0159] Example 13

[0160] This embodiment illustrates the preparation of negative electrode electrolytes with different inorganic salt concentrations, using Ti2(SO4)3 as the redox active species.

[0161] First, prepare a 1.0 mol / L sulfuric acid aqueous solution. Then, weigh out a certain amount of sodium sulfate and 100.0 mmol of Ti2(SO4)3 and dissolve them in 100.0 mL of the above sulfuric acid aqueous solution. The resulting solution is the negative electrode electrolyte described in this embodiment (where the Ti2(SO4)3 concentration is 1.0 mol / L), denoted as electrolyte Bx. The correspondence between the electrolyte name Bx and the amount and concentration of sodium sulfate added is as follows:

[0162] B-17: The amount added is 50.0 mmol, corresponding to a concentration of 0.5 mol / L.

[0163] Example 14

[0164] This embodiment illustrates the performance testing of a flow battery using the compounds described in Example 4 and Comparative Example 2 as the positive electrode redox active species, Ti2(SO4)3 as the negative electrode redox active species, sulfuric acid (1.0 mol / L) as the acid, and sodium sulfate (1.0 mol / L) as the inorganic salt.

[0165] A flow battery was assembled using a graphite plate as the current collector, graphite felt as the porous electrodes (positive and negative electrodes), and a polyolefin porous membrane as the separator. Electrolytes prepared in Example 4 and Comparative Example 2 were selected as the positive electrode electrolytes, and electrolyte B-1 from Example 8 was selected as the negative electrode electrolyte. The positive and negative electrolytes were added to the positive and negative electrode storage tanks of the battery, respectively, and then pumped into the positive and negative electrodes of the flow battery. This allowed the electrolytes to return to the positive and negative electrode storage tanks via the battery's liquid outlets, achieving their respective circulation.

[0166] After the positive and negative electrolytes have achieved stable circulation, a charge-discharge apparatus is used, with the charge and discharge current both set to 60.0 mA·cm⁻¹. -2 The charging cutoff voltage is 1.45V, and the discharging cutoff voltage is 0.7V. Charge-discharge performance tests were performed on the above flow batteries, and the capacity-voltage curves were recorded (taking the battery corresponding to positive electrolyte A-2f and negative electrolyte B-1 as an example). Figure 2 As shown), based on the charging and discharging capacities of the 1st and 1000th charge-discharge cycles, the coulombic efficiency (CE) and capacity decay rate are calculated using the following formulas:

[0167] Coulomb efficiency (CE) = [Discharge capacity / Charge capacity] × 100%

[0168] Capacity decay rate = [1 - nth discharge capacity / 1st discharge capacity] × 100%

[0169] The performance of the above-mentioned flow battery during the first and 1000th charge-discharge cycles is shown in the table below:

[0170]

[0171]

[0172] It can be seen that all batteries corresponding to the anthraquinone compounds exhibit good coulombic efficiency (greater than 99.5%) in both the initial and 1000 charge-discharge cycles. Batteries corresponding to electrolytes a-4a, a-4b, and a-4c show significant capacity decay after 1000 charge-discharge cycles (with a maximum capacity decay rate of 21.4%). In summary, selecting appropriate substituents can ensure that the capacity decay rate of the battery after 1000 charge-discharge cycles does not exceed 10% (corresponding to positive electrode electrolytes A-1a to A-3a), and the corresponding anthraquinone compounds exhibit good charge-discharge cycle stability.

[0173] Example 15

[0174] This embodiment illustrates the selection of anthraquinone A-2f as the positive electrode redox active species, and the performance testing of flow batteries with different negative electrode redox active species, acid (1.0 mol / L), and inorganic salt (1.0 mol / L) types.

[0175] The flow battery was installed as described in Example 14. Electrolytes A-2f prepared in Example 4 and A-2f-3 to A-2f-5 prepared in Example 7 were selected as positive electrode electrolytes, and electrolytes B-1 to B-12 prepared in Example 8 were selected as negative electrode electrolytes. After the positive and negative electrode electrolytes achieved stable cycling as described in Example 14, a charge-discharge apparatus was used, with the charge and discharge current set to 60.0 mA·cm⁻¹. -2 The charging cutoff voltage was 1.45V, and the discharging cutoff voltage was 0.7V. The charge and discharge performance of the aforementioned flow battery was tested. The charging and discharging capacities for each charge and discharge cycle were recorded. The performance of the flow battery at the 1st and 1000th charge-discharge cycles, calculated according to the method described in Example 14, is shown in the table below:

[0176]

[0177]

[0178] It can be seen that in the selected negative electrode active species pair (Ti 2+ / Ti 3+ V 3+ / V 2+ H5[SiW 12 O 40 ] / H4[SiW 12 O 40Within the range of electrolyte types (sodium salts, potassium salts), batteries using the aforementioned anthraquinone compound as the positive electrode active species all exhibit good coulombic efficiency and charge-discharge stability, indicating that the aforementioned anthraquinone compound has a certain range of applicability to electrolyte systems.

[0179] Example 16

[0180] This embodiment illustrates the performance testing of a flow battery under different redox active species, acid, and inorganic salt concentrations, using anthraquinone A-2f as the positive electrode redox active species, Ti2(SO4)3 as the negative electrode redox active species, sulfuric acid as the acid, and sodium sulfate as the inorganic salt.

[0181] The flow battery was installed as described in Example 14. Electrolytes A-2f prepared in Example 4, A-2f-1 and A-2f-2 prepared in Example 6, A-2f-6 and A-2f-7 prepared in Example 8, and A-2f-8 prepared in Example 9 were selected as positive electrode electrolytes. Electrolytes B-1 in Example 10, B-13 to B-14 in Example 11, B-15 to B-16 in Example 12, and B-17 in Example 13 were selected as negative electrode electrolytes. After the positive and negative electrode electrolytes achieved stable cycling as described in Example 14, a charge-discharge apparatus was used, with the charge and discharge current set to 60.0 mA·cm⁻¹. -2 The charging cutoff voltage was 1.45V, and the discharging cutoff voltage was 0.7V. The charge and discharge performance of the aforementioned flow battery was tested. The charging and discharging capacities for each charge and discharge cycle were recorded. The performance of the flow battery at the 1st and 1000th charge-discharge cycles, calculated according to the method described in Example 14, is shown in the table below:

[0182]

[0183]

[0184] It can be seen that within the selected concentration ranges of active species (positive electrode active species 1.0-2.0 mol / L), acid (1.0-3.0 mol / L), and inorganic salt (0.5-1.0 mol / L), batteries using the aforementioned anthraquinone compound as the positive electrode active species all exhibit good coulombic efficiency and charge-discharge stability, indicating that the aforementioned anthraquinone compound has a certain range of applicability to electrolyte systems.

[0185] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A triazoanthraquinone compound, characterized in that, The azathraquinone compounds are ionic compounds with the structure shown in Formula I: Equation I; Wherein, the X atom is independently selected from either the N atom or the C atom, and the number of N atoms in Formula I is less than or equal to 2 and greater than or equal to 1; The substituent R on the C atom of the anthraquinone compound 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 It is an H atom; The substituent R on the N atom of the anthraquinone compound 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 The compounds are methyl, trimethylaminoethyl, ethyl sulfonate, ethyl phosphate, and carboxyethyl. Y is a complex anion, independently selected from F. - Cl - ,Br - I - One of them; m is the number of complex anions, and the sum of the charges of the complex anions is equal to the number of N atoms on the ring.

2. A method for preparing the anthraquinone compound according to claim 1, characterized in that, The specific steps are as follows: A mixture of raw materials containing substrate, oxidant and acetonitrile is reacted, extracted, dried and separated to obtain anthraquinone compounds; The substrate is an ionic compound having one or more of the structures shown in Formula II: Formula II; Wherein, the X atom is independently selected from either the N atom or the C atom. Furthermore, the number of N atoms in Formula I is less than or equal to 2 and greater than or equal to 1; The substituent R on the C atom of the anthraquinone compound 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 It is an H atom; The substituent R on the N atom of the anthraquinone compound 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 The compounds are methyl, trimethylaminoethyl, ethyl sulfonate, ethyl phosphate, and carboxyethyl. Y is a complex anion, independently selected from F. - Cl - ,Br - I - One of them; m represents the number of complex anions, and the sum of the charges of the complex anions is equal to the number of N atoms on the benzene ring. The oxidizing agent is hydrogen peroxide.

3. The preparation method according to claim 2, characterized in that, The molar ratio of the substrate to the oxidant is 1:1 to 1:10; The concentration of the substrate in the acetonitrile is 0.1 ~ 0.5 mol / L.

4. The preparation method according to claim 2 or 3, characterized in that, The reaction temperature is 15 ℃ - 60 ℃; The reaction time is 8 h - 24 h; The extractant is dichloromethane.

5. A positive electrode electrolyte, characterized in that, The positive electrode electrolyte contains the azathraquinone compound of claim 1 or the azathraquinone compound prepared by the preparation method of any one of claims 2 to 4.

6. A flow battery, characterized in that, The positive electrode electrolyte used in the flow battery is the positive electrode electrolyte described in claim 5.

7. The flow battery according to claim 6, characterized in that, It uses the aforementioned anthraquinone compounds as redox-active species; The coulombic efficiency of the flow battery is above 98%; The capacity decay rate of the flow battery is less than 10% after 1000 charge-discharge cycles.

8. The flow battery according to claim 6, characterized in that, The flow battery includes a positive electrode electrolyte system A and a negative electrode electrolyte system B; The positive electrode electrolyte system A and the negative electrode electrolyte system B of the flow battery are respectively composed of: solvent, redox active species, acid and inorganic salt; The redox active species in the positive electrode electrolyte system A of the flow battery are the azathanthraquinone compounds. In actual charge-discharge cycles, the azathanthraquinone compounds exist in the solution as a [oxidized azathanthraquinone compound] / [reduced azathanthraquinone compound] redox couple, i.e., a pair of conjugated redox compounds. The redox active species in the negative electrode electrolyte system B of the flow battery are selected from Ti2(SO4)3, TiCl3, VSO4, VCl2 or H5[SiW 12 O 40 One or more combinations of the following; The concentration of anthraquinone compounds in the positive electrode electrolyte system A of the flow battery is 0.01~5.0 mol / L; The concentration of redox active species in the negative electrode electrolyte system B of the flow battery is 0.01~5.0 mol / L.

Images