Aza-anthraquinone compound, preparation method thereof and application of aza-anthraquinone compound in flow battery

Abstract

The invention belongs to the field of energy and chemical industry, and relates to an aza-anthraquinone compound, a preparation method thereof and an application of the aza-anthraquinone compound in a flow battery, and the aza-anthraquinone compound has relatively high solubility and relatively high oxidation-reduction potential. The invention also relates to an application of the aza-anthraquinone compound in a flow battery, and the aza-anthraquinone compound is used as an electrolyte positive electrode active material of the flow battery, so that high energy density, high voltage efficiency and long cycle life can be realized.

Description

Technical Field

[0001] The invention belongs to the field of energy chemical industry, and specifically relates to an aza-anthraquinone compound and a preparation method thereof and application in a liquid flow battery. Background Art

[0002] Liquid flow batteries have become a very promising large-scale energy storage technology in renewable energy storage due to their power and energy being separately controllable, less restricted by geographical scenarios, and safe and reliable. As a key material for energy storage, the cost, energy density, and long-term stability of electrolytes are very important for the commercialization of liquid flow batteries.

[0003] In order to solve the high cost of electrolyte in all-vanadium flow batteries, certain cross-contamination problems between positive and negative electrolytes, and the cross-contamination problem between zinc dendrites and bromine in zinc-bromine flow batteries, aqueous organic flow batteries based on organic active materials have been studied and reported. Aqueous organic flow batteries use organic active molecular materials as active components of electrolytes. They are diverse in type, low in cost, and highly adjustable in structure. In addition, organic molecules can avoid cross-contamination problems between positive and negative electrolytes due to their large size. Among them, anthraquinone molecules have attracted widespread attention due to their stable properties and low cost. However, the anthraquinone molecules reported so far generally have problems such as poor water solubility and low potential in acidic solutions. Therefore, it is necessary to develop anthraquinone materials with high potential and high solubility in acidic systems. Summary of the invention

[0004] According to one aspect of the present application, an azaanthraquinone compound is provided, wherein the azaanthraquinone is an ionic compound having a structure shown in Formula I:

[0005]

[0006] wherein the X atoms are 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 N atoms in the azaanthraquinone compound is 2;

[0008] The substituent R on the C atom of the azaanthraquinone compound 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 is a H atom;

[0009] The substituent R on the N atom of the azaanthraquinone compound 1 , R 2 , R 3 , R4 , R 5 , R 6 , R 7 , R 8 One or more independently selected from C1-C6 alkyl, C1-C6 hydroxyalkyl, C1-C6 alkylacetyl, C1-C6 trimethylaminoalkyl, C1-C6 triethylaminoalkyl, C1-C6 sulfonic acid alkyl, C1-C6 phosphate alkyl, C1-C6 carboxylic acid alkyl;

[0010] Preferably, the substituent R on the N atom in the azaanthraquinone compound is 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 Methyl, trimethylaminoethyl, sulfonic acid ethyl, phosphate ethyl, carboxyethyl;

[0011] Y is a coordinated anion independently selected from CH3CO2 - 、SO4 2- 、F - , Cl - Br - ,I - One or more of the following:

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

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

[0014] The reduced state of the azaanthraquinone compound is an azaanthraphenol compound;

[0015] Reduced azathranol is an ionic compound having the structure shown in Formula III:

[0016]

[0017] The reduced nitrogen anthracene phenol compound can be converted into the corresponding oxidized nitrogen anthracenequinone compound through an oxidation reaction on the electrode, and conversely, the oxidized nitrogen anthracenequinone compound can be converted into the corresponding reduced nitrogen anthracene phenol compound through a reduction reaction on the electrode.

[0018] R in the structures of the above-mentioned reduced azathranols and oxidized azathranolquinone compounds 1 , R 2 , R 3 , R 4, R 5 , R 6 , R 7 , R 8 are mutually independent substituents, and the selection of these substituents affects the redox potential and charge-discharge cycle stability of the azaanthraquinone compound;

[0019] The azaanthraquinone compound can be used as a positive electrode redox active species in a positive electrode electrolyte of a liquid flow battery.

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

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

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

[0023]

[0024] wherein the X atoms are 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;

[0025] Preferably, the number of N atoms in the azaanthraquinone compound is 2;

[0026] R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 One or more independently selected from 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, C1-C6 carboxylic acid alkyl;

[0027] Preferably, the substituent R on the N atom in the azaanthraquinone compound is 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 Methyl, trimethylaminoethyl, sulfonic acid ethyl, phosphate ethyl, carboxyethyl;

[0028] Y is a coordinated anion independently selected from CH3CO2- 、SO4 2- 、F - , Cl - Br - ,I - One or more of the following:

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

[0030] m is the number of coordinated anions, and the total charge carried by the coordinated anions is equal to the number of N atoms on the benzene ring.

[0031] The oxidant includes at least one of hydrogen peroxide, tert-butyl hydroperoxide, sodium periodate and potassium persulfate, or two or more thereof;

[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 to 0.5 mol / L;

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

[0037] The reaction temperature is 15°C-60°C;

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

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

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

[0041] The extractant is dichloromethane.

[0042] According to another aspect of the present application, a positive electrode electrolyte is provided, wherein the positive electrode electrolyte comprises the above-mentioned azaanthraquinone compound or the azaanthraquinone compound prepared by the above-mentioned preparation method.

[0043] According to another aspect of the present application, a liquid flow battery is provided, wherein the liquid flow battery comprises the above-mentioned positive electrode electrolyte.

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

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

[0046] Generally, in order to improve the actual energy storage density, the selection of redox active species at the positive and negative electrodes of the flow battery should make the single cell have a higher voltage, that is, the potential of the positive electrode redox active species is as high as possible, and the potential of the negative electrode redox active species is as low as possible; in addition, the positive and negative electrode redox active species should have the highest possible solubility. By adjusting the number and position of N atoms in the nitrogen anthraquinone molecule and the substituents on the N atoms, it can have a higher redox potential and solubility. Therefore, by selecting the nitrogen anthraquinone compound as the positive electrode redox active species of the flow battery and combining it with appropriate negative electrode redox active species, a higher single cell voltage and energy storage density can be achieved.

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

[0048] The compositions of the positive electrode electrolyte system A and the negative electrode electrolyte system B of the liquid flow battery respectively include: a solvent, redox active species, an acid and an inorganic salt;

[0049] The redox active species in the positive electrode electrolyte system A of the flow battery is the aza-anthraquinone compound. In the actual charge and discharge cycle, the aza-anthraquinone compound exists in the solution in the form of an [oxidized aza-anthraquinone compound] / [reduced aza-anthraquinone compound] pair (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 ] or a combination of two or more thereof, in the actual charge-discharge cycle, the redox active species in the electrolyte system B also exist in the form of an electric pair:

[0051] If the redox active species in the electrolyte system B is selected from one of Ti2(SO4)3 or TiCl3, the corresponding electrode pair is TiO 2+ / Ti 3+ ;

[0052] If the redox active species in the electrolyte system B is selected from one of VSO4 or VCl2, the corresponding electrode pair is V 3+ / V 2+ ;

[0053] If the redox active species in the electrolyte system B is selected from H4[SiW 12 O 40 ], the corresponding pair is 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 liquid flow battery is water.

[0055] In order to further increase the solubility of the aza-anthraquinone compound in the solvent, an acid needs to be added to the solvent system, and the acid in the positive electrode electrolyte system A and the negative electrode electrolyte system B of the liquid flow battery is selected from one or a combination of two or more 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 liquid flow battery is selected from one of sulfuric acid or hydrochloric acid;

[0057] In order to avoid the problem of electrolyte composition change due to solute cross-talk, the type of acid selected for the positive electrode electrolyte system A and the negative electrode electrolyte system B is the same.

[0058] In order to further increase the conductivity of the liquid flow battery electrolyte system, an inorganic salt needs to be added to the solvent system, and the inorganic salt in the positive electrolyte system A and the negative electrolyte system B of the liquid flow battery is selected from one or a combination of two or more of sodium sulfate, potassium sulfate, lithium sulfate, ammonium sulfate, sodium chloride, potassium chloride, lithium chloride or ammonium chloride;

[0059] Preferably, the inorganic salt in the positive electrode electrolyte / system A and the negative electrode electrolyte system B of the flow battery is selected from one of sodium sulfate, potassium sulfate, sodium chloride or potassium chloride;

[0060] In order to avoid the problem of electrolyte composition change caused by solute crosstalk, the types of acid and inorganic salt selected by the positive electrolyte system A and the negative electrolyte system B are preferably the same, for example, the acid selected by the positive and negative electrolyte systems of the liquid flow battery are both sulfuric acid, and the inorganic salt selected is both sodium sulfate;

[0061] Furthermore, in order to avoid the problem of electrolyte composition change caused by solute crosstalk, the acid and inorganic salt in the positive and negative electrolyte systems of the flow battery are preferably consistent in anions. For example, when sulfuric acid is selected as the acid, the inorganic salt is preferably selected from one of sodium sulfate or potassium sulfate; when hydrochloric acid is selected as the acid, the inorganic salt is preferably selected from one of sodium chloride or potassium chloride.

[0062] Furthermore, in order to avoid the problem of electrolyte composition change caused by solute crosstalk, the redox active species selected by the negative electrode electrolyte system B and the acid / inorganic salt are preferably consistent with the anion. For example, when the acid is sulfuric acid and the inorganic salt is sodium sulfate, the redox active species selected by the negative electrode electrolyte system B is preferably selected from one of Ti2(SO4)3 or VSO4. In addition, due to H5[SiW12 O 40 ] is an anionic active species, so there is no matching relationship between the active species and the acid / inorganic salt.

[0063] The concentration of the azoanthraquinone compound in the positive electrode electrolyte system A of the flow battery is 0.01 to 5.0 mol / L;

[0064] Preferably, the concentration of the nitrogen-anthraquinone compound in the positive electrode electrolyte system A of the liquid 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 to 5.0 mol / L;

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

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

[0068] Preferably, the concentration of the inorganic salt in the positive electrode electrolyte system A of the liquid 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 to 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 the acid in the negative electrode electrolyte system B of the flow battery is 0.1 to 5.0 mol / L;

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

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

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

[0075] In order to maximize the utilization rate of positive and negative active species in the actual flow battery electrolyte system, the redox active species used in the electrolyte systems A and B should have the same electron equivalent as much as possible (electron equivalent = number of electrons transferred by active species × concentration of active species in electrolyte × volume of electrolyte).

[0076] In order to avoid the problem of electrolyte composition changes caused by solute cross-talk, the concentrations of the acid and inorganic salt selected for the positive electrolyte system A and the negative electrolyte system B are preferably the same. For example, the acid concentration in the positive and negative electrolyte systems of the liquid flow battery is 1.0 mol / L, and the inorganic salt concentration is 1.0 mol / L.

[0077] In order to facilitate the actual charging and discharging operation, the initial state of the assembled flow battery is a fully charged state, at which time the active species in the positive electrode electrolyte system A is in an oxidized state, and the active species in the negative electrode electrolyte system B is in a reduced state;

[0078] After being discharged, the liquid flow battery enters a state to be charged, at which 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; the liquid flow battery that enters the state to be charged enters a fully charged state after being charged, completing a charge and discharge cycle.

[0079] The nitrogen-anthraquinone compound is used as the positive electrode active material of the electrolyte of the liquid flow battery, and a higher energy density and better charge-discharge cycle stability can be achieved. The nitrogen-anthraquinone compound has a higher solubility, a higher redox potential and better charge-discharge cycle stability. The present invention also relates to the use of the nitrogen-anthraquinone compound in a liquid flow battery, which is used as the positive electrode active material of the electrolyte of the liquid flow battery to achieve a higher energy density.

[0080] The present invention also relates to the application of the azaanthraquinone compound in a liquid flow battery. Using the azaanthraquinone compound as an electrolyte positive electrode active material of the liquid flow battery can achieve high energy density, high voltage efficiency and long cycle life.

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

[0082] 1) The synthesis method of the azaanthraquinone compound is simple, the synthesis yield is high, and the preparation cost is low;

[0083] 2) The aza-anthraquinone compound has a higher redox potential in an acidic system than the existing anthraquinone molecules, so it can achieve a higher battery voltage when used as a positive electrode redox active species of a liquid flow battery;

[0084] 3) The aza-anthraquinone compounds have higher solubility in acidic systems than existing anthraquinone molecules, thus achieving a higher flow battery energy density;

[0085] 4) The aza-anthraquinone compounds have good stability and can achieve long-term stable operation in actual liquid flow battery applications. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0087] Figure 2 The capacity-voltage curves of the flow battery with electrolyte A-2f as the positive electrode electrolyte and Ti2(SO4)3 as the negative electrode redox active species (corresponding to electrolyte B-1) at the first and 1000th charge and discharge. The test conditions are: the charge and discharge current is 60.0mA·cm -2 , the charging cut-off voltage is 1.45V and the discharging cut-off voltage is 0.7V. DETAILED DESCRIPTION

[0088] In order to further illustrate the present invention, the following embodiments are listed according to experimental results in combination with the accompanying drawings, but they do not limit the scope of the invention defined in the claims.

[0089] Example 1

[0090] This example illustrates the preparation of the oxidized nitrogen 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 (mass concentration 30%) and 50 mL of acetonitrile were mixed, reacted for 12 hours, extracted with dichloromethane, dried and separated to obtain azaanthraquinone compounds, and the product structure was confirmed by NMR.

[0092] The substrates used in the above preparation method and the corresponding products and their yields are shown in the following table:

[0093]

[0094]

[0095] Example 2

[0096] This example illustrates the preparation of other types of nitrogen anthraquinone compounds in oxidation states.

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

[0098] The substrates used in the above preparation method and the corresponding products and their yields are shown in the following table:

[0099]

[0100] Example 3

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

[0102]

[0103]

[0104] It can be seen that the more hydrophilic functional groups in the azaanthraquinone compound, the higher its solubility in 1.0 mol / L sulfuric acid and hydrochloric acid aqueous solutions. In general, the azaanthraquinone compound has a higher 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 aza-anthraquinone compounds in Example 2 in 1.0 mol / L sulfuric acid and hydrochloric acid aqueous solutions. The results are as follows:

[0107]

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

[0109] Example 4

[0110] This example illustrates the preparation of a positive electrode electrolyte containing different types of aza-anthraquinone compounds as redox active species in Example 1.

[0111] First, a sulfuric acid solution with a concentration of 1.0 mol / L was prepared, and then 50.0 mmol of sodium sulfate and 50.0 mmol of the aza-anthraquinone compound were weighed and dissolved in 50 mL of the sulfuric acid solution. The obtained solution was the positive electrode electrolyte described in this embodiment (wherein the concentration of the aza-anthraquinone compound was 1.0 mol / L and the concentration of sodium sulfate was 1.0 mol / L), recorded as electrolyte Ax, and the corresponding relationship between the electrolyte name Ax and the aza-anthraquinone compound is as follows:

[0112]

[0113] Comparative Example 2

[0114] This example illustrates the preparation of a positive electrode electrolyte using other types of aza-anthraquinone compounds as redox active species in Example 2.

[0115] First, a sulfuric acid solution with a concentration of 1.0 mol / L is prepared, and then 50.0 mmol of sodium sulfate and 5.0 mmol of the aza-anthraquinone compound are weighed and dissolved 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 aza-anthraquinone compound is 0.1 mol / L and the concentration of sodium sulfate is 1.0 mol / L), which is recorded as electrolyte ax. The corresponding relationship between the electrolyte name ax and the aza-anthraquinone compound is as follows:

[0116]

[0117] Example 5

[0118] This example illustrates the electrochemical performance test of the electrolyte in which the compounds described in Example 4 and Comparative Example 2 are selected as redox active species.

[0119] Using a glassy carbon electrode as a working electrode, a Pt electrode as a counter electrode, and Hg / Hg2SO4 as a reference electrode, the scanning speed was set to 100 mV / s, and a three-electrode system cyclic voltammetry (CV) test was performed on the electrolytes prepared in Example 4 and Comparative Example 2, respectively, and the voltage values ​​corresponding to the oxidation peak and the reduction peak in the CV results were recorded (taking electrolyte A-2b as an example, as shown in FIG. Figure 1 The redox potential of the redox active species in each electrolyte is calculated by 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 following table:

[0122]

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

[0124] Example 6

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

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

[0127] The corresponding relationship between the electrolyte name A-2f-x and the addition amount and concentration of azaanthraquinone A-2f is as follows:

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

[0129] A-2f-2: The added amount is 100.0 mmol, and the corresponding concentration is 2.0 mol / L.

[0130] Example 7

[0131] This example illustrates the preparation of a positive electrode electrolyte using azaanthraquinone A-2f as the redox active species and selecting different acids 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 azaanthraquinone A-2f into 50 mL of the above acid solution, and the resulting solution is the positive electrode electrolyte described in this embodiment (wherein the concentration of azaanthraquinone A-2f is 1.0 mol / L, and the concentration of inorganic salt is 1.0 mol / L), recorded as electrolyte A-2f-x. The corresponding relationship between the electrolyte name A-2f-x and the type 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 example illustrates the preparation of positive electrode electrolytes with different acid concentrations using azaanthraquinone A-2f as the redox active species.

[0138] First, a sulfuric acid aqueous solution of a certain concentration was prepared, and then 50.0 mmol sodium sulfate and 50.0 mmol azaanthraquinone A-2f were weighed and dissolved in 50 mL of the above sulfuric acid solution. The obtained solution was the positive electrode electrolyte described in this embodiment (wherein the concentration of azaanthraquinone A-2f was 1.0 mol / L and the concentration of sodium sulfate was 1.0 mol / L), recorded as electrolyte A-2f-x. The corresponding relationship 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 3.0mol / L.

[0141] Example 9

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

[0143] First, a sulfuric acid aqueous solution with a concentration of 1.0 mol / L was prepared, and then a certain amount of sodium sulfate and 50.0 mmol of azaanthraquinone A-2f were weighed and dissolved in 50 mL of the above sulfuric acid aqueous solution. The obtained solution was the positive electrode electrolyte described in this embodiment (wherein the concentration of azaanthraquinone A-2f was 1.0 mol / L), recorded as electrolyte A-2f-x. The corresponding relationship between the electrolyte name A-2f-x and the amount and concentration of sodium sulfate added is as follows:

[0144] A-2f-8: The added amount is 25.0 mmol, and the corresponding concentration is 0.5 mol / L.

[0145] Example 10

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

[0147] First, an aqueous solution with an acid concentration of 1.0 mol / L is prepared, and then 100.0 mmol of inorganic salt and a certain amount of negative electrode redox active species are weighed and dissolved in 100 mL of the above acid solution. The resulting solution is the negative electrode electrolyte described in this embodiment (wherein the inorganic salt concentration is 1.0 mol / L), which is recorded as Bx. The corresponding relationship between the electrolyte name Bx and the type, dosage and concentration of the negative electrode redox active species, and the type of acid and inorganic salt is as follows:

[0148]

[0149] Embodiment 11

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

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

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

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

[0154] Example 12

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

[0156] First, a sulfuric acid aqueous solution of a certain concentration is prepared, and then 100.0 mmol of sodium sulfate and 100.0 mmol of Ti2(SO4)3 are weighed and dissolved in 100 mL of the sulfuric acid aqueous solution. The obtained solution is the negative electrode electrolyte described in this embodiment (wherein the concentration of Ti2(SO4)3 is 1.0 mol / L and the concentration of sodium sulfate is 1.0 mol / L), which is recorded as electrolyte Bx. The corresponding relationship between the electrolyte name Bx and the sulfuric acid concentration is as follows:

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

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

[0159] Embodiment 13

[0160] This example 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 sulfuric acid aqueous solution with a concentration of 1.0 mol / L, then weigh a certain amount of sodium sulfate and 100.0 mmol of Ti2(SO4)3 and dissolve them in 100.0 mL of the sulfuric acid aqueous solution. The resulting solution is the negative electrode electrolyte described in this embodiment (wherein the concentration of Ti2(SO4)3 is 1.0 mol / L), recorded as electrolyte Bx. The corresponding relationship between the electrolyte name Bx and the amount and concentration of sodium sulfate added is as follows:

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

[0163] Embodiment 14

[0164] This example illustrates the flow battery performance test in which the compounds described in Example 4 and Comparative Example 2 are selected as the positive electrode redox active species, Ti2(SO4)3 is selected as the negative electrode redox active species, sulfuric acid (1.0 mol / L) is selected as the acid, and sodium sulfate (1.0 mol / L) is selected as the inorganic salt.

[0165] A flow battery is assembled with a graphite plate as a current collector, a graphite felt as a porous electrode (positive and negative), and a polyolefin porous membrane as a diaphragm. The electrolytes prepared in Example 4 and Comparative Example 2 are respectively selected as the positive electrolyte, and the electrolyte B-1 in Example 8 is selected as the negative electrolyte. The above-mentioned positive and negative electrolytes are respectively added to the positive and negative electrode storage tanks of the battery, and then introduced into the positive and negative electrodes of the flow battery respectively by a liquid pump, so that the positive and negative electrolytes are returned to the positive and negative electrode storage tanks respectively through the battery liquid path outlet to achieve their respective circulation flows.

[0166] After the positive and negative electrolytes achieve cycle stability, use a charge and discharge instrument and set the charge and discharge current to 60.0 mA cm -2 , charging cut-off voltage 1.45V, discharging cut-off voltage 0.7V, the above flow battery is tested for charging and discharging performance, and the charging and discharging capacity-voltage curve is recorded (taking the battery corresponding to the positive electrode electrolyte A-2f and the negative electrode electrolyte B-1 as an example, Figure 2 According to the charging capacity and discharging capacity of the 1st and 1000th charge and discharge, the coulombic efficiency (CE) and capacity attenuation rate are calculated according to the following formulas:

[0167] Coulombic efficiency (CE) = [discharge capacity / charge capacity] × 100%

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

[0169] The performance of the above flow battery at the first and 1000th charge and discharge cycles is shown in the following table:

[0170]

[0171]

[0172] It can be seen that the batteries corresponding to all aza-anthraquinone compounds can show good coulombic efficiency (greater than 99.5%) in the first and 1000 charge and discharge experiments. The batteries corresponding to electrolytes a-4a, a-4b, and a-4c have obvious capacity decay after 1000 charge and discharge cycles (the capacity decay rate is as high as 21.4%). On the whole, by selecting suitable substituents, the capacity decay rate of the battery after 1000 charge and discharge cycles can be made not more than 10% (corresponding to positive electrode electrolytes A-1a to A-3a), and the active species of the corresponding aza-anthraquinone compounds have good charge and discharge cycle stability.

[0173] Embodiment 15

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

[0175] The flow battery was installed in the manner described in Example 14. The electrolyte A-2f prepared in Example 4 and the electrolytes A-2f-3 to A-2f-5 prepared in Example 7 were selected as the positive electrolytes, and the electrolytes B-1 to B-12 in Example 8 were selected as the negative electrolytes. After the positive and negative electrolytes achieved cycle stability, the charge and discharge instrument was used, and the charge and discharge current was set to 60.0 mA cm -2 , charging cut-off voltage 1.45V, discharging cut-off voltage 0.7V, the above flow battery was tested for charging and discharging performance. The charging capacity and discharging capacity of each charge and discharge were recorded, and the performance of the above flow battery at the first and 1000th charge and discharge cycles was obtained according to the calculation method described in Example 14 as shown in the following table:

[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 40]), acids (sulfuric acid, hydrochloric acid) and inorganic salts (sodium salt, potassium salt), the batteries using the aza-anthraquinone compound as the positive electrode active species all showed good coulombic efficiency and charge and discharge stability, indicating that the aza-anthraquinone compound has a certain scope of application of the electrolyte system.

[0179] Example 16

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

[0181] Install the flow battery in the manner described in Example 14. Select the electrolyte A-2f prepared in Example 4, the electrolyte A-2f-1 and the electrolyte A-2f-2 prepared in Example 6, the electrolyte A-2f-6 and the electrolyte A-2f-7 prepared in Example 8, and the electrolyte A-2f-8 prepared in Example 9 as the positive electrolyte, respectively, and select the electrolyte B-1 in Example 10, the electrolytes B-13 to B-14 in Example 11, the electrolytes B-15 to B-16 in Example 12, and the electrolyte B-17 in Example 13 as the negative electrolyte. Operate in the manner described in Example 14 until the positive and negative electrolytes achieve cyclic stability, use a charge and discharge instrument, and set the charge and discharge current to 60.0 mA cm -2 , charging cut-off voltage 1.45V, discharging cut-off voltage 0.7V, the above flow battery was tested for charging and discharging performance. The charging capacity and discharging capacity of each charge and discharge were recorded, and the performance of the above flow battery at the first and 1000th charge and discharge cycles was obtained according to the calculation method described in Example 14 as shown in the following table:

[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), the batteries using the azaanthraquinone compound as the positive electrode active species exhibit good coulombic efficiency and charge and discharge stability, indicating that the azaanthraquinone compound has a certain range of applicability for the electrolyte system.

[0185] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An aza-anthraquinone compound, characterized in that: The aza-anthraquinone compound is an ionic compound having a structure shown in Formula I: wherein the X atoms are 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; R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 Each of the following 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; Y is a coordinated anion independently selected from CH3CO2 - 、SO4 2- 、F - , Cl - Br - ,I - One or more of the following; m is the number of coordinated anions, and the sum of the charges carried by the coordinated anions is equal to the number of N atoms on the ring.

2. A method for preparing the azaanthraquinone compound according to claim 1, characterized in that: The following steps are involved: The raw materials containing substrate, oxidant and acetonitrile are mixed, reacted, extracted, dried and separated to obtain azaanthraquinone compounds; The substrate is an ionic compound having one or more of the structures shown in Formula II: wherein the X atoms are 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; R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 One or more independently selected from 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, C1-C6 carboxylic acid alkyl; Y is a coordinated anion independently selected from CH3CO2 - 、SO4 2- 、F - , Cl - Br - ,I - One or more of the following; m is the number of coordinated anions, and the sum of the charges carried by the coordinated anions is equal to the number of N atoms on the benzene ring.

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°C-60°C; The reaction time is 8h-24h; The extractant is dichloromethane; The oxidant includes at least one of hydrogen peroxide, tert-butyl hydroperoxide, sodium periodate and potassium persulfate, or two or more thereof.

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

6. A liquid flow battery, characterized in that: The positive electrode electrolyte used in the liquid 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 aza-anthraquinone compound as the redox active species; The coulombic efficiency of the flow battery is above 98%; The capacity attenuation rate of the liquid flow battery after 1000 charge and discharge cycles is less than 10%.

8. The flow battery according to claim 6, characterized in that: The liquid flow battery comprises a positive electrode electrolyte system A and a negative electrode electrolyte system B; The compositions of the positive electrode electrolyte system A and the negative electrode electrolyte system B of the liquid flow battery respectively include: a solvent, redox active species, an acid and an inorganic salt; The redox active species in the positive electrode electrolyte system A of the flow battery is the aza-anthraquinone compound. In the actual charge and discharge cycle, the aza-anthraquinone compound exists in the solution in the form of an [oxidized aza-anthraquinone compound] / [reduced aza-anthraquinone compound] pair (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 ] or a combination of two or more; The concentration of the azoanthraquinone compound in the positive electrode electrolyte system A of the flow battery is 0.01 to 5.0 mol / L; The concentration of redox active species in the negative electrode electrolyte system B of the liquid flow battery is 0.01 to 5.0 mol / L.

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