Polymeric electrode material, method for preparing the same, and use thereof

Abstract

The application provides a polymeric electrode material and a preparation method and application thereof. The electrode material I has high coulomb efficiency, improves energy conversion efficiency of a flow battery, improves economy and service life of the flow battery; the electrode material I also has good antistatic capacity, solves the problem of static electricity accumulation of the electrode material in a charging and discharging process of the flow battery, and improves performance and safety of the flow battery.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a polymeric electrode material, its preparation method, and its application. Background Technology

[0002] A flow battery is an electrochemical device that stores and converts energy through the flow of an electrolyte between compartments. Flow battery technology is an innovative method of energy storage and conversion, offering enormous potential for various applications, including renewable energy integration, grid stabilization, and electric vehicles. Currently, guided by my country's dual-carbon goals, the concept of green and high-quality development has taken root, leading to the rapid development of the new energy industry and the large-scale construction of energy storage facilities to support it.

[0003] Flow batteries offer a very fast start-up response, and the battery system can operate in a fully enclosed, automated manner. They are easy to maintain, have low operating costs, and offer flexible application options, unrestricted by location or environment. However, their generally lower energy density is a significant drawback. Because the electrolyte in a flow battery is an aqueous solution, all chemical reactions occur within the solution, eliminating any risk of explosion or fire and ensuring high safety. Furthermore, their relatively small electrochemical polarization allows for deep charge-discharge cycles, resulting in a longer battery lifespan.

[0004] Based on the different types of active redox couples in the electrolyte solutions of the positive and negative electrodes, flow batteries can be classified into iron-chromium flow batteries, zinc-bromine flow batteries, all-iron flow batteries, and all-vanadium flow batteries.

[0005] Iron-chromium redox flow battery technology was the earliest prototype of a flow battery. It has advantages such as high safety with no risk of explosion and long service life. However, the negative electrode reaction kinetics of the battery is slow and the hydrogen evolution reaction is serious. At the same time, the iron-chromium redox flow battery stack is prone to thermal expansion and contraction in high and low temperature environments, which can easily lead to leakage problems and cause environmental pollution.

[0006] The biggest advantage of vanadium redox flow batteries is that the redox couple uses the same element, vanadium, for both the positive and negative electrodes. The electrolyte is regenerable during long-term operation, avoiding the problem of difficult capacity recovery due to cross-contamination. Furthermore, the battery exhibits excellent reliability with no significant hydrogen or oxygen evolution side reactions during operation, and has now entered the stage of large-scale commercial demonstration operation and market development. However, its technical cost is relatively high, and vanadium easily generates highly toxic vanadium pentoxide, which is not environmentally friendly. Therefore, there is an urgent need to find a greener, more environmentally friendly, and cheaper electrode material. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, this invention provides a polymeric flow battery electrode material, its preparation method, and its application.

[0008] This invention provides an electrode material I for a polymeric flow battery, which comprises the following structure:

[0009]

[0010] in,

[0011] R1 and R2 are independently selected from C1-C 12 Alkyl groups;

[0012] Specifically, R1 and R2 can be independently selected from: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, n-pentyl, isopentyl, cyclohexyl, n-heptyl, n-octyl, isooctyl, n-nonyl, isonyl, n-decyl, isodel, undecyl, or dodecyl, etc.

[0013] X1 is selected from halogens;

[0014] Specifically, X1 can be selected from Br, Cl or I.

[0015] n is an integer from 1 to 11, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11.

[0016] m is an integer from 1 to 11, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11.

[0017] p is an integer from 1 to 20, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, etc.

[0018] A second aspect of the present invention provides a method for preparing electrode material I for a flow battery, the preparation process of which is as follows:

[0019]

[0020] The preparation method specifically includes the following steps:

[0021] (i) Structure A and structure B react in a solvent to generate intermediate I-1;

[0022] (ii) Intermediate I-1 is converted into intermediate I-2 under the action of peroxide and catalyst;

[0023] (iii) Intermediate I-2 and structure C react in a polar solvent to generate electrode material I.

[0024] in,

[0025] X1 in structure B is selected from halogens, such as Br, Cl or I.

[0026] In structure B, X2 is selected from Br, Cl, I, or -OH, etc.

[0027] Preferably, the solvent used in step (i) is selected from any one of ethyl acetate, acetonitrile, toluene, xylene, cyclohexane, heptane, octane, or dichloromethane.

[0028] Specifically, the reaction in step (i) also requires the addition of an acid-binding agent.

[0029] Preferably, the acid-binding agent is one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, or potassium hydroxide.

[0030] Specifically, the molar ratio of structure A to structure B is 1:1.5-4.5, for example 1:(1.5, 1.8, 2.0, 2.05, 2.2, 2.4, 2.5, 2.6, 2.8, 3.0, 3.5, 4.0 or 4.5, etc.), preferably 1:1.9-3.5.

[0031] Specifically, the reaction temperature of step (i) is -20℃ to 60℃, for example -20℃, -15℃, -10℃, -9℃, -8℃, -7℃, -6℃, -5℃, -4℃, -3℃, -2℃, -1℃, 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃, 10℃, 15℃, 20℃, 30℃, 40℃, 50℃ or 60℃, preferably -10℃ to 40℃, more preferably -10℃ to 20℃.

[0032] Specifically, the reaction time of step (i) is 6-24h, such as 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 18h, 20h, 22h or 24h, preferably 6-18h.

[0033] Specifically, the reaction in step (i) needs to be carried out under the protection of an inert gas.

[0034] Preferably, the inert gas is selected from nitrogen or argon.

[0035] Preferably, the peroxide is either tert-butyl hydrogen peroxide or hydrogen peroxide.

[0036] Preferably, the catalyst is any one of magnesium sulfate, magnesium hydroxide, sodium tungstate, or copper bromide.

[0037] Specifically, the molar ratio of intermediate I-1 to peroxide is 1:3-8, for example 1:(3.0, 3.2, 3.5, 3.8, 4.0, 4.2, 4.5, 4.6, 4.8, 5.0, 5.2, 5.4, 5.5, 5.6, 5.8, 6.0, 6.5, 7.0, 7.5 or 8.0, etc.).

[0038] Specifically, the molar ratio of intermediate I-1 to the catalyst is 1:0.001-0.15, for example, 1:(0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.055, 0.06, 0.065, 0.07, 0.75, 0.08, 0.085, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15, etc.).

[0039] Specifically, the reaction in step (ii) also requires the addition of a solvent, which is selected from any one of water, xylene, cyclohexane, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, methanol, and ethanol.

[0040] Specifically, the reaction temperature in step (ii) is 30-150°C, such as 30°C, 40°C, 50°C, 60°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C, preferably 30-120°C, and more preferably 40-100°C.

[0041] Specifically, the reaction time of step (ii) is 8-72 hours, such as 8 hours, 12 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, 40 hours, 44 hours, 48 ​​hours, 52 hours, 56 hours, 60 hours, 64 hours, 68 hours, or 72 hours, preferably 8-36 hours.

[0042] Preferably, the polar solvent is selected from any one of water, xylene, cyclohexane, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, methanol, and ethanol.

[0043] Specifically, step (iii) also requires the addition of a catalyst.

[0044] Preferably, the catalyst is selected from either potassium iodide or sodium iodide.

[0045] Specifically, the reaction temperature of step (iii) is 30-150℃, such as 30℃, 40℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 110℃, 115℃, 120℃, 130℃, 140℃ or 150℃, preferably 40-100℃.

[0046] Specifically, the reaction time of step (iii) is 6-36 hours, such as 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 34 hours or 36 hours, preferably 8-24 hours.

[0047] A third aspect of the present invention provides an electrode material I for a flow battery, which is prepared by the method described above.

[0048] In a fourth aspect of the invention, the application of the electrode material I or the electrode material I obtained by the preparation method described herein is provided in a flow battery.

[0049] In a fifth aspect of the invention, a flow battery system is provided, comprising a positive electrode reservoir, a negative electrode reservoir, and a flow battery stack, wherein the two ends of the flow battery stack are respectively connected to the positive electrode reservoir and the negative electrode reservoir, and the positive electrode reservoir and the negative electrode reservoir are reservoirs storing electrolyte.

[0050] Specifically, the flow battery stack includes a battery separator that divides the flow battery into a positive electrode region and a negative electrode region. A positive current collector is installed in the positive electrode region, and a negative current collector is installed in the negative electrode region. The positive electrode region is connected to a positive electrode storage tank via a positive electrode circulation pipeline, and the negative electrode region is connected to a negative electrode storage tank via a negative electrode circulation pipeline. The positive electrode electrolyte in the positive electrode storage tank contains electrode material I of the polymeric flow battery and a supporting electrolyte. The negative electrode electrolyte in the negative electrode storage tank is an electrolyte containing a methyl viologen derivative and a supporting electrolyte. The battery separator supports electrolyte penetration while preventing the penetration of positive and negative electrode active materials.

[0051] Specifically, the flow battery also includes a pump system for delivering the electrolyte.

[0052] Preferably, the pump set can be any one of a peristaltic pump, a mechanical pump, or a magnetic pump.

[0053] Preferably, the membrane can be any one of a cation exchange membrane, anion exchange membrane, and selectively permeable membrane.

[0054] Preferably, the electrolyte is an aqueous solution of NaCl or an aqueous solution of KCl.

[0055] The beneficial effects of this invention are:

[0056] 1. The electrode material I of the present invention, as a positive electrode material, reduces the loss of active material and energy, improves the energy conversion efficiency of the flow battery, and improves the economy and service life of the flow battery.

[0057] 2. The electrode material I of the present invention, as an antistatic agent, has good antistatic ability, promotes ion transport and electrochemical reaction in the flow battery, and improves the battery efficiency and safety performance.

[0058] 3. The electrode material I of this invention is produced by reacting a piperidine ring analog with an acyl halide, followed by oxidation to obtain a nitroxide radical derivative, which is then reacted with a nitrogen-containing organic compound to generate a nitroxide radical derivative containing a quaternary ammonium salt and an amide. The synthesis process is simple, efficient, and inexpensive. Detailed Implementation

[0059] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Raw materials 1-1, 2-1, 3-1 and 4-1 were prepared according to the synthesis method described in Example 1 of patent application CN104211636A.

[0061] Example 1

[0062]

[0063] Under nitrogen protection, 1 mol of raw material 1-1 was dissolved in 500 ml of cyclohexane in a four-necked flask. The reaction temperature was controlled between -5℃ and 0℃. 2 mol of raw material 1-2 and 1.1 mol of sodium carbonate aqueous solution (30% mass fraction) were slowly added and reacted for 12 h. The mixture was washed, filtered, and dried to obtain intermediate product I-1-1.

[0064] Disperse intermediate product I-1-1 in 500 ml of water, add 0.05 mol of sodium tungstate, slowly add 4 mol of tert-butyl hydrogen peroxide, control the reaction temperature at 80 °C, react for 24 h, filter, and concentrate to obtain intermediate product I-1-2.

[0065] Intermediate product I-1-2 was placed in a four-necked flask, 400 ml of ethanol was added, and 1.05 mol of starting material 1-3 was added. The mixture was reacted at 60 °C for 12 h, and then concentrated to obtain the target product I-1 with a yield of 78.3%, molecular weight (Mn): 6547, and viscosity (100 °C): 26 cps.

[0066] Example 2

[0067]

[0068] Under nitrogen protection, 1 mol of raw material 2-1 was dissolved in 600 ml of dichloromethane in a four-necked flask. The reaction temperature was controlled between 0℃ and 5℃. 2.05 mol of raw material 2-2 and 2.1 mol of sodium hydroxide aqueous solution (40% mass fraction) were slowly added and reacted for 14 h. The mixture was filtered, washed, and dried to obtain intermediate product II-2-1.

[0069] Disperse intermediate product II-2-1 in 650 ml of water, add 0.05 mol of sodium tungstate, slowly add 4.5 mol of hydrogen peroxide, control the reaction temperature at 70℃, react for 18 h, filter, and concentrate to obtain intermediate product II-2-2.

[0070] Intermediate product II-2-2 was placed in a four-necked flask, 500 ml of methanol was added, and 1 mol of raw material 2-3 was added. The mixture was reacted at 60 °C for 18 h, and then concentrated to obtain the target product II-1. Yield: 81.6%, molecular weight (Mn): 7812, viscosity (100 °C): 49 cps.

[0071] Example 3

[0072]

[0073] Under nitrogen protection, 1 mol of raw material 3-1 was dissolved in 600 ml of acetonitrile in a four-necked flask. The reaction temperature was controlled between -2℃ and 3℃. 2.05 mol of raw material 3-2 and 1.2 mol of potassium carbonate aqueous solution (30% mass fraction) were slowly added and reacted for 14 h. The mixture was filtered, washed, and dried to obtain intermediate product Ⅲ-3-1.

[0074] Intermediate product III-3-1 was dispersed in 650 ml of cyclohexane, 0.05 mol of sodium tungstate was added, and 4.5 mol of hydrogen peroxide was slowly added dropwise. The reaction temperature was controlled at 70 °C and the reaction was carried out for 18 h. After filtration and concentration, intermediate product III-3-2 was obtained.

[0075] The intermediate product Ⅲ-3-2 was placed in a four-necked flask, 400 ml of methanol was added, and 1.1 mol of the starting material 3-3 was added. The mixture was reacted at 60 °C for 15 h, and then concentrated to obtain the target product Ⅲ-1 with a yield of 83.6%, a molecular weight (Mn) of 8759, and a viscosity (100 °C) of 57 cps.

[0076] Example 4

[0077]

[0078] Under nitrogen protection, 1 mol of raw material 4-1 was dissolved in 600 ml of acetonitrile in a four-necked flask. The reaction temperature was controlled between -5℃ and 0℃. 2 mol of raw material 4-2 and 2.1 mol of potassium hydroxide aqueous solution (30% by mass) were slowly added and reacted for 12 h. The mixture was then filtered, washed, and dried to obtain intermediate product Ⅳ-4-1.

[0079] Disperse intermediate IV-4-1 in 650 ml of water, add 0.06 mol of copper bromide, slowly add 6 mol of hydrogen peroxide, control the reaction temperature at 70 °C, react for 18 h, filter, and concentrate to obtain intermediate IV-4-2.

[0080] The intermediate product IV-4-2 was placed in a four-necked flask, 400 ml of ethanol was added, 10% mol of potassium iodide was added, and 0.98 mol of starting material 4-3 was added. The mixture was reacted at 70 °C for 18 h, and then concentrated to obtain the target product IV-1. The yield was 79.4%, the molecular weight (Mn) was 10238, and the viscosity (100 °C) was 16 cps.

[0081] Comparative Example 1

[0082] The structure of compound A-1 is shown below:

[0083] The compound A-1 was prepared according to the synthesis method described in PCT patent application WO2022 / 251610A1.

[0084] Comparative Example 2

[0085] The structure of compound A-2 is shown below:

[0086] The compound A-2 was prepared according to the synthesis method described in PCT patent application WO2022 / 251610A1.

[0087] Example 5: Electrochemical Performance Testing

[0088] This experiment tests the electrochemical performance of a single-cell battery. The measured geometric area of ​​the battery is 2*2 cm². The battery separator is a HoAM G-1204 anion exchange membrane, which was directly immersed in a 1 mol / L NaCl aqueous solution for 1 hour before use. The battery testing mold was provided by Wuhan Chuxin Technology Co., Ltd. The positive electrode electrolyte is 0.1 mol / L positive electrode active material + 1 mol / L NaCl aqueous solution; the negative electrode electrolyte is methyl viologen + 1 mol / L NaCl aqueous solution.

[0089] The assembled flow batteries were subjected to cycle stability tests at room temperature (25℃). The testing equipment was a Shenzhen Xinwei Battery Tester, with the test voltage set to 0.1-1.7V and the flow rate to 25ml / min.

[0090] The positive electrode active material is of type 1#, 2#, 3#, 4#, 5#, 6#, or 7#. Specifically,

[0091] #1 represents the nitroxide radical of 2,2,6,6-tetramethylpiperidinol (control);

[0092] #2 is electrode material I-1 of the flow battery (prepared in Example 1);

[0093] #3 is electrode material I of the flow battery, II-1 (prepared in Example 2);

[0094] 4# is electrode material I of flow battery, Ⅲ-1 (prepared in Example 3);

[0095] 5# is electrode material I of the flow battery, Ⅳ-1 (prepared in Example 4);

[0096] 6# is compound A-1 (prepared in Comparative Example 1);

[0097] 7# is compound A-2 (prepared in Comparative Example 2);

[0098] Its electrochemical properties are as follows:

[0099] Table 1: Comparison of Electrochemical Performance

[0100]

[0101] As shown in Table 1, the coulombic efficiency of the prepared electrode material I is higher than that of the nitroxide radical of 2,2,6,6-tetramethylpiperidinol, and the coulombic efficiency is above 98%. This indicates that the electrode material I of the present invention has less active material loss and energy loss during the charging and discharging process of the flow battery, thereby improving the energy conversion efficiency of the flow battery and improving the economy and service life of the flow battery.

[0102] Example 6: Performance test as an antistatic agent

[0103] Standard formula:

[0104] Prepare the standard PP formulation according to the proportions in Table 2, and then add antistatic agents to obtain 1# to 5# respectively.

[0105] Table 2 Standard Formulation

[0106] Components Ratio (by weight) PP 100 Antioxidant 1010 0.1 Antioxidant 168 0.2

[0107] #1 contains 1.5 wt% Clariant SAS93 antistatic agent (control) of the total weight of the standard formulation;

[0108] 2# Electrode material I-1 for flow batteries after drying, containing 2 wt% of the total weight of the standard formulation (prepared in Example 1);

[0109] Electrode material II-1 for flow batteries, containing 2 wt% of the total weight of the standard formulation after drying (prepared in Example 2);

[0110] Electrode material Ⅲ-1 for flow batteries after drying, containing 2wt% of the total weight of the standard formulation (prepared in Example 3);

[0111] 5# Electrode material Ⅳ-1 for flow batteries after drying, containing 2wt% of the total weight of the standard formulation (prepared in Example 4);

[0112] The above materials are mixed and then melt-extruded, granulated and injection molded to obtain standard test strips.

[0113] The antistatic properties of the fiber-reinforced plastics were tested according to GB / T 15738-2008, Test Method for Resistivity of Conductive and Antistatic Fiber-Reinforced Plastics. Specific results are shown in Table 3.

[0114] Table 3 Comparison of Antistatic Properties

[0115] serial number Surface resistivity (Ω) 1# <![CDATA[1.31*10 9 ]]> 2# <![CDATA[1.23*10 9 ]]> 3# <![CDATA[1.06*10 9 ]]> 4# <![CDATA[1.04*10 9 ]]> 5# <![CDATA[1.15*10 9 ]]>

[0116] According to the results in Table 3, the surface resistivity of the electrode materials prepared through the examples is lower than that of the Klein antistatic agent, indicating that electrode material I of the present invention has good antistatic ability. Antistatic agents are often added to flow batteries to eliminate static electricity, promote ion transport and electrochemical reactions, and improve battery efficiency and performance. Furthermore, the accumulation of static electricity can damage electrode materials, affecting the long-term stability and safety of the battery.

[0117] Therefore, the electrode material I of the present invention can not only be used as the positive electrode material of the flow battery, but also as an antistatic agent, which improves the energy conversion efficiency of the flow battery. It also solves the problem of static electricity accumulation in the electrode material during the charging and discharging process of the flow battery, thereby improving the performance and safety of the flow battery.

[0118] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0119] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. An electrode material I for a polymeric flow battery, characterized in that, It contains the following structure: in, R1 and R2 are independently selected from C1-C 12 Alkyl groups; X1 is selected from halogens; n is an integer from 1 to 11; m is an integer from 1 to 11; p is an integer from 1 to 20.

2. The electrode material I according to claim 1, characterized in that, R1 and R2 are independently selected from any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, n-pentyl, isopentyl, cyclohexyl, n-heptyl, n-octyl, isooctyl, n-nonyl, isonyl, n-decyl, isodecyl, undecyl, or dodecyl. Preferably, X1 is selected from Br, Cl or I.

3. A method for preparing electrode material I according to claim 1 or 2, characterized in that, The preparation process is as follows: Among them, X2 is selected from Br, Cl, I, and -OH; Specifically, the preparation method includes the following steps: (i) Structure A and structure B react in a solvent to generate intermediate I-1; (ii) Intermediate I-1 is converted into intermediate I-2 under the action of peroxide and catalyst; (iii) Intermediate I-2 and structure C react in a polar solvent to generate electrode material I.

4. The preparation method according to claim 3, characterized in that, The solvent mentioned in step (i) is selected from any one of ethyl acetate, acetonitrile, toluene, xylene, cyclohexane, heptane, octane, or dichloromethane; Preferably, the reaction in step (i) needs to be carried out under the protection of an inert gas, wherein the inert gas is selected from nitrogen or argon.

5. The preparation method according to claim 3, characterized in that, The reaction temperature in step (i) is -20℃ to 60℃, more preferably -10℃ to 40℃, and even more preferably -10℃ to 20℃; Preferably, the reaction time for step (i) is 6-24 hours, and more preferably 6-18 hours.

6. The preparation method according to claim 3, characterized in that, The peroxide mentioned in step (ii) is either tert-butyl hydrogen peroxide or hydrogen peroxide solution; Preferably, the catalyst in step (ii) is any one of magnesium sulfate, magnesium hydroxide, sodium tungstate, or copper bromide.

7. The preparation method according to claim 3, characterized in that, The molar ratio of intermediate I-1 to peroxide is 1:3-8; Preferably, the molar ratio of intermediate I-1 to catalyst is 1:0.001-0.

15.

8. The preparation method according to claim 3, characterized in that, The reaction temperature in step (ii) is 30-150°C, more preferably 30-120°C, and even more preferably 40-100°C; Preferably, the reaction time for step (ii) is 8-72 hours, and more preferably 8-36 hours.

9. The preparation method according to claim 3, characterized in that, The polar solvent in step (iii) is selected from any one of water, xylene, cyclohexane, N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, methanol, and ethanol. Preferably, the reaction temperature in step (iii) is 30-150°C, more preferably 40-100°C; Preferably, the reaction time of step (iii) is 6-36 hours, and more preferably 8-24 hours.

10. A flow battery comprising a positive electrode electrolyte and a negative electrode electrolyte, wherein the positive electrode electrolyte comprises electrode material I as described in claim 1 or 2 or electrode material I obtained by the preparation method according to any one of claims 3-9.

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