A molecularly driven method for preparing high-performance sulfur-based flow batteries

Abstract

The present invention provides a method for preparing a molecular-driven high-performance sulfur-based liquid flow battery, wherein the liquid flow battery comprises positive and negative electrolytes, positive and negative electrodes, a diaphragm, a liquid storage tank, a filter, a light shield, and a circulation pump; the negative electrolyte comprises a negative active substance, a negative supporting electrolyte, and redox mediator molecules, and the positive electrolyte comprises a positive active substance and a positive supporting electrolyte; the liquid flow battery of the present invention accelerates the kinetic reaction of sulfides and slows down the shuttle effect of sulfides, and has the advantages of low cost, high energy density, high energy efficiency, high stability, long cycle life, and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage, and in particular relates to a method for preparing a molecule-driven high-performance sulfur-based liquid flow battery. Background Art

[0002] The development and application of electrochemical energy storage technology is one of the key strategies to solve the challenges of the current energy crisis. Particularly noteworthy is the redox flow battery system, which has shown significant competitive advantages in the arena of large-scale energy storage technology with its excellent safety properties, ultra-long cycle durability, and flexible decoupling design of power and energy storage. In this context, sulfide has become the preferred material for building advanced sulfur-based flow battery systems due to its economic advantages and high solubility characteristics.

[0003] However, the inherent kinetic sluggishness of the sulfide system seriously inhibits the energy conversion efficiency and achievable working current density of sulfur-based flow batteries, which constitutes a major bottleneck in the advancement of technology. The prior art [US 2023 / 0307682 A1] uses molecular catalysts to catalyze sulfur-based flow batteries using S4 with low solubility. 2- / S2 2- As the active material, the redox couple reduces the energy density of sulfur-based flow batteries due to the low solubility of high-valent sulfides. The negative electrode electrolyte is an alkaline environment, which requires higher corrosion resistance of battery materials and poor safety. In addition, the irreversible decomposition reaction of molecular catalysts under alkaline conditions also reduces the cycle stability of sulfur-based flow batteries.

[0004] In addition, the shuttle effect of sulfides in existing sulfur-based flow battery systems during battery cycling exacerbates the capacity decay of sulfur-based flow batteries, directly restricting the cycle life of sulfur-based battery systems, thereby affecting their reliability and ability to maintain performance under long-term operating conditions. Therefore, how to overcome the kinetic limitations of sulfides in the shuttle effect has become a core scientific and technological challenge in improving the performance and practical value of sulfur-based flow batteries. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a high-performance molecule-driven sulfur-based flow battery, which accelerates the kinetic reaction of sulfides, slows down the shuttle effect of sulfides, improves the energy density, energy efficiency, stability, and cycle life of sulfur-based flow batteries, and reduces production costs;

[0006] The second purpose of the embodiment of the present invention is to provide a method for preparing a molecularly driven high-performance sulfur-based liquid flow battery.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is a method for preparing a molecularly driven high-performance sulfur-based liquid flow battery, comprising the following steps:

[0008] S1. preparing a diaphragm: immersing an ion exchange membrane in an alkaline solution for ionization treatment;

[0009] S2, rinse the deionized ion exchange membrane with deionized water until it becomes neutral, and soak it in deionized water for later use;

[0010] S3, preparing a negative electrode electrolyte: using deionized water and sulfide to prepare a sulfide solution A, using a supporting electrolyte and deionized water to prepare a negative electrode supporting electrolyte solution B, adding a redox mediator molecule to the negative electrode supporting electrolyte solution B to obtain a solution C; blending the sulfide solution A and the solution C to obtain a negative electrode electrolyte;

[0011] S4, preparing positive electrode electrolyte: preparing positive electrode electrolyte using positive electrode active material and supporting electrolyte;

[0012] S5. Cutting either the graphite felt or the carbon felt to obtain positive and negative electrode materials;

[0013] S6, respectively filling the electrolytes prepared in S3 and S4 into liquid storage tanks to obtain positive and negative electrode liquid storage tanks;

[0014] S7. Assemble the diaphragm, positive and negative electrode materials, filter, and positive and negative electrode storage tanks into a sulfur-based liquid flow battery.

[0015] Furthermore, the alkaline solution in S1 includes any one of KOH solution or NaOH solution; the temperature of ionization treatment is 40-80° C.; the time is 1-3 h; and the ion exchange membrane is any one of Nafion membrane, SPEEK membrane, and SPEEK composite membrane.

[0016] Furthermore, the sulfide in S3 includes a combination of one or both of potassium polysulfide and sodium sulfide; the redox mediator molecule is a redox pair having a standard electrode potential between -0.48 V and -0.28 V under neutral conditions, and the redox mediator molecule is a redox pair having a standard potential between -0.8 V and -0.075 V under alkaline conditions, including one or more combinations of vitamin B and its derivatives, viologen and its derivatives, anthraquinone and its derivatives.

[0017] Furthermore, the positive electrode active material in S4 includes any one of ferrocyanide, ferrocyanide, iodide, ferrocene derivatives or nitrogen oxides.

[0018] Furthermore, the supporting electrolytes in S3 and S4 are one or more combinations of KCl, KBr, NaCl, and NaBr under neutral conditions, and are one or more combinations of KOH and NaOH under alkaline conditions.

[0019] Further, it is characterized in that the molar concentration of sulfide in the negative electrode electrolyte in S3 is 0.1~15M, and the molar concentration of redox mediator molecules is 1.0~200mM;

[0020] In S4, when the positive electrode active substance is ferrocyanide or ferrocyanide, the molar concentration of the positive electrode active substance is 0.1~0.4 M, when the positive electrode active substance is iodide, the molar concentration of the positive electrode active substance is 0.1~8 M, when the positive electrode active substance is a ferrocene derivative, the molar concentration of the positive electrode active substance is 0.1~0.5 M; when the positive electrode active substance is a nitrogen oxide, the molar concentration of the positive electrode active substance is 0.1~0.5 M.

[0021] Furthermore, when vitamin B and its derivatives are used as redox mediator molecules, a light shield is used to shield the negative electrode electrolyte in S7.

[0022] A molecularly driven high-performance sulfur-based liquid flow battery prepared by the above-mentioned liquid flow battery preparation method.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention adds a standard electrode potential of S2 to the negative electrode electrolyte of the sulfur-based liquid flow battery. 2- / S 2- The redox mediator molecules with redox peak potentials between -0.48 V and -0.08 V (vs. SHE) under neutral conditions and -0.8 V to -0.075 V (vs. SHE) under alkaline conditions can catalyze S2 2- / S 2- The redox reaction of S2 2- / S 2- The kinetic process of redox reactions can improve the energy efficiency, cycle stability and cycle life of sulfur-based flow batteries.

[0025] 2. The filter used in the present invention can effectively filter out some insoluble matter generated during the battery cycle, avoid blockage inside the battery and the circulation pipeline, and effectively improve the cycle stability of the sulfur-based liquid flow battery.

[0026] 3. The vitamin B proposed in the present invention is green and environmentally friendly as a redox mediator molecule, and can effectively improve the stability of sulfur-based batteries. Due to the photosensitivity of vitamin B, a light shield is designed to protect the negative electrode electrolyte from light, effectively preventing vitamin B from being decomposed by light, so as to improve the stability of sulfur-based liquid flow batteries.

[0027] 4. The present invention proposes viologen as a redox mediator molecule, which can regulate chemical properties such as solubility and potential through molecular design, and has low cost and can effectively improve the stability of sulfur-based batteries.

[0028] 5. The present invention proposes anthraquinone as a redox mediator molecule, which is simple to synthesize and the compound raw materials are cheap and readily available. The solubility potential can be regulated by molecular design, effectively improving the stability of sulfur-based batteries.

[0029] The present invention effectively improves the energy efficiency, cycle stability and cycle life of the sulfur-based liquid flow battery by adding redox media molecules to the negative electrode electrolyte and installing a filter in the negative electrode circulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a CV diagram of the negative electrode active material in Example 1 of the present invention.

[0032] Figure 2 It is the CV diagram of the redox mediator molecule in Example 1 of the present invention.

[0033] Figure 3 It is a comparison diagram of the charge and discharge curves of the iron-sulfur-riboflavin sodium phosphate flow battery in Example 1 of the present invention.

[0034] Figure 4 This is a comparison chart of the efficiency and performance of the iron-sulfur-riboflavin sodium phosphate flow battery in Example 1 of the present invention.

[0035] Figure 5 This is a comparison chart of the capacity retention rates of the iron-sulfur-riboflavin sodium phosphate flow battery in Example 1 of the present invention.

[0036] Figure 6 This is the CV graph of the redox mediator molecule riboflavin in Example 2 of the present invention.

[0037] Figure 7 This is a comparison chart of the efficiency and performance of the iron-sulfur-riboflavin flow battery in Example 2 of the present invention.

[0038] Figure 8 This is a comparison chart of the capacity retention rate of the iron-sulfur-riboflavin flow battery in Example 2 of the present invention.

[0039] Fig. 9 This is a comparison chart of the efficiency and performance of the iron-sulfur-nicotinamide adenine dinucleoside flow battery in Example 3 of the present invention.

[0040] Fig.103 is a comparison chart of the capacity retention rate of the iron-sulfur-nicotinamide adenine dinucleoside flow battery in Example 3 of the present invention.

[0041] Fig.11 This is a comparison chart of the efficiency and performance of the sulfur-iodine-riboflavin sodium phosphate flow battery in Example 4 of the present invention.

[0042] Fig.12 This is a comparison chart of the capacity retention rates of the sulfur-iodine-riboflavin sodium phosphate flow battery in Example 4 of the present invention.

[0043] Fig.13 This is a comparison chart of the efficiency performance of the ferrocene / sulfur-riboflavin sodium phosphate flow battery in Example 5 of the present invention.

[0044] Fig.14 This is a comparison chart of the capacity retention rate of the ferrocene / sulfur-riboflavin sodium phosphate flow battery in Example 5 of the present invention.

[0045] Fig.15 This is a comparison chart of the efficiency performance of the TEMPO / sulfur-riboflavin sodium phosphate flow battery in Example 6 of the present invention.

[0046] Fig.16 It is a comparison chart of the capacity retention rate of the TEMPO / sulfur-riboflavin sodium phosphate flow battery in Example 6 of the present invention.

[0047] Fig.17 This is a CV diagram of the negative electrode active material in Example 7 of the present invention.

[0048] Fig.18 CV diagram of the redox mediator molecule in Example 7 of the present invention.

[0049] Fig.19 This is a comparison chart of the efficiency and performance of the iron-sulfur-riboflavin sodium phosphate flow battery in Example 7 of the present invention.

[0050] Fig. 20 This is a comparison chart of the capacity retention rates of the iron-sulfur-riboflavin sodium phosphate flow battery in Example 7 of the present invention.

[0051] Fig.21 It is the CV diagram of the redox mediator molecule in Example 8 of the present invention.

[0052] Fig. 22 This is a comparison chart of the efficiency performance of the iron-sulfur-MV liquid flow battery in Example 8 of the present invention.

[0053] Fig.23 It is a comparison chart of the capacity retention rate of the iron-sulfur-MV liquid flow battery in Example 8 of the present invention.

[0054] Fig.24 It is the CV diagram of the redox mediator molecule in Example 9 of the present invention.

[0055] Fig.25 It is the iron-sulfur-Dex-Vi in Example 9 of the present invention 4+ Efficiency performance comparison chart of flow batteries.

[0056] Fig.26 It is the iron-sulfur-Dex-Vi in Example 9 of the present invention 4+ Comparison chart of capacity retention of flow batteries.

[0057] Fig. 27 This is a comparison chart of the efficiency performance of the iron-sulfur-MVI2 liquid flow battery in Example 10 of the present invention.

[0058] Fig.28 This is a comparison chart of the capacity retention rate of the iron-sulfur-MVI2 liquid flow battery in Example 10 of the present invention.

[0059] Fig.29 This is a cycle performance diagram of the iron-sulfur-MVBr2 liquid flow battery in Example 11 of the present invention.

[0060] Fig.30 The iron-sulfur-PV in Example 12 of the present invention 3+ Graph of the cycling performance of a flow battery.

[0061] Fig.31 This is a cycle performance diagram of the iron-sulfur-BSP-Vi liquid flow battery in Example 13 of the present invention.

[0062] Fig.32 This is the cycle performance diagram of the iron-sulfur-BTMAP-Vi liquid flow battery in Example 14 of the present invention.

[0063] Fig.33 This is a cycle performance diagram of the iron-sulfur-BTMAE-Vi liquid flow battery in Example 15 of the present invention.

[0064] Fig.34 This is a cycle performance diagram of the iron-sulfur-[(Me)(NPr)V]Cl3 liquid flow battery in Example 16 of the present invention.

[0065] Fig.35 This is a cycle performance diagram of the iron-sulfur-EDV-HBCD liquid flow battery in Example 17 of the present invention.

[0066] Fig.36 This is a cycle performance diagram of the iron-sulfur-[(NPr)2V]Br4 liquid flow battery in Example 18 of the present invention.

[0067] Fig.37 This is the cycle performance diagram of the iron-sulfur-((NPr)(SPr)V)Br2 liquid flow battery in Example 19 of the present invention.

[0068] Fig.38This is a cycle performance diagram of the iron-sulfur-[(NPr)2TTz]Cl4 liquid flow battery in Example 20 of the present invention.

[0069] Fig.39 This is a cycle performance diagram of the iron-sulfur-(CBu) V liquid flow battery in Example 21 of the present invention.

[0070] Fig.40 This is the cycle performance diagram of the iron-sulfur-(2HO-V)Br2 liquid flow battery in Example 22 of the present invention.

[0071] Fig.41 This is the cycle performance diagram of the iron-sulfur-BHOP-Vi liquid flow battery in Example 23 of the present invention.

[0072] Fig.42 This is a cycle performance diagram of the sulfur-iodine-MVCl2 liquid flow battery in Example 24 of the present invention.

[0073] Fig.43 This is a cycle performance diagram of the ferrocene / sulfur-(SPr) 2V liquid flow battery in Example 25 of the present invention.

[0074] Fig.44 This is the cycle performance diagram of the ferrocene / sulfur-EV⊂α-CD liquid flow battery in Example 26 of the present invention.

[0075] Fig.45 This is a cycle performance diagram of the TEMPO / sulfur-Diqua flow battery in Example 27 of the present invention.

[0076] Fig.46 This is a cycle performance diagram of the TEMPO / sulfur-1,6-DPAP liquid flow battery in Example 28 of the present invention.

[0077] Fig.47 This is the cycle performance diagram of the TEMPO / sulfur-(TPyTz)Cl6 liquid flow battery in Example 29 of the present invention.

[0078] Fig.48 This is a comparison chart of the efficiency performance of the sulfur-iodine-MV liquid flow battery in Example 30 of the present invention.

[0079] Fig.49 This is a comparison chart of the capacity retention rate of the sulfur-iodine-MV liquid flow battery in Example 30 of the present invention.

[0080] Fig.50 This is a comparison chart of the efficiency performance of the ferrocene / sulfur-MV flow battery in Example 31 of the present invention.

[0081] Fig.51 This is a comparison chart of the capacity retention rate of the ferrocene / sulfur-MV liquid flow battery in Example 31 of the present invention.

[0082] Fig.52 This is a comparison chart of the efficiency performance of the TEMPO / sulfur-MV flow battery in Example 32 of the present invention.

[0083] Fig.53 This is a comparison chart of the capacity retention rates of the TEMPO / sulfur-MV flow battery in Example 32 of the present invention.

[0084] Fig.54 This is the CV diagram of the negative electrode active material in Example 33 of the present invention.

[0085] Fig.55 This is a comparison chart of the efficiency performance of the iron-sulfur-AQDS liquid flow battery in Example 33 of the present invention.

[0086] Fig.56 This is a comparison chart of the capacity retention rate of the iron-sulfur-AQDS liquid flow battery in Example 33 of the present invention.

[0087] Fig.57 This is a comparison chart of the capacity retention rate of the iron-sulfur-AQDS (NH4)2 liquid flow battery in Example 34 of the present invention.

[0088] Fig.58 This is a comparison chart of the capacity retention rate of the iron-sulfur-AQDS (NH4)2 liquid flow battery in Example 34 of the present invention.

[0089] Fig.59 This is a comparison chart of the efficiency performance of the iron-sulfur-PEGAQ liquid flow battery in Example 35 of the present invention.

[0090] Fig.60 This is a comparison chart of the capacity retention rate of the iron-sulfur-PEGAQ liquid flow battery in Example 35 of the present invention.

[0091] Fig.61 This is a comparison chart of the efficiency performance of the iron-sulfur-2,6-DPPEAQ liquid flow battery in Example 36 of the present invention.

[0092] Fig.62 This is a comparison chart of the capacity retention rate of the iron-sulfur-2,6-DPPEAQ liquid flow battery in Example 36 of the present invention.

[0093] Fig.63 This is a comparison chart of the efficiency performance of the iron-sulfur-Lawsone liquid flow battery in Example 37 of the present invention.

[0094] Fig.64 This is a comparison chart of the capacity retention rate of the iron-sulfur-Lawsone liquid flow battery in Example 37 of the present invention.

[0095] Fig.65 This is a comparison chart of the efficiency performance of the sulfur-iodine-AQDS liquid flow battery in Example 38 of the present invention.

[0096] Fig.66 This is a comparison chart of the capacity retention rate of the sulfur-iodine-AQDS liquid flow battery in Example 38 of the present invention.

[0097] Fig.67 This is a comparison chart of the efficiency performance of the ferrocene / sulfur-AQDS liquid flow battery in Example 39 of the present invention.

[0098] Fig.68 This is a comparison chart of the capacity retention rate of the ferrocene / sulfur-AQDS liquid flow battery in Example 39 of the present invention.

[0099] Fig.69 This is a comparison chart of the efficiency performance of the TEMPO / sulfur-MV flow battery in Example 40 of the present invention.

[0100] Fig.70 It is a comparison chart of the capacity retention rate of the TEMPO / sulfur-MV liquid flow battery in Example 40 of the present invention.

[0101] Fig.71 This is the CV diagram of the redox mediator molecule in Example 41 of the present invention.

[0102] Fig.72 This is a comparison chart of the efficiency performance of the iron-sulfur-2,6-DHAQ liquid flow battery in Example 41 of the present invention.

[0103] Fig.73 This is a comparison chart of the capacity retention rate of the iron-sulfur-2,6-DHAQ liquid flow battery in Example 41 of the present invention. DETAILED DESCRIPTION

[0104] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0105] This embodiment accelerates S2 by adding redox mediator molecules to the negative electrode electrolyte. 2- / S 2- The kinetic process of the redox reaction, the installation of a filter in the negative electrode circulation system, and the light-proof treatment of the negative electrode electrolyte to improve the stability of the negative electrode electrolyte can effectively improve the energy efficiency, cycle stability and cycle life of the sulfur-based flow battery. 2- / S 2-The redox couple serves as the active material, ensuring the high energy density of sulfur-based flow batteries. The higher solubility reduces the risk of active material precipitation and clogging the interior of the flow battery and the circulation pipeline. It is safer, more stable, and more adaptable to large-scale batch preparation and application.

[0106] Example 1

[0107] A molecularly driven method for preparing a high-performance sulfur-based flow battery, using vitamin B as a redox mediator molecule, comprises the following steps:

[0108] S1. Preparation of diaphragm materials (the Nafion membrane in this embodiment uses ionized Nafion 212):

[0109] S101, place a Nafion membrane with a length of 7.5 cm and a width of 5.0 cm in a 1.0 M potassium hydroxide aqueous solution at a constant temperature of 60°C for 2 h;

[0110] S102, repeatedly rinse the ionized Nafion membrane with deionized water until it becomes neutral, soak it in deionized water, and set aside.

[0111] S2. Preparation of electrode materials (both the positive and negative electrodes in this embodiment use carbon felt): cut the carbon felt into specifications of 4.5 cm in length, 3.0 cm in width, and 5.5 mm in thickness; and use them as positive and negative electrode materials.

[0112] S3. Preparation of electrolyte and electrochemical test (in this embodiment, the positive electrode active material uses potassium ferrocyanide and sodium ferrocyanide, the negative electrode active material uses potassium polysulfide, the positive and negative electrode supporting electrolytes use KCl, and the redox mediator molecule uses riboflavin sodium phosphate);

[0113] S301, preparation of negative electrode electrolyte: potassium polysulfide and KCl are dissolved in deionized water to prepare solution 1; KCl is dissolved in deionized water to prepare solution 2; riboflavin sodium phosphate is added to solution 2 to prepare solution 3; finally, solution 1 and solution 3 are mixed to prepare negative electrode electrolyte. The molar concentration of potassium polysulfide is 1.5 M, the molar concentration of KCl is 0.5 M, and the molar concentration of riboflavin sodium phosphate is 50 mM.

[0114] S302, preparation of positive electrode electrolyte: Potassium ferrocyanide, sodium ferrocyanide and KCl are dissolved in deionized water to prepare a positive electrode electrolyte. The molar concentration of ferrocyanide is 0.3 M, and the molar concentration of KCl is 1.0 M.

[0115] S303, negative electrode electrolyte electrochemical test:

[0116] a: Active substance CV test solution: potassium polysulfide and KCl were dissolved in deionized water to prepare a potassium polysulfide solution, the molar concentration of the potassium polysulfide solution was 5.0 mM, and the molar concentration of KCl was 1.0 M;

[0117] b: Redox mediator molecule CV test solution: riboflavin sodium phosphate and KCl were dissolved in deionized water to prepare riboflavin sodium phosphate solution, the molar concentration of riboflavin sodium phosphate solution was 1.0 mM, and the molar concentration of KCl was 1.0 M.

[0118] In this embodiment, potassium polysulfide, KCl, and riboflavin sodium phosphate aqueous solution are used as the negative electrode electrolyte, potassium ferrocyanide, sodium ferrocyanide, and KCl are used as the positive electrode electrolyte, carbon felt is used as the positive and negative electrode materials, and the ionized Nafion 212 membrane is used as the diaphragm. The screen is connected to the circulation system, and the negative electrode electrolyte is shaded with a light shield. The key materials are assembled into a modified iron-sulfur liquid flow battery; the battery test system is used for battery testing. The charge and discharge current density is 40mA cm -2 , assembling iron-sulfur flow batteries;

[0119] In the iron-sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with those of the modified iron-sulfur flow battery.

[0120] Using an electrochemical workstation, cyclic voltammetry (CV) tests were performed on the potassium polysulfide solution and riboflavin sodium phosphate solution prepared in Example 1 using a three-electrode system, with a glassy carbon electrode as the working electrode, saturated calomel as the reference electrode, and a platinum mesh as the counter electrode. Figure 1 As shown, S2 2- / S 2- The standard electrode potential under neutral conditions is -0.30 V (vs. SHE), such as Figure 2 As shown in the figure, the standard electrode potential of riboflavin sodium phosphate under neutral conditions (-0.31 V vs. SHE) is between -0.48V and -0.28 V (vs. SHE relative to standard hydrogen electrode), which can be used as a redox mediator molecule in the negative electrode electrolyte of all-neutral sulfur-based flow batteries to accelerate S2 2- / S 2- redox kinetics. Figure 3 Comparison of charge and discharge curves of the original iron-sulfur liquid flow battery and the modified iron-sulfur liquid flow battery prepared in Example 1. After adding riboflavin sodium phosphate, the charge and discharge curves of the original iron-sulfur liquid flow battery and the modified iron-sulfur liquid flow battery are shown in Figure 1. -2 Under this condition, the polarization of iron-sulfur liquid flow battery is reduced and the charge and discharge capacity is effectively improved. Figure 4-5 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 1 is shown at 40 mA cm -2Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0121] Example 2

[0122] The difference from Example 1 is that the redox mediator molecule used in the negative electrode electrolyte is riboflavin; the molar concentration of the negative electrode active substance potassium polysulfide is 15 M, the negative electrode supporting electrolyte is KBr, and the molar concentration of KBr is 0.1 M; SPEEK composite diaphragm is used as the diaphragm material; graphite felt is used as the positive and negative electrode materials; the filter device uses graphite felt, which is connected to the circulation device. The CV test solution is a riboflavin solution; the remaining steps are the same as Example 1.

[0123] like Figure 6 As shown in Figure 2, the standard electrode potential of riboflavin under neutral conditions is -0.31 V (vs. SHE), between -0.48 V and -0.28 V (vs. SHE), which can serve as a redox mediator molecule in the negative electrolyte of all-neutral sulfur-based flow batteries to accelerate S2 2- / S 2- redox kinetics. Figure 7-8 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 2 is shown in Figure 2. -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0124] Example 3

[0125] The difference from Example 1 is that SPEEK membrane is used as the diaphragm material, the ionization treatment solution of the diaphragm is sodium hydroxide, the active substance used in the positive electrode electrolyte is Na2S, and the positive and negative electrode supporting electrolytes are both NaCl. The redox mediator molecule is nicotinamide adenine dinucleoside, and the molar concentration is 10 mM. The filtration device uses carbon felt, which is connected to the circulation device, and the remaining steps are the same as Example 1. Figure 9-10 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 3 is shown in Figure 2 at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that the present invention can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0126] Example 4

[0127] The difference from Example 1 is the preparation of the positive electrolyte: potassium iodide and KBr are dissolved in deionized water to prepare the positive electrolyte. The molar concentration of potassium iodide is 0.1 M, and the molar concentration of KBr is 1.0 M. The molar concentration of the negative active material potassium polysulfide is 0.1 M, the negative supporting electrolyte is KBr, and the molar concentration of KBr is 1.0 M, and the sulfur-iodine liquid flow battery is assembled;

[0128] In the sulfur-iodine flow battery, no redox mediator molecules are added to the negative electrode electrolyte, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with those of the modified sulfur-iodine flow battery. Figure 11-12 The cycle performance diagram of the sulfur-iodine flow battery prepared in Example 4 is shown in Figure 2 at 40 mA cm -2 Under this condition, the efficiency of sulfur-iodine liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0129] Example 5

[0130] The difference from Example 1 is the preparation of the positive electrolyte: Fc-SO3NH4 and KCl are dissolved in deionized water to prepare the positive electrolyte. The molar concentration of Fc-SO3NH4 is 0.1 M, the molar concentration of KCl is 1.0 M, and the molar concentration of the redox mediator molecule is 200 mM. Ferrocene / sulfur flow battery is assembled, and the charge and discharge current density is 20 mA cm -2 , assembling ferrocene / sulfur flow batteries;

[0131] In the ferrocene / sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, carbon felt is used as the negative electrode material, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with those of the modified ferrocene / sulfur flow battery. Figure 13-14 The cycle performance diagram of the sulfur-iodine flow battery prepared in Example 5 is shown in Figure 5. -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0132] Example 6

[0133] The difference from Example 1 is the preparation of the positive electrolyte: 4-OH-TEMPO and KCl are dissolved in deionized water to prepare the positive electrolyte. The molar concentration of 4-OH-TEMPO is 0.1 M, the molar concentration of KCl is 1.0 M, and the molar concentration of the redox mediator molecule is 1 mM. The TEMP / sulfur flow battery is assembled, and the charge and discharge current density is 20 mA cm -2 , assembling TEMPO / sulfur flow batteries;

[0134] In the TEMPO / sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with the modified TEMPO / sulfur flow battery. Figure 15-16 The cycle performance diagram of the sulfur-iodine flow battery prepared in Example 6 is shown at 20 mA cm -2 Under this condition, the efficiency of ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that the present invention can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0135] Example 7

[0136] The difference from Example 1 is that the CV test solutions are different: a: Active substance CV test solution: potassium polysulfide and KCl are dissolved in deionized water to prepare a potassium polysulfide solution, the molar concentration of the potassium polysulfide solution is 5.0 mM, and the molar concentration of KOH is 1.0 M; b: Redox mediator molecule CV test solution: riboflavin sodium phosphate and KOH are dissolved in deionized water to prepare a riboflavin sodium phosphate solution, the molar concentration of the riboflavin sodium phosphate solution is 1.0 mM, and the molar concentration of KOH is 1.0 M. Active substance CV test solution In the CV test, Hg / HgO is used as the reference electrode.

[0137] The supporting electrolyte in the positive and negative electrolytes of the original iron-sulfur liquid flow battery and the modified iron-sulfur liquid flow battery is KOH, and the molar concentration of KOH is 1.0 M. The remaining steps are the same as those in Example 1.

[0138] like Fig.17 As shown, S2 2- / S 2- The standard electrode potential under alkaline conditions is -0.32 V (vs. SHE), such as Fig.18 As shown in Figure 2, the standard electrode potential of riboflavin sodium phosphate under alkaline conditions (-0.52 V vs. SHE) is between -0.8 V and -0.075 V (vs. SHE relative to the standard hydrogen electrode), which can serve as a redox mediator molecule in the negative electrolyte of alkaline sulfur-based flow batteries to accelerate the S2 2- / S 2- redox kinetics.

[0139] Figure 19-20 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 7 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a high-stability alkaline sulfur-based liquid flow battery.

[0140] Example 8

[0141] A molecularly driven high-performance sulfur-based flow battery preparation method, when using viologen and its derivatives as redox media molecules, comprises the following steps:

[0142] S1. Preparation of diaphragm material (ionized Nafion 212 is used in this example);

[0143] S101, place a Nafion membrane with a length of 7.5 cm and a width of 5.0 cm in a 0.1 M potassium hydroxide aqueous solution at a constant temperature of 80°C for 3 h;

[0144] S102, repeatedly rinse the ionized Nafion membrane with deionized water until it becomes neutral, soak it in deionized water, and set aside.

[0145] S2. Preparation of electrode materials (carbon felt is used for both positive and negative electrodes in this embodiment): Carbon felt with a length of 4.5 cm, a width of 3.0 cm, and a thickness of 5.5 mm is used as positive and negative electrode materials.

[0146] S3. Preparation of electrolyte and electrochemical test (in this embodiment, the positive electrode active material uses potassium ferrocyanide and sodium ferrocyanide, the negative electrode active material uses potassium sulfide, the positive and negative electrode supporting electrolytes use KCl, and the redox mediator molecule uses MV);

[0147] S301, preparation of negative electrode electrolyte: potassium polysulfide and KCl are dissolved in deionized water to prepare solution 1; KCl is dissolved in deionized water to prepare solution 2; MV is added to solution 2 to prepare solution 3; finally, solution 1 and solution 3 are mixed to prepare negative electrode electrolyte. The molar concentration of potassium sulfide is 1.5 M, the molar concentration of KCl is 0.5 M, and the molar concentration of MV is 10 mM;

[0148] S302, preparation of positive electrode electrolyte: Potassium ferrocyanide, sodium ferrocyanide and KCl are dissolved in deionized water to prepare a positive electrode electrolyte. The molar concentration of ferrocyanide is 0.3 M, and the molar concentration of KCl is 1.0 M.

[0149] S303, negative electrode electrolyte electrochemical test:

[0150] a: Active substance CV test solution: potassium polysulfide and KCl were dissolved in deionized water to prepare potassium sulfide solution, the molar concentration of potassium sulfide solution was 5.0 mM, and the molar concentration of KCl was 1.0 M;

[0151] b: Redox mediator molecule CV test solution: MV and KCl were dissolved in deionized water to prepare MV solution, the molar concentration of MV solution was 10 mM, and the molar concentration of KCl was 1.0 M.

[0152] In this embodiment, potassium sulfide, KCl, and MV aqueous solution are used as the negative electrode electrolyte, potassium ferrocyanide, sodium ferrocyanide, and KCl are used as the positive electrode electrolyte, carbon felt is used as the positive and negative electrode materials, and ionized Nafion 212 membrane is used as the diaphragm. The screen is connected to the circulation system; the battery test system is used for battery testing. The charge and discharge current density is 40mAcm -2 , assembling iron-sulfur flow batteries;

[0153] No redox mediator molecules are added to the negative electrode electrolyte in the iron-sulfur flow battery, the circulation system is not connected to a filter, and the negative electrode electrolyte is deoxygenated. Other conditions are consistent with those of the modified iron-sulfur flow battery.

[0154] Using an electrochemical workstation, CV tests were performed on the potassium polysulfide solution and MV solution prepared in Example 8 using a three-electrode system, with a glassy carbon electrode as the working electrode, Ag / AgCl as the reference electrode, and a platinum mesh as the counter electrode. Fig.21 As shown in Figure 2, the standard electrode potential of MV under neutral conditions (-0.45 V vs. SHE) is between -0.48 V and -0.28 V (vs. SHE), which can serve as a redox mediator molecule in the negative electrode electrolyte of fully neutral sulfur-based flow batteries to accelerate S2 2- / S 2- redox kinetics.

[0155] Cycling performance of the iron-sulfur liquid flow battery prepared in Example 8 Fig. 22 As shown in the figure, the iron-sulfur liquid flow battery with redox mediator MV added to the negative electrolyte, a mesh connected to the negative circulation system as a filter, and deoxygenation of the negative electrolyte, has a high conductivity at 40 mA cm -2 At the working current density, the battery efficiency is effectively improved and the battery cycle is more stable, such as Fig.23 The results of the examples show that the addition of the redox mediator molecule MV to the negative electrode electrolyte, the connection of the mesh as a filter in the negative electrode circulation system, and the deoxygenation treatment of the negative electrode electrolyte for use in the iron-sulfur liquid flow battery can improve the energy efficiency, cycle stability and cycle life of the iron-sulfur liquid flow battery.

[0156] Example 9

[0157] The difference from Example 8 is that the supporting electrolyte used in the positive and negative electrodes is a mixture of KCl and NaCl, the molar concentration of KCl is 0.5 M, and the molar concentration of NaCl is 0.5 M; the active substance used in the negative electrode electrolyte is a mixture of potassium polysulfide and sodium sulfide, the molar concentration of potassium polysulfide is 1.0 M, and the molar concentration of sodium sulfide is 1.0 M; the redox mediator molecule is Dex-Vi 4+CV test solution is Dex-Vi 4+ Solution; the remaining steps are the same as in Example 8. Fig.24 As shown in Figure 2, the standard electrode potential of riboflavin under neutral conditions is -0.32 V (vs. SHE), between -0.48 V and -0.28 V (vs. SHE), which can serve as a redox mediator molecule in the negative electrolyte of all-neutral sulfur-based flow batteries to accelerate S2 2- / S 2- redox kinetics. Figure 25-26 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 9 is shown in Figure 1 at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0158] Example 10

[0159] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is MVI2; SPEEK composite diaphragm is used as the diaphragm material; graphite felt is used as the positive and negative electrode materials; the filtration device uses graphite felt, which is connected to the circulation device; the remaining steps are the same as Example 8. Figure 27-28 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 10 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0160] Embodiment 11

[0161] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is MVBr2; the remaining steps are the same as Example 8. Fig.29 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 11 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0162] Example 12

[0163] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is PV 3+ ; The remaining steps are the same as in Example 8. Fig.30 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 12 is shown at 40 mA cm -2Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0164] Example 13

[0165] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is BSP-Vi; the remaining steps are the same as Example 8. Fig.31 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 13 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0166] Embodiment 14

[0167] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is BTMAP-Vi; the remaining steps are the same as Example 8. Fig.32 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 14 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0168] Embodiment 15

[0169] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is BTMAE-Vi; the remaining steps are the same as Example 8. Fig.33 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 15 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0170] Example 16

[0171] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is [(Me)(NPr)V]Cl3; the remaining steps are the same as Example 8. Fig.34 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 16 is shown at 40 mAcm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0172] Embodiment 17

[0173] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is EDV-HBCD; the remaining steps are the same as Example 8. Fig.35 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 17 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that the present invention can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0174] Embodiment 18

[0175] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is [(NPr)2V]Br4; the remaining steps are the same as Example 8. Fig.36 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 18 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0176] Embodiment 19

[0177] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is ((NPr)(SPr)V)Br2; the remaining steps are the same as Example 8. Fig.37 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 19 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0178] Embodiment 20

[0179] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is [(NPr)2TTz]Cl4; the remaining steps are the same as Example 8. Fig.38 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 20 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0180] Embodiment 21

[0181] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is (CBu) V; the remaining steps are the same as Example 8. Fig.39The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 21 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0182] Embodiment 22

[0183] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is (2HO-V)Br2; the positive and negative electrode supporting electrolytes are KBr, and the KBr molar concentration is 5.0 M. The remaining steps are the same as Example 8. Fig.40 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 22 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0184] Embodiment 23

[0185] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is BHOP-Vi; the remaining steps are the same as Example 8. Fig.41 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 23 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0186] Embodiment 24

[0187] The difference from Example 8 is that SPEEK membrane is used as the diaphragm material; the ionization treatment solution of the diaphragm is sodium hydroxide; the active substance used in the positive electrode electrolyte is Na2S, and the positive and negative electrode supporting electrolytes are both NaBr; the redox mediator molecule is MVCl2; the positive electrode active material is NaI; carbon felt is used for the negative electrode filter; and the remaining steps are the same as Example 8. Fig.42 The cycle performance diagram of the sulfur-iodine flow battery prepared in Example 24 is shown at 40 mA cm -2 Under this condition, the efficiency of sulfur-iodine liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0188] Embodiment 25

[0189] The difference from Example 8 is that the redox mediator molecule used in the negative electrolyte is (SPr)2V. Preparation of positive electrolyte: BTMAP-Fc and KCl are dissolved in deionized water to prepare the positive electrolyte. The molar concentration of BTMAP-Fc is 0.2 M, and the molar concentration of KCl is 1.0 M; the remaining steps are the same as in Example 8. Assemble the ferrocene / sulfur flow battery, and the charge and discharge current density is 20 mA cm -2 , assembling ferrocene / sulfur flow batteries;

[0190] In the ferrocene / sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, carbon felt is used as the negative electrode material, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with those of the modified ferrocene / sulfur flow battery. Fig.43 The cycling performance diagram of the ferrocene / sulfur flow battery prepared in Example 25 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0191] Embodiment 26

[0192] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is EV⊂α-CD. Preparation of positive electrode electrolyte: BQH-Fc and KCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of BQH-Fc is 0.5 M, and the molar concentration of KCl is 1.0 M; the remaining steps are the same as in Example 6. Assemble the ferrocene / sulfur flow battery, and the charge and discharge current density is 20 mA cm -2 . Assembling a ferrocene / sulfur flow battery;

[0193] In the ferrocene / sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, carbon felt is used as the negative electrode material, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with those of the modified ferrocene / sulfur flow battery. Fig.44 The cycle performance diagram of the ferrocene / sulfur flow battery prepared in Example 26 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0194] Embodiment 27

[0195] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is Diquat. Preparation of positive electrode electrolyte: TEMPO-4-SO4 and KCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of TEMPO-4-SO4 is 0.2M, and the molar concentration of KCl is 1.0 M; the remaining steps are the same as in Example 8. Assemble the TEMPO / sulfur flow battery, and the charge and discharge current density is 20mA cm -2 Assembling TEMPO / sulfur flow batteries;

[0196] In the TEMPO / sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, carbon felt is used as the negative electrode material, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with the modified TEMPO / sulfur flow battery. Fig.45 The cycling performance diagram of the ferrocene / sulfur flow battery prepared in Example 27 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0197] Embodiment 28

[0198] The difference from Example 8 is that the redox mediator molecule used in the negative electrolyte is 1,6-DPAP. Preparation of positive electrolyte: TEMPO-imidazole and KCl are dissolved in deionized water to prepare the positive electrolyte. The molar concentration of TEMPO-imidazole is 0.5 M, and the molar concentration of KCl is 1.0 M; the rest of the steps are the same as in Example 8. Assemble the TEMPO / sulfur flow battery, and the charge and discharge current density is 20 mA cm -2 , assembling TEMPO / sulfur flow batteries;

[0199] In the TEMPO / sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, carbon felt is used as the negative electrode material, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with the modified TEMPO / sulfur flow battery. Fig.46 The cycle performance diagram of the ferrocene / sulfur flow battery prepared in Example 28 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0200] Embodiment 29

[0201] The difference from Example 8 is that the redox mediator molecule used in the negative electrode electrolyte is (TPyTz)Cl6. +-TEMPO and KCl were dissolved in deionized water to prepare the positive electrolyte. + -TEMPO molar concentration is 0.1 M, KCl molar concentration is 1.0 M; the remaining steps are the same as in Example 8. TEMPO / sulfur flow battery is assembled, and the charge and discharge current density is 20 mA cm -2 , assembling TEMPO / sulfur flow batteries;

[0202] In the TEMPO / sulfur flow battery, no redox mediator molecules are added to the negative electrode electrolyte, carbon felt is used as the negative electrode material, the circulation system is not connected to a filter, and the negative electrode is not shielded from light. Other conditions are consistent with the modified TEMPO / sulfur flow battery. Fig.47 The cycling performance diagram of the ferrocene / sulfur flow battery prepared in Example 29 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0203] Embodiment 30

[0204] The difference from Example 8 is the preparation of the positive electrode electrolyte: sodium iodide and NaCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of sodium iodide is 8.0 M, and the molar concentration of NaCl is 0.1 M. The ionization treatment solution of the diaphragm is a sodium hydroxide solution; the negative electrode supporting electrolyte is NaCl, and the positive electrode active material is Na2S; the remaining steps are the same as Example 8. Figure 48-49 The cycle performance diagram of the sulfur-iodine flow battery prepared in Example 30 is shown at 40 mA cm -2 Under this condition, the efficiency of sulfur-iodine liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0205] Embodiment 31

[0206] The difference from Example 8 is the preparation of the positive electrode electrolyte: FcNCl and KCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of FcNCl is 0.1 M, and the molar concentration of KCl is 1.0 M; the remaining steps are the same as Example 8. Figure 50-51 The cycle performance diagram of the ferrocene / sulfur flow battery prepared in Example 31 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0207] Embodiment 32

[0208] The difference from Example 8 is the preparation of the positive electrode electrolyte: 4-OH-TEMPO and KCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of 4-OH-TEMPO is 0.1 M, and the molar concentration of KCl is 1.0 M; the remaining steps are the same as Example 7. Figure 52-53 The cycle performance diagram of the ferrocene / sulfur flow battery prepared in Example 32 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0209] Embodiment 33

[0210] A molecularly driven high-performance sulfur-based flow battery preparation method, when anthraquinone and its derivatives are used as redox media molecules, comprises the following steps:

[0211] S1. Preparation of diaphragm material (ionized SPEEK is used in this embodiment);

[0212] S101, place a SPEEK membrane with a length of 7.5 cm and a width of 5.0 cm in a 2.0 M potassium hydroxide aqueous solution at a constant temperature of 40°C for 1 h;

[0213] S102. Rinse the ionized SPEEK membrane repeatedly with deionized water until it becomes neutral, and soak it in deionized water for later use.

[0214] S2. Preparation of electrode materials (carbon felt is used for both positive and negative electrodes in this embodiment): Carbon felt with a length of 4.5 cm, a width of 3.0 cm, and a thickness of 5.5 mm is used as positive and negative electrode materials.

[0215] S3. Preparation of electrolyte and electrochemical test (in this embodiment, the positive electrode active material uses potassium ferrocyanide and sodium ferrocyanide, the negative electrode active material uses potassium polysulfide, the positive and negative electrode supporting electrolytes use KCl, and the redox mediator molecule uses AQDS);

[0216] S301, preparation of negative electrode electrolyte: potassium polysulfide and KBr are dissolved in deionized water to prepare solution 1; KBr is dissolved in deionized water to prepare solution 2; AQDS is added to solution 2 to prepare solution 3; finally, solution 1 and solution 3 are mixed to prepare negative electrode electrolyte. The molar concentration of potassium polysulfide is 1.5 M, the molar concentration of KBr is 0.5 M, and the molar concentration of AQDS is 10 mM;

[0217] S302, preparation of positive electrode electrolyte: dissolving potassium ferrocyanide, sodium ferrocyanide and KBr in deionized water to prepare positive electrode electrolyte. The molar concentration of ferrocyanide is 0.3 M, and the molar concentration of KBr is 1.0 M.

[0218] S303, negative electrode electrolyte electrochemical test:

[0219] a: Active substance CV test solution: Potassium polysulfide and KBr were dissolved in deionized water to prepare a potassium polysulfide solution with a molar concentration of 5.0 mM and a molar concentration of 1.0 M KBr.

[0220] b: Redox mediator molecule CV test solution: AQDS and KBr were dissolved in deionized water to prepare AQDS solution, the molar concentration of AQDS solution was 1.0 mM, and the molar concentration of KBr was 1.0 M.

[0221] In this embodiment, potassium polysulfide, KBr, and AQDS aqueous solution are used as the negative electrolyte, potassium ferrocyanide, sodium ferrocyanide, and KBr are used as the positive electrolyte, carbon felt is used as the positive and negative electrode materials, and the ionized SPEEK membrane is used as the diaphragm. The screen is connected to the circulation system, and the key materials are used to assemble a modified iron-sulfur liquid flow battery; the battery test system is used for battery testing. The charge and discharge current density is 40mA cm -2 , assembling iron-sulfur flow batteries;

[0222] No redox mediator molecules are added to the negative electrode electrolyte in the iron-sulfur flow battery, the circulation system is not connected to a filter, and the negative electrode electrolyte is deoxygenated. Other conditions are consistent with those of the modified iron-sulfur flow battery.

[0223] Using an electrochemical workstation, CV tests were performed on the potassium polysulfide solution and AQDS solution prepared in Example 33 using a three-electrode system, with a glassy carbon electrode as the working electrode, saturated calomel as the reference electrode, and a platinum mesh as the counter electrode. Fig.54 As shown in Figure 2, the standard electrode potential of AQDS under neutral conditions is -0.25 V vs. SHE, and the potential is between -0.48 V and -0.28 V (vs. SHE). It can be used as a redox mediator molecule in the negative electrode electrolyte of all-neutral sulfur-based flow batteries to accelerate S2 2- / S 2- redox kinetics.

[0224] Cycling performance of the iron-sulfur liquid flow battery prepared in Example 33 Fig.55 As shown in the figure, the iron-sulfur liquid flow battery with redox mediator molecule AQDS added to the negative electrolyte, a mesh connected to the negative circulation system as a filter, and deoxygenation of the negative electrolyte, has a high conductivity at 40 mA cm -2At the working current density, the battery efficiency is effectively improved and the battery cycle is more stable, such as Fig.56 The results of the embodiment show that the addition of the redox mediator molecule AQDS to the negative electrode electrolyte, the connection of the mesh as a filter in the negative electrode circulation system, and the deoxygenation treatment of the negative electrode electrolyte for use in the iron-sulfur liquid flow battery can improve the energy efficiency, cycle stability and cycle life of the iron-sulfur liquid flow battery.

[0225] Embodiment 34

[0226] The difference from Example 33 is that Nafion 212 membrane is used as the diaphragm material, and the ionization treatment solution of the diaphragm is sodium hydroxide; the active substance used in the positive electrode electrolyte is Na2S, the negative electrode supporting electrolyte concentration is 0 M, and the positive electrode supporting electrolyte is NaCl; the redox mediator molecule is AQDS(NH4)2; the filtration device uses carbon felt, which is connected to the circulation device; the remaining steps are the same as Example 33. Figure 57-58 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 34 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0227] Embodiment 35

[0228] The difference from Example 33 is that SPEEK composite diaphragm is used as diaphragm material, the positive and negative supporting electrolytes are a mixture of KBr and NaBr, the molar concentration of KBr is 0.5 M, the molar concentration of NaBr is 0.5 M, and the redox mediator molecule is PEGAQ; the remaining steps are the same as Example 33. Graphite felt is used as the positive and negative electrode materials; the filtering device uses graphite felt, which is connected to the circulation device. Figures 59-60 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 35 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0229] Embodiment 36

[0230] The difference from Example 33 is that the concentration of the negative electrode supporting electrolyte is 0 M. The redox mediator molecule is 2,6-DPPEAQ; and the remaining steps are the same as Example 33. Figure 61-62 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 36 is shown at 40 mA cm -2Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0231] Embodiment 37

[0232] The difference from Example 33 is that the diaphragm uses a negative electrode supporting electrolyte with a concentration of 0 M. The redox mediator molecule is Lawsone; and the remaining steps are the same as in Example 33. Figure 63-64 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 37 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0233] Embodiment 38

[0234] The difference from Example 33 is the preparation of the positive electrode electrolyte: potassium iodide and KCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of potassium iodide is 0.5 M, and the molar concentration of KCl is 1.0 M; the remaining steps are the same as Example 33. Figures 65-66 The cycle performance diagram of the sulfur-iodine flow battery prepared in Example 38 is shown at 40 mA cm -2 Under this condition, the efficiency of sulfur-iodine liquid flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based liquid flow battery.

[0235] Embodiment 39

[0236] The difference from Example 33 is the preparation of the positive electrode electrolyte: FcN2Br2 and KCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of FcN2Br2 is 0.1 M, and the molar concentration of KCl is 1.0 M; the remaining steps are the same as Example 33. Figures 67-68 The cycling performance diagram of the ferrocene / sulfur flow battery prepared in Example 39 is shown at 20 mA cm -2 Under this condition, the efficiency of the ferrocene / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0237] Embodiment 40

[0238] The difference from Example 33 is the preparation of the positive electrode electrolyte: TEMPTMA and KCl are dissolved in deionized water to prepare the positive electrode electrolyte. The molar concentration of TEMPTMA is 0.1 M, and the molar concentration of KOH is 1.0 M; the remaining steps are the same as Example 33. Figures 69-70The cycle performance diagram of the TEMPO / sulfur flow battery prepared in Example 40 is shown at 20 mA cm -2 Under this condition, the efficiency of TEMPO / sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is also effectively improved. The results show that this embodiment can effectively construct a highly stable fully neutral sulfur-based flow battery.

[0239] Embodiment 41

[0240] The difference from Example 33 is that the CV test solutions are different: a: Active substance CV test solution: Potassium polysulfide and KCl are dissolved in deionized water to prepare a potassium sulfide solution, the molar concentration of the potassium sulfide solution is 5.0 mM, and the molar concentration of NaOH is 1.0 M; b: Redox mediator molecule CV test solution: 2,6-DHAQ and NaOH are dissolved in deionized water to prepare a 2,6-DHAQ solution, the molar concentration of the 2,6-DHAQ solution is 1.0 mM, and the molar concentration of NaOH is 1.0 M.

[0241] The supporting electrolyte in the positive and negative electrolytes of the original iron-sulfur liquid flow battery and the modified iron-sulfur liquid flow battery is NaOH, and the molar concentration of NaOH is 1.0 M. The remaining steps are the same as those in Example 33.

[0242] like Fig.71 As shown in the figure, the standard electrode potential of 2,6-DHAQ under alkaline conditions (-0.72 V vs. SHE) is between -0.8 V and -0.075 V (vs. SHE relative to the standard hydrogen electrode), which can serve as a redox mediator molecule in the negative electrolyte of alkaline sulfur-based flow batteries to accelerate the S2 2- / S 2- redox kinetics.

[0243] Figure 72-73 The cycle performance diagram of the iron-sulfur liquid flow battery prepared in Example 41 is shown at 40 mA cm -2 Under this condition, the efficiency of the iron-sulfur flow battery is effectively improved, the battery cycle is more stable, and the cycle life is effectively improved. The results show that this embodiment can effectively construct a high-stability alkaline sulfur-based flow battery. The above embodiment only shows some of the raw material implementation methods. In this embodiment, the sulfide can be one or more combinations of potassium polysulfide and sodium sulfide.

[0244] In some specific embodiments, the redox mediator molecule is a redox pair with a standard electrode potential between -0.48 V and -0.28 V under neutral conditions, and the redox mediator molecule is a redox pair with a standard potential between -0.8 V and -0.075 V under alkaline conditions, including one or more combinations of vitamin B, viologen and its derivatives, anthraquinone and its derivatives; specifically, vitamin B includes one or more combinations of nicotinamide adenine dinucleotide (-0.32 V vs. SHE), riboflavin (flavin mononucleotide (-0.35 V vs. SHE), riboflavin sodium phosphate (-0.31 V vs. SHE), riboflavin sodium phosphate (-0.52 V vs. SHE) under alkaline conditions; viologen and its derivatives include MV (-0.45 V vs. SHE), MVCl2 (-0.45 V vs. SHE), MVI2 (-0.46 V vs. SHE), MVBr2 (-0.45 V vs. SHE), PV 3+ (-0.28 V vs. SHE), BSP-Vi (-0.39 V vs. SHE), BTMAP-Vi (-0.358V vs. SHE, -0.39V vs. SHE,), BTMAE-Vi (-0.40 V vs. SHE), [(Me)(NPr)V]Cl3 (-0.39 V vs. SHE), EDV-HBCD (-0.39 V vs. SHE), [(NPr)2V]Br4 (-0.35 V vs. SHE), ((NPr)(SPr)V)Br2 (-0.37V vs. SHE), [(NPr)2TTz]Cl4 (-0.44V vs. SHE), Dex-Vi 4+(-0.322 V vs. SHE), (CBu) V (-0.43 V vs. SHE), (2HO-V)Br2 (-0.40 V vs. SHE), BHOP-Vi (-0.43 V vs. SHE), (SPr)2V (-0.43 V vs. SHE), EV⊂α-CD (-0.37 V vs. SHE), Diquat (-0.38 V vs. SHE), 1,6-DPAP (-0.56 V vs. SHE), (TPyTz)Cl6 (-0.25 V vs. SHE, -0.44 V vs. SHE); anthraquinone and its derivatives include AQDS (-0.25 V vs. SHE), AQDS(NH4)2 (-0.2 V vs. SHE), PEGAQ (-0.43 V vs. SHE), 2,6-DPPEAQ (-0.47 V vs. SHE) under neutral conditions. vs. SHE), Lawsone (-0.45 V vs. SHE), and 2,6-DHAQ under alkaline conditions (-0.70 V vs. SHE).

[0245] In some specific embodiments, the positive electrode electrolyte is composed of a positive electrode active substance and a supporting electrolyte; the active substance of the positive electrode electrolyte is any one of ferrocyanide, ferrocyanide, iodide, ferrocene derivatives or nitrogen oxides;

[0246] In some specific embodiments, the supporting electrolyte is one or more combinations of KCl, KBr, NaCl, NaBr, KOH, and NaOH;

[0247] In some specific embodiments, the ferrocyanide is a combination of one or more of potassium ferrocyanide and sodium ferrocyanide;

[0248] In some specific embodiments, the ferrocyanide is a combination of one or more of potassium ferrocyanide and sodium ferrocyanide;

[0249] In some specific embodiments, the iodide is one or more combinations of potassium iodide and sodium iodide;

[0250] In some specific embodiments, the ferrocene derivative is one or more combinations of Fc-SO3NH4, FcNCl, FcN2Br2, BTMAP-Fc, and BQH-Fc;

[0251] In some specific embodiments, the nitrogen oxide compound is 4-OH-TEMPO, TMAP-TEMPO, TEMPTMA, TEMPO-4-SO4, TEMPO-imidazole, g + - one or more combinations of TEMPO;

[0252] The above examples only show the partial addition amounts of the raw materials. In this embodiment, the molar concentration of sulfide in the negative electrode electrolyte can be 0.1-15M, the molar concentration of the supporting electrolyte can be 0-5M, and the molar concentration of the redox mediator molecule can be 1.0-200mM; the molar concentration of ferrocyanide in the positive electrode electrolyte can be 0.1-0.4M, the molar concentration of ferrocyanide can be 0.1-0.4M, the molar concentration of iodide can be 0.1-8M, the molar concentration of ferrocene derivatives can be 0.1-0.5M, and the molar concentration of nitrogen oxides can be 0.1-0.5M.

[0253] In some specific embodiments, when vitamin B is used as a redox mediator molecule, the flow battery needs to operate under light-proof conditions.

[0254] In some specific embodiments, the positive electrode supporting electrolyte is the same as the negative electrode supporting electrolyte; the diaphragm is an ion exchange membrane ionized with an alkaline solution; the ion exchange membrane is one of a Nafion membrane, a SPEEK membrane, and a SPEEK composite diaphragm.

[0255] The present invention adds a sulfur-based liquid flow battery negative electrode electrolyte having a standard electrode potential of S2 under neutral conditions. 2- / S 2- The redox mediator molecules with a redox peak potential between -0.48 V and -0.08 V (vs. SHE) and a standard electrode potential between -0.8 V and -0.075 V (vs. SHE) under alkaline conditions can catalyze S2 2- / S 2- The redox reaction of S2 2- / S 2- The kinetic process of redox reaction can improve the energy efficiency, cycle stability and cycle life of sulfur-based flow batteries. The principle is as follows:

[0256] The redox mediator molecules act as electrodes and redox active species (S2 2- / S 2- ) and transfer electrons to the redox active species (S2 2- / S 2- ), thereby promoting S2 2- / S 2-redox reaction.

[0257] (1) When the standard electrode potential of the redox mediator molecule is between -0.48 V and -0.28 V (vs. SHE) under neutral conditions, or between -0.8 V and -0.36 V (vs. SHE) under alkaline conditions, the redox mediator molecule is first reduced to a reduced state at the electrode, and then the reduced state mediator molecule reacts with S2 2- Chemical reaction occurs, promoting S2 2- Restore to S 2- , generating oxidized mediator molecules, which are then regenerated into reduced mediator molecules through electrochemical reactions on the electrodes, and then react with S2 2- reaction, achieving stable electrochemical / chemical cycles and sustained catalysis. This cycle effectively catalyzes S 2- / S2 2- The restoration process speeds up S 2- / S2 2- Redox kinetics.

[0258] (2) When the standard electrode potential of the redox mediator molecule is between -0.28 V and -0.08 V (vs. SHE) under neutral conditions, or between -0.36 V and -0.075 V (vs. SHE) under alkaline conditions, as shown in Formula 3-4, the redox mediator molecule is oxidized to an oxidized mediator molecule on the electrode. Subsequently, the oxidized mediator molecule reacts with S 2- A chemical reaction occurs to promote S 2- Oxidized to S2 2- , generating reduced mediator molecules, which are then regenerated into oxidized mediator molecules through electrochemical reactions on the electrodes, and then react with S 2- reaction, achieving stable electrochemical / chemical cycles and sustained catalysis. This cycle effectively catalyzes S 2- / S2 2- The oxidation process of S 2- / S2 2- Redox kinetics.

[0259] (3) When the standard electrode potential of the redox mediator molecule is equal to -0.28 V vs. SHE under neutral conditions or -0.36 V (vs. SHE) under alkaline conditions, the actual potential of the molecule will change due to the Nernst potential, that is, as the ratio of the oxidized and reduced species in the electrochemical reaction changes, it follows the Nernst equation:

[0260]

[0261] Where E is the actual potential of the molecule, E 0 is the standard electrode potential of the molecule, R is the molar gas constant; T is the reaction temperature; n is the number of electrons transferred in the reaction, F is the Faraday constant, α re is the activity of the reduced molecule, α ox is the activity of the oxidized molecule.

[0262] As the battery operates, the oxidized and reduced states of the redox mediator molecules change, and the potential increases or decreases accordingly. 2- / S 2- After the potential difference is generated, it can be connected with S2 2- / S 2- react with S2 2- / S 2- Energy exchange between them catalyzes S2 2- / S 2- redox process.

[0263] In short, the standard electrode potential is slightly lower than S2 2- / S 2- The redox mediator molecule, whose reduced state can spontaneously react with the oxidized state of sulfide (S2 2- ) chemical reaction occurs, promoting S2 2- Restore to S 2- ; Standard electrode potential is slightly higher than S2 2- / S 2- The redox mediator molecule, whose oxidized state can spontaneously react with the reduced state of sulfide (S 2- ) chemical reaction occurs, promoting S 2- Oxidized to S2 2- ; Standard electrode potential and S2 2- / S 2- The same redox mediator molecule can promote S using the Nernst equation 2- / S2 2 redox reaction.

[0264] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0265] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for preparing a molecularly driven high-performance sulfur-based flow battery, characterized in that: The following steps are involved: S1. preparing a diaphragm: immersing an ion exchange membrane in an alkaline solution for ionization treatment; S2, rinse the deionized ion exchange membrane with deionized water until it becomes neutral, and soak it in deionized water for later use; S3, preparing a negative electrode electrolyte: using deionized water and sulfide to prepare a sulfide solution A, using a supporting electrolyte and deionized water to prepare a negative electrode supporting electrolyte solution B, adding a redox mediator molecule to the negative electrode supporting electrolyte solution B to obtain a solution C; blending the sulfide solution A and the solution C to obtain a negative electrode electrolyte; The sulfide includes one or a combination of potassium polysulfide and sodium sulfide; the redox mediator molecule is a redox pair with a standard electrode potential between -0.48 V and -0.28 V under neutral conditions, and the redox mediator molecule is a redox pair with a standard potential between -0.8 V and -0.075 V under alkaline conditions, including one or more combinations of vitamin B and its derivatives, viologen and its derivatives, anthraquinone and its derivatives; The anthraquinone and its derivatives include one or more combinations of AQDS, -0.25 V vs. SHE, AQDS(NH4)2, -0.2 V vs. SHE, PEGAQ, -0.43 V vs. SHE, 2,6-DPPEAQ, -0.47 V vs. SHE, Lawsone, -0.45 V vs. SHE under neutral conditions, and 2,6-DHAQ, -0.70 V vs. SHE under alkaline conditions; Vitamin B including nicotinamide adenine dinucleotide, -0.32 V vs. SHE, riboflavin including flavin mononucleotide, -0.35 V vs. SHE, riboflavin sodium phosphate, -0.31 V vs. SHE, one or more combinations thereof, riboflavin sodium phosphate under alkaline conditions, -0.52 V vs. SHE; Viologen and its derivatives include MV, -0.45 V vs. SHE, MVCl2, -0.45 V vs. SHE, MVI2, -0.46 V vs. SHE, MVBr2, -0.45 V vs. SHE, PV 3+ , -0.28 V vs. SHE, BSP-Vi, -0.39 V vs. SHE, BTMAP-Vi, -0.358V vs. SHE, -0.39V vs. SHE, BTMAE-Vi, -0.40 V vs. SHE, [(Me)(NPr)V]Cl3, -0.39 V vs. SHE, EDV-HBCD, -0.39 V vs. SHE, [(NPr)2V]Br4, -0.35 V vs. SHE, ((NPr)(SPr)V)Br2, -0.37 V vs. SHE, [(NPr)2TTz]Cl4, -0.44V vs. SHE, Dex-Vi 4+ , -0.322 V vs. SHE, (CBu) V, -0.43 V vs. SHE, (2HO-V)Br2, -0.40 V vs. SHE, BHOP-Vi, -0.43 Vvs. SHE, (SPr)2V, -0.43 V vs. SHE, EV⊂α-CD, -0.37 V vs. SHE, Diquat, -0.38 V vs. SHE, 1,6-DPAP, -0.56 V vs. SHE, (TPyTz)Cl6, -0.25 V vs. SHE, -0.44 V vs. SHE; S4, preparing positive electrode electrolyte: preparing positive electrode electrolyte using positive electrode active material and supporting electrolyte; The positive electrode active material in S4 includes any one of ferrocyanide, ferrocyanide, iodide, ferrocene derivatives or nitrogen oxides; The supporting electrolytes in S3 and S4 are one or more combinations of KCl, KBr, NaCl, and NaBr under neutral conditions; and one or more combinations of KOH and NaOH under alkaline conditions; S5. Cutting either the graphite felt or the carbon felt to obtain positive and negative electrode materials; S6, respectively filling the electrolytes prepared in S3 and S4 into liquid storage tanks to obtain positive and negative electrode liquid storage tanks; S7, assembling the diaphragm, positive and negative electrode materials, the filter, and the positive and negative electrode storage tanks into a sulfur-based liquid flow battery; The filter includes any one of a screen and carbon felt; When vitamin B and its derivatives are used as redox mediator molecules, a light shield is used to shield the negative electrode electrolyte; The molar concentration of sulfide in the negative electrode electrolyte in S3 is 0.1~15M, and the molar concentration of redox mediator molecules is 1.0~200mM; In S4, when the positive electrode active substance is ferrocyanide or ferrocyanide, the molar concentration of the positive electrode active substance is 0.1~0.4M, when the positive electrode active substance is iodide, the molar concentration of the positive electrode active substance is 0.1~8M, when the positive electrode active substance is a ferrocene derivative, the molar concentration of the positive electrode active substance is 0.1~0.5M; when the positive electrode active substance is a nitrogen oxide compound, the molar concentration of the positive electrode active substance is 0.1~0.5M.

2. The method for preparing a molecularly driven high-performance sulfur-based flow battery according to claim 1, characterized in that: The alkaline solution in S1 includes any one of KOH solution or NaOH solution; the temperature of ionization treatment is 40-80° C.; the time is 1-3 h; and the ion exchange membrane is any one of Nafion membrane, SPEEK membrane, and SPEEK composite membrane.

3. A molecule-driven high-performance sulfur-based liquid flow battery prepared by the method for preparing a molecule-driven high-performance sulfur-based liquid flow battery as described in any one of claims 1 to 2.

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