Long-circulation alkaline zinc-manganese flow battery and electrolyte preparation method thereof

Abstract

The invention belongs to the technical field of electrochemical energy storage, and particularly relates to a long-circulation alkaline zinc-manganese flow battery electrolyte as well as a preparation method and application thereof. The alkaline zinc-manganese flow battery electrolyte provided by the invention comprises the supporting electrolyte and the additive, and active substances in the additive and the electrolyte play a synergistic effect, so that dendritic crystal growth and self-corrosion of an anode of a zinc-manganese flow battery are effectively inhibited; according to the alkaline zinc-manganese flow battery electrolyte, under the current density of 80mA cm <-2 >, the coulombic efficiency reaches 97.1%, the energy efficiency reaches 85%, the cycle life can be prolonged from 45h to 160h, the problem of short cycle life caused by non-uniform zinc deposition of a traditional zinc-manganese flow battery is solved, and the alkaline zinc-manganese flow battery electrolyte has the characteristics of low cost, environment friendliness and simple process.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to a long-cycle alkaline zinc-manganese flow battery using urea as an electrolyte additive and a preparation method thereof. Background Art

[0002] Alkaline zinc-manganese flow batteries (AZFBs) are considered an ideal candidate technology for large-scale energy storage due to their advantages such as high safety, low cost and high energy density. However, their practical application is limited by the problems of dendrite growth and dead zinc formation at the zinc negative electrode. In traditional electrolytes, zinc ions exist in the form of Zn(OH)2-4 in alkaline solutions. During charging, the two-dimensional diffusion of zinc ions on the electrode surface can easily lead to uneven deposition, forming dendrites that pierce the ion exchange membrane and cause short circuit risks. At the same time, the self-corrosion and hydrogen evolution reaction of zinc in alkaline solutions will reduce the Coulombic efficiency and shorten the battery life.

[0003] In the prior art, CN 116247262 A, an alkaline zinc-manganese flow battery, uses MnO4 - / MnO4 2- In order to solve the manganese disproportionation problem existing when the active material is used, further introducing appropriate additives (ethylenediaminetetraacetic acid (EDTA), aminotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA)) into the positive electrode electrolyte can significantly inhibit manganese disproportionation and improve battery cycle stability and voltage efficiency. However, the test conditions of this battery are 40mA·cm -2 The charge and discharge experiments were conducted under the current density of 1000 nm and 1000 nm, and the three major efficiencies of the battery were generally high. This shows that there is still room for optimization of the battery. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-performance electrolyte that can achieve high performance, dendrite-free and long life of alkaline zinc-manganese liquid flow batteries.

[0005] In response to the uneven deposition of zinc in alkaline electrolytes to form dendrites that lead to battery short circuits, as well as the self-corrosion of zinc electrodes in alkaline solutions mentioned in the background art, the present invention provides a dendrite-free, long-life, and high-energy-density zinc-manganese flow battery.

[0006] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0007] An electrolyte for a long-cycle alkaline zinc-manganese flow battery comprises a negative electrode electrolyte and a positive electrode electrolyte, wherein the negative electrode electrolyte comprises a complex solution formed by mixing a zinc precursor, an organic additive and a strong base, wherein the organic additive comprises one of urea, ethylenediaminetetraacetic acid (EDTA), N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine, and sodium 2,6-naphthalene disulfonate, and the zinc precursor is dissolved in the strong base to generate Zn(OH)42- The positive electrode electrolyte includes a mixed solution formed by mixing permanganate and a strong base.

[0008] Furthermore, the zinc precursor in the negative electrode electrolyte is at least one of zinc oxide, zinc chloride, zinc iodide, zinc bromide, and zinc sulfate.

[0009] Furthermore, in the positive electrode electrolyte, the permanganate is at least one of sodium permanganate and potassium permanganate.

[0010] Furthermore, the strong base in the negative electrode electrolyte and the positive electrode electrolyte is at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide.

[0011] Furthermore, the zinc precursor is dissolved in a strong base to generate Zn(OH)4 2- The molar concentration of the organic additive is 0.1 to 1 mol / L, and the molar concentration of the strong base is 6 mol / L.

[0012] A method for preparing an electrolyte for a long-cycle alkaline zinc-manganese flow battery comprises the following steps:

[0013] (1) Prepare two strong alkaline solutions as supporting electrolyte solutions for the negative electrode electrolyte and the positive electrode electrolyte, respectively, and then cool them to room temperature for later use;

[0014] (2) Add zinc precursor to one of the strong base solutions, and mix the zinc precursor and the strong base evenly under water bath heating and magnetic stirring to obtain a solution containing the active substance Zn(OH)4 2- The solution was cooled to room temperature for later use;

[0015] (3) Add the organic additive to step (2) and stir until it is completely dissolved to obtain a mixture containing the organic additive and the active substance Zn(OH)4 2- Compound negative electrode electrolyte,

[0016] (4) Add permanganate to another strong base solution and wait for it to cool to room temperature to obtain a solution containing the active substance MnO 4- of the positive electrode electrolyte.

[0017] Furthermore, in the step (1), the OH - The concentration of the active substance Zn(OH)4 in step (2) is 6 mol / L. 2- The concentration is 0.1-1 mol L -1 ; The active material MnO in step (3) 4- The concentration is 0.1-1 mol L -1 ,

[0018] Furthermore, the strong base is one of sodium hydroxide, potassium hydroxide and lithium hydroxide, the zinc precursor in step (2) is at least one of zinc oxide, zinc chloride, zinc iodide, zinc bromide and zinc sulfate, and the permanganate in step (3) is at least one of sodium permanganate and potassium permanganate.

[0019] Furthermore, the organic additive is one of urea, ethylenediaminetetraacetic acid (EDTA), N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine, and sodium 2,6-naphthalene disulfonate, and the concentration of the organic additive urea is 0.1 mol L -1 .

[0020] An application of an electrolyte for a long-cycle alkaline zinc-manganese flow battery, and the application of the electrolyte in an alkaline zinc-based flow battery, wherein the alkaline zinc-based flow battery includes an alkaline zinc-manganese flow battery.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The invention is innovative in that urea is used as an additive in the negative electrode electrolyte to react the carbonyl oxygen and amino nitrogen in the urea molecule with Zn 2+ It forms coordination bonds and reconstructs the solvation structure into a [Zn(OH)2(urea)] ternary complex, weakening the interaction between zinc ions and water molecules, promoting three-dimensional uniform diffusion, reducing the nucleation overpotential, inducing the formation of dense small-sized crystal nuclei, and at the same time weakening the "tip effect" on the electrode surface, so that the zinc deposition layer is transformed from coarse dendrites to a honeycomb-like uniform structure, the surface roughness is significantly reduced, the dendrite growth is effectively inhibited, and the life of the zinc-manganese liquid flow battery is improved.

[0023] 2. Urea molecules accumulate on the surface of the zinc sheet through hydrogen bonds to form a dense adsorption layer, blocking direct contact between the zinc sheet and the electrolyte; at the same time, urea forms a hydrogen bond network with water molecules, reducing the free water content, significantly reducing the corrosion current density, and achieving a corrosion inhibition efficiency of 65%, effectively reducing self-corrosion and improving Coulombic efficiency.

[0024] 3. Based on the technical solution of the composite electrolyte, the alkaline zinc-manganese flow battery proposed in the present invention has a high efficiency at 80 mA cm -2 At higher current densities, the cycle life can be increased by 70%, with an average coulombic efficiency of 97.1% and an energy efficiency of 85%. The high-performance electrolyte formed by the additive urea and the active substance sodium tetrahydroxyzincate promotes the reversible kinetics of zinc deposition / dissolution, slowing the growth of interfacial impedance during cycling and reducing the amount of dead zinc shedding, significantly improving the battery's cycle stability and lifespan. Furthermore, the urea molecules prevent direct contact between the zinc sheet and the electrolyte, effectively reducing self-corrosion of the zinc sheet and further improving the battery's coulombic efficiency.

[0025] 4. Finally, urea as an additive is widely available (global annual production exceeds 200 million tons), low-cost (the price is only 1 / 5 of EDTA), non-toxic and harmless, has excellent biodegradability, releases no heavy metals and organic pollutants, and complies with environmental regulations. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the single battery structure and system in the present invention.

[0027] Figure 2 This is a cycle life performance diagram of the zinc-manganese flow battery assembled in Example 1;

[0028] Figure 3 These are the three major efficiency performance diagrams of the zinc-manganese flow battery assembled in Example 1;

[0029] Figure 4 This is a characterization diagram of the negative electrode interface of the zinc-manganese flow battery assembled in Example 1;

[0030] Figure 5 This is a cycle life performance diagram of the zinc-manganese flow battery assembled in Example 2;

[0031] Figure 6 These are the three major efficiency performance diagrams of the zinc-manganese flow battery assembled in Example 2;

[0032] Figure 7 This is a characterization diagram of the negative electrode interface of the zinc-manganese flow battery assembled in Example 2;

[0033] Figure 8 This is a cycle life performance diagram of the zinc-manganese flow battery assembled in Example 3;

[0034] Figure 9 These are the three major efficiency performance diagrams of the zinc-manganese redox flow battery assembled in Example 3;

[0035] Figure 10 This is a characterization diagram of the negative electrode interface of the zinc-manganese flow battery assembled in Example 3;

[0036] Figure 11 Summary diagrams of the cycle life performance and negative electrode interface characterization of zinc-manganese flow batteries assembled with the electrolytes in Example 1, Example 2, and Example 3, respectively. DETAILED DESCRIPTION

[0037] The present invention is described in detail below with reference to specific examples. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the scope of protection of the present invention is not limited to the following examples. Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. All those not described in detail in the following examples can be achieved by conventional experimental means in the art.

[0038] An alkaline zinc-manganese liquid flow battery includes: a positive terminal plate, a positive insulator, a positive electrode (current collector), a positive electrode frame, a gasket, an ion exchange membrane (SPEEK diaphragm), a negative electrode frame, a negative electrode (current collector), a negative insulator, a negative terminal plate, a liquid storage tank, a pipeline, and a pump.

[0039] The positive and negative electrode frames consist of carbon felt, the negative electrode includes a zinc sheet, the positive electrode electrolyte is an alkaline heptavalent manganese solution, and the negative electrode electrolyte is an alkaline zincate solution. SPEEK membrane is used as the ion exchange membrane.

[0040] During charging, the positive and negative electrolytes are pumped from their respective storage tanks to the positive and negative electrodes. The active substance hexavalent manganese in the positive electrolyte loses electrons and undergoes an oxidation reaction to generate hexavalent manganese. The zincate ions in the negative electrode gain electrons and are reduced to zinc elemental form and deposited.

[0041] When charging: MnO4 2- -e - =MnO4 -

[0042] [Zn(OH)4] 2- +2e - =Zn+4OH -

[0043] During discharge, the active substance heptavalent manganese in the positive electrode electrolyte gains electrons and undergoes a reduction reaction to produce hexavalent manganese; the zinc element loses electrons and undergoes an oxidation reaction to produce zincate ions, which are returned to the storage tank through the pump.

[0044] During discharge: MnO4 - +e - =MnO4 2-

[0045] Zn+4OH - -2e - =[Zn(OH)4] 2-

[0046] Since both the positive and negative electrolytes of this battery are alkaline solutions, it overcomes the disadvantage of poor cycling performance caused by different pH values ​​of the electrolytes on both sides of the traditional zinc-manganese flow battery.

[0047] Example 1

[0048] Preparation of positive electrode electrolyte:

[0049] Weigh 60g of sodium hydroxide into a beaker, add an appropriate amount of deionized water, and stir thoroughly with a glass rod to obtain a clear sodium hydroxide solution. After cooling to room temperature, add 8.87g of sodium permanganate solution (40% purity) and adjust the volume to 250ml for later use. The resulting positive electrolyte has a molar concentration of 0.25mol / L of NaMnO4, the active material, and 6mol / L of NaOH, the supporting electrolyte.

[0050] Preparation of negative electrode electrolyte:

[0051] Weigh 60g of sodium hydroxide into a beaker, then add an appropriate amount of deionized water and stir thoroughly with a glass rod to obtain a clear sodium hydroxide solution. After cooling to room temperature, add 2.03g of zinc oxide (99% purity) and adjust the volume to 250ml. The resulting negative electrolyte has a molar concentration of 0.1mol / L of the active material Na2[Zn(OH)]4 and a molar concentration of 6mol / L of the supporting electrolyte NaOH.

[0052] Battery Assembly:

[0053] The assembly of a single cell includes, in sequence, the positive terminal plate, the positive insulator, the positive electrode (current collector), the positive electrode frame (2×2cm 2 Carbon felt), gasket, ion exchange membrane (SPEEK diaphragm), negative electrode frame (2×2cm 2 Carbon felt), zinc sheet, negative electrode (current collector), negative electrode insulator, negative terminal plate. Single cell structure and system see Figure 1 .

[0054] Battery Test:

[0055] The electrolyte flow rate is 20ml / min; the charge and discharge current density is 80mA / cm 2 The charge cutoff voltage is 2.2V, and the discharge cutoff voltage is 1.7V. During deep discharge, the positive electrode Na2MnO4 is further reduced to Na3MnO4, which rapidly decomposes into MnO2, causing blockage of the battery's ducts and composite electrode. Therefore, the lower voltage limit for constant current discharge is set at 1.7V.

[0056] Battery performance see Figure 2 and Figure 3 ,Depend on Figure 2 It can be seen that at a charge and discharge current density of 80mA / cm 2 Under these conditions, the battery will experience voltage instability and reduced potential life due to dendrite growth. Figure 3It can be seen that the imbalance of self-corrosion and hydrogen evolution reactions leads to significant fluctuations and attenuation, which in turn leads to significant fluctuations and attenuation of battery energy efficiency.

[0057] Electrode characterization:

[0058] The surface of the negative electrode carbon felt after battery testing was characterized by scanning electron microscopy (SEM). Figure 4 It can be seen that zinc deposition on the surface of carbon felt is irregular, forming large-area dendrites.

[0059] Example 2

[0060] Preparation of positive electrode electrolyte:

[0061] Weigh 60g of sodium hydroxide into a beaker, add an appropriate amount of deionized water, and stir thoroughly with a glass rod to obtain a clear sodium hydroxide solution. After cooling to room temperature, add 8.87g of sodium permanganate solution (40% purity) and adjust the volume to 250ml. The resulting positive electrolyte has a molar concentration of 0.25mol / L of NaMnO4, the active material, and 6mol / L of NaOH, the supporting electrolyte.

[0062] Preparation of negative electrode electrolyte:

[0063] Weigh 60g of sodium hydroxide into a beaker, add an appropriate amount of deionized water, and stir thoroughly with a glass rod to obtain a clear sodium hydroxide solution. After cooling to room temperature, add 2.03g of zinc oxide (99% purity) and 1.5g of urea, and finally adjust the volume to 250ml for later use. The resulting negative electrolyte has a molar concentration of 0.1mol / L for the active material Na2[Zn(OH)]4, 6mol / L for the supporting electrolyte NaOH, and 0.1mol / L for the additive urea.

[0064] Battery Assembly:

[0065] The single cell includes, in sequence, the positive terminal plate, the positive insulator, the positive electrode (current collector), the positive electrode frame (2×2cm 2 Carbon felt), gasket, ion exchange membrane (SPEEK diaphragm), negative electrode frame (2×2cm 2 carbon felt), zinc sheet, negative electrode (current collector), negative electrode insulator, and negative terminal plate.

[0066] Battery Test:

[0067] The electrolyte flow rate is 20ml / min; the charge and discharge current density is 80mA / cm 2 ;The charging cut-off voltage is 2.2V and the discharging cut-off voltage is 1.7V.

[0068] Battery performance see Figure 5 and Figure 6.Depend on Figure 6 It can be seen that at a charge and discharge current density of 80mA / cm 2 Under these conditions, the battery's energy efficiency reached about 85%, and there was no obvious degradation in performance after 500 cycles.

[0069] Electrode characterization:

[0070] The surface of the negative electrode carbon felt and zinc sheet after battery testing was characterized by scanning electron microscopy (SEM). Figure 7 It can be seen that zinc is uniformly deposited on the surface of the carbon felt without dendrite protrusions.

[0071] Compared with the above embodiment 1, after adding urea to the negative electrolyte in this embodiment, the three major efficiencies of the single cell are more stable in 500 cycles, and the cycle performance does not show obvious attenuation. During the entire cycle, the energy efficiency of the battery reaches 85%. This is because the carbonyl oxygen and amino nitrogen in the urea molecule react with Zn 2+ The formation of coordination bonds reconstructs the solvation structure into a ternary complex of [Zn(OH)2(urea)], weakening the interaction between zinc ions and water molecules, promoting three-dimensional uniform diffusion, reducing the nucleation overpotential, and inducing the formation of dense small-sized nuclei. Simultaneously, it weakens the "tip effect" on the electrode surface, transforming the zinc deposit from coarse dendrites to a uniform structure, significantly reducing surface roughness and effectively inhibiting dendrite growth. This effectively inhibits dendrite growth and extends the life of zinc-manganese flow batteries.

[0072] Example 3

[0073] In this embodiment, the negative electrode electrolyte contains only the supporting electrolyte sodium hydroxide, does not contain the active material Na2[Zn(OH)]4, and does not contain urea.

[0074] Preparation of positive electrode electrolyte:

[0075] Weigh 60g of sodium hydroxide into a beaker, add an appropriate amount of deionized water, and stir thoroughly with a glass rod to obtain a clear sodium hydroxide solution. After cooling to room temperature, add 8.87g of sodium permanganate solution (40% purity) and adjust the volume to 250ml for later use. The resulting positive electrolyte has a molar concentration of 0.25mol / L of NaMnO4, the active material, and 6mol / L of NaOH, the supporting electrolyte.

[0076] Preparation of negative electrode electrolyte:

[0077] Weigh 60g of sodium hydroxide into a beaker, then add an appropriate amount of deionized water. Stir thoroughly with a glass rod to obtain a clear sodium hydroxide solution. After cooling to room temperature, dilute to 250ml for later use. The resulting negative electrode electrolyte solution has a supporting electrolyte NaOH concentration of 6 mol / L.

[0078] Battery Assembly:

[0079] The assembly of a single cell includes, in sequence, the positive terminal plate, the positive insulator, the positive electrode (current collector), the positive electrode frame (2×2cm 2 Carbon felt), gasket, ion exchange membrane (SPEEK diaphragm), negative electrode frame (2×2cm 2 Carbon felt), zinc sheet, negative electrode (current collector), negative electrode insulator, negative terminal plate. Single cell structure and system see Figure 1 .

[0080] Battery Test:

[0081] The electrolyte flow rate is 20ml / min; the charge and discharge current density is 80mA / cm 2 ;The charging cut-off voltage is 2.2V and the discharging cut-off voltage is 1.7V.

[0082] Depend on Figure 8 It can be seen that at a charge and discharge current density of 80mA / cm 2 Under these conditions, the battery's cycle performance only lasted for 45 hours. Figure 9 It can be seen that the stability of the three major efficiencies of the battery deteriorates after 300 charge and discharge cycles. This is because the negative electrode electrolyte in this embodiment only contains the supporting electrolyte sodium hydroxide and no active material, and the zinc ions come from the dissolution of the zinc flakes, which results in uneven concentration distribution of zinc ions in the electrolyte, resulting in uneven deposition of zinc ions. Due to the lack of active material as a stable form of zinc ions, the utilization rate of zinc is reduced, the discharge capacity of the battery is reduced, and the deposition efficiency of zinc during charging is also reduced. The cycle life of the battery is significantly reduced, and compared with Example 1, it is only 45 hours. Moreover, when the battery is charging, zinc grows in the form of dendrites; after the battery is discharged, the zinc dendrites are not completely dissolved. Due to the small specific surface area of ​​the zinc flakes, the local current density is large, which is not conducive to the dissolution of zinc dendrites. Moreover, after the battery in this embodiment has been cycled for a long time, "dead zinc" will be deposited in the negative electrode electrolyte. The dead zinc cannot participate in the electrochemical reaction of the battery, which will lead to capacity loss of the battery.

[0083] In Example 1, the negative electrolyte contains the active substance sodium zincate, which acts as a medium for zinc dissolution and deposition. During discharge, the zinc flakes dissolve into the electrolyte, forming sodium zincate. During charging, the zinc ions in the sodium zincate are reduced and deposited on the zinc flakes. Therefore, the presence of the electrolyte ensures a more complete reversible reaction of zinc, thereby improving the battery's capacity utilization.

[0084] Depend on Figure 9As can be seen, the increased voltage fluctuation in this example is due to the lack of the active substance sodium tetrahydroxyzincate in the negative electrode electrolyte. The redox reaction of zinc may be restricted by the electrolyte composition, resulting in increased voltage fluctuation. During discharge, the battery voltage drops more rapidly, while during charging, the voltage may rise or fluctuate abnormally, affecting the overall performance of the battery.

[0085] Electrode characterization:

[0086] The surface of the negative electrode carbon felt after battery testing was characterized by scanning electron microscopy (SEM). Figure 10 It can be seen that zinc deposition on the surface of carbon felt is irregular, forming large-area irregular dendrites.

[0087] Examples 4-6

[0088] This example refers to the preparation method of Example 2, and the negative electrode electrolyte and positive electrode electrolyte of the battery are prepared respectively. The same battery is assembled and the same test is carried out. The difference is that the organic additives in the negative electrode electrolyte are different, as shown in Table 1 below. Table 1

[0089]

[0090] Example 4

[0091] An electrochemical test of an electrolyte for a long-cycle alkaline zinc-manganese flow battery comprises the following steps:

[0092] The pretreated zinc alloy electrode was placed in the electrolytes of Examples 1, 2, and 3 above. The open circuit potential was first tested for 1800 s to stabilize the electrode potential, and then Tafel curve test and EIS test were performed.

[0093] Corrosion inhibition efficiency (η i %) is calculated according to the following formula:

[0094]

[0095] Among them, i corr and i corr(inh) Corrosion current density of zinc alloy without and with composite additives.

[0096] The polarization curve fitting parameters of the zinc alloy electrode in the negative electrolyte of Example 1, the negative electrolyte containing urea as an additive in Example 2, and the blank electrolyte of Example 3 are shown in Table 2. The negative electrolyte of Example 3 can be regarded as Blank.

[0097] Table 2

[0098]

[0099] As can be seen from Table 1, the corrosion inhibition efficiency of Example 1 is 28.69% relative to that of Example 3, and the corrosion inhibition efficiency of Example 2 is 65.98% relative to that of Example 3. This shows that when urea is added to the negative electrode electrolyte as an additive, urea and the active substance sodium tetrahydroxyzincate exert a synergistic effect, and its corrosion inhibition effect on the negative electrode zinc sheet is optimal.

Claims

1. A long-cycle alkaline zinc-manganese flow battery electrolyte, comprising a negative electrode electrolyte and a positive electrode electrolyte, characterized in that: The negative electrode electrolyte includes a complex solution formed by mixing a zinc precursor, an organic additive and a strong base, wherein the organic additive includes one of urea, ethylenediaminetetraacetic acid (EDTA), N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine, and sodium 2,6-naphthalene disulfonate, and the zinc precursor is dissolved in the strong base to generate Zn(OH)4 2- The positive electrode electrolyte includes a mixed solution formed by mixing permanganate and a strong base.

2. The electrolyte according to claim 1, characterized in that The zinc precursor in the negative electrode electrolyte is at least one of zinc oxide, zinc chloride, zinc iodide, zinc bromide and zinc sulfate.

3. The electrolyte according to claim 1, characterized in that In the positive electrode electrolyte, the permanganate is at least one of sodium permanganate and potassium permanganate.

4. The electrolyte according to claim 1, characterized in that The strong base in the negative electrode electrolyte and the positive electrode electrolyte is at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide.

5. The electrolyte according to claim 1, characterized in that The zinc precursor is dissolved in a strong base to generate Zn(OH)4 2- The molar concentration of the organic additive is 0.1 to 1 mol / L, and the molar concentration of the strong base is 6 mol / L.

6. A method for preparing an electrolyte for a long-cycle alkaline zinc-manganese flow battery according to any one of claims 1 to 5, characterized in that: The following steps are included: (1) Prepare two strong alkaline solutions as supporting electrolyte solutions for the negative electrode electrolyte and the positive electrode electrolyte, respectively, and then cool them to room temperature for later use; (2) Add zinc precursor to one of the strong base solutions, and mix the zinc precursor and the strong base evenly under water bath heating and magnetic stirring to obtain a solution containing the active substance Zn(OH)4 2- The solution was cooled to room temperature for later use; (3) Add the organic additive to step (2) and stir until it is completely dissolved to obtain a mixture containing the organic additive and the active substance Zn(OH)4 2- Compound negative electrode electrolyte, (4) Add permanganate to another strong base solution and wait for it to cool to room temperature to obtain a solution containing the active substance MnO 4- of the positive electrode electrolyte.

7. The method for preparing an electrolyte for a long-cycle alkaline zinc-manganese flow battery according to claim 6, wherein: In the step (1), OH in the strong alkaline solution in the negative electrode electrolyte and the positive electrode electrolyte - The concentration of the active substance Zn(OH)4 in step (2) is 6 mol / L. 2- The concentration is 0.1-1 mol L -1 ; The active material MnO in step (3) 4- The concentration is 0.1-1 mol L -1 8. The method for preparing an electrolyte for a long-cycle alkaline zinc-manganese flow battery according to claim 6, wherein: The strong base is one of sodium hydroxide, potassium hydroxide and lithium hydroxide, the zinc precursor in step (2) is at least one of zinc oxide, zinc chloride, zinc iodide, zinc bromide and zinc sulfate, and the permanganate in step (3) is at least one of sodium permanganate and potassium permanganate.

9. The method for preparing an electrolyte for a long-cycle alkaline zinc-manganese flow battery according to claim 6, wherein: The organic additive is one of urea, ethylenediaminetetraacetic acid (EDTA), N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine, and sodium 2,6-naphthalene disulfonate. The concentration of the organic additive urea is 0.1 mol L -1 .

10. Use of the electrolyte according to claim 1, wherein the electrolyte is used in an alkaline zinc-based flow battery, wherein the alkaline zinc-based flow battery includes an alkaline zinc-manganese flow battery.

Images