Zinc-iodine flow battery negative electrode electrolyte and zinc-iodine flow battery

Abstract

The invention relates to a zinc-iodine flow battery negative electrode electrolyte and a zinc-iodine flow battery thereof. The negative electrode electrolyte comprises a zinc salt, a supporting electrolyte and an additive, the additive comprises glucosamine sulfate, and the concentration of the additive is 0.01-0.3 mol / L; the concentration of the zinc salt is 0.1 to 6 mol / L, and the concentration of the supporting electrolyte is 0.1 to 3 mol / L. The introduced additive is low in cost and good in biological safety, compared with water molecules, the additive is preferentially adsorbed on the surface of zinc and can be intercalated with a solvation sheath layer of Zn < 2 + >, corrosion and hydrogen evolution of a zinc negative electrode are effectively inhibited, the dynamic characteristics of zinc ions are strengthened, the flux of the zinc ions is homogenized, Zn < 2 + > / Zn (002) crystal face directional deposition is promoted, the stability of negative electrode reaction is greatly improved, and the service life of the negative electrode is prolonged. The service life of the battery is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid flow batteries and relates to a negative electrode electrolyte of a zinc-iodine liquid flow battery, in particular to a negative electrode electrolyte of a zinc-iodine liquid flow battery. Background Art

[0002] The overconsumption of fossil fuels and the resulting environmental problems have exacerbated the global energy crisis. Given the discontinuous, unstable, and uncontrollable nature of renewable energy generation, such as wind, solar, and wave power, the development of high-energy-density, low-cost, safe, and reliable large-scale energy storage systems is crucial for driving global energy transformation and achieving sustainable development goals. Flow batteries offer significant advantages, including long life, high safety, a high degree of decoupling between energy and power, and scalability. Typical flow battery systems, such as all-vanadium and zinc-iron, have low energy densities due to limited solubility. Zinc-iodine flow batteries, however, have high solubility of their active materials and operate in neutral or weakly acidic environments, offering promising application prospects.

[0003] During the operation of zinc-iodine flow batteries, the negative electrode side often faces problems such as zinc corrosion, hydrogen evolution, and the formation and shedding of zinc dendrites, which in turn cause irreversible capacity decay and seriously affect the stability and service life of the battery cycle. Therefore, regulating the directional and orderly deposition of zinc ions through electrode modification, diaphragm modification, and electrolyte engineering is of great significance for the practical application of zinc-iodine flow batteries, protecting the zinc negative electrode and improving stability. Among them, electrolyte engineering introduces additives containing functional groups to control reaction kinetics, which is a simple and cost-effective strategy. Summary of the Invention

[0004] In response to the above-mentioned defects of the prior art, the task of the present invention is to provide a zinc-iodine liquid flow battery negative electrode electrolyte that can effectively inhibit negative electrode zinc dendrites, corrosion and hydrogen evolution, regulate the negative electrode reaction kinetics characteristics, and solve the problems of rapid loss of negative electrode active material, severe capacity decay, and short cycle life of zinc-iodine liquid flow batteries.

[0005] The technical solutions of the present invention are as follows:

[0006] A zinc-iodine flow battery negative electrode electrolyte comprises a solvent, a zinc salt, a supporting electrolyte and an additive, wherein the additive is glucosamine sulfate, and the concentration of the additive is 0.01 to 0.3 mol / L; the concentration of the zinc salt is 0.1 to 6 mol / L, and the concentration of the supporting electrolyte is 0.1 to 3 mol / L.

[0007] Preferably, the solvent is deionized water.

[0008] Preferably, the zinc salt is any one of zinc bromide, zinc chloride, zinc iodide, zinc sulfate or zinc acetate.

[0009] Preferably, the zinc salt is zinc bromide.

[0010] Preferably, the supporting electrolyte is any one of lithium chloride, lithium bromide, lithium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide or potassium iodide, or a combination of at least two of them, which is used to improve the conductivity of the electrolyte and alleviate the Zn 2+ The volume change of the electrolyte at both electrodes as the carriers migrate.

[0011] Preferably, the supporting electrolyte is potassium chloride.

[0012] Furthermore, the concentration of the zinc salt is 0.1 to 6 mol / L, the concentration of the supporting electrolyte is 0.1 to 3 mol / L, and the concentration of the additive is 0.01 to 0.3 mol / L.

[0013] Preferably, the concentration of the zinc salt is 1 to 3 mol / L, the concentration of the supporting electrolyte is 1 to 2 mol / L, and the concentration of the additive is 0.02 to 0.1 mol / L.

[0014] As further preferred, the concentration of the zinc salt is 2 mol / L, the concentration of the supporting electrolyte is 2 mol / L, and the concentration of the additive is 0.05 mol / L.

[0015] On the other hand, the present invention provides a zinc-iodine liquid flow battery using the negative electrode electrolyte. The positive and negative electrodes of the zinc-iodine liquid flow battery reactor are graphite felt, the diaphragm is a cation exchange membrane, the negative electrode electrolyte is the zinc-iodine liquid flow battery negative electrode electrolyte, and the positive electrode electrolyte is iodine salt and supporting electrolyte.

[0016] Furthermore, the graphite felt is heat-treated, and the cation exchange membrane is any one of a Nafion membrane and a SPEEK membrane.

[0017] Preferably, the thickness of the graphite felt is 2-4 mm, and the cation exchange membrane is Nafion 115.

[0018] As a further preference, the thickness of the graphite felt is 2.5 mm.

[0019] Furthermore, the iodine salt in the positive electrode electrolyte is any one of zinc iodide, potassium iodide, and sodium iodide, or a combination of at least two of them. The concentration of iodine ions in the positive electrode electrolyte is twice the concentration of zinc ions in the negative electrode electrolyte. The supporting electrolyte in the positive electrode electrolyte is the same as the supporting electrolyte in the negative electrode electrolyte.

[0020] Preferably, the iodized salt is potassium iodide.

[0021] As a further preference, the negative electrode electrolyte is added with an iodine salt in an amount equal to that of the positive electrode electrolyte, and the positive electrode electrolyte is added with a zinc salt in an amount equal to that of the negative electrode electrolyte.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention uses glucosamine sulfate as a zinc negative electrode electrolyte additive. The additive has low cost and good biosafety. It contains hydroxyl and amino functional groups. Compared with water molecules, it is preferentially adsorbed on the surface of zinc, reducing interfacial active water and inhibiting side reactions such as corrosion and hydrogen evolution. During the zinc deposition process, the positively charged amino groups are adsorbed on the surface of zinc, which can reduce the interfacial charge transfer impedance, induce uniform zinc flux, accelerate the zinc diffusion rate and promote Zn 2+ / Zn(002) crystal plane directional deposition avoids the generation of zinc dendrites and local electric field disorder, and improves the stability of the negative electrode electrolyte.

[0024] (2) The zinc-iodine flow battery designed in the present invention uses glucosamine sulfate as a negative electrode electrolyte additive, which can effectively regulate the deposition of zinc, inhibit the corrosion of the zinc negative electrode, improve the cycle reversibility, play a positive role in stabilizing the zinc negative electrode, and significantly improve the cycle life of the zinc-iodine flow battery, and has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It does not contain glucosamine sulfate and contains 0.05 mol L -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 ) The corresponding zinc-iodine flow battery at 40 mA cm -2 , 15mAh cm -2 Cycling performance (volumetric capacity and coulombic efficiency) curves under charge and discharge conditions.

[0026] Figure 2 No glucosamine sulfate and 0.02, 0.05, 0.1, 0.2 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 mol L -1 ) The corresponding zinc-iodine flow battery at 40 mA cm -2 , 15mAh cm -2 Schematic diagram comparing the average Coulombic efficiency of the first 10 cycles, first 20 cycles, first 30 cycles and first 40 cycles under charge and discharge conditions.

[0027] Figure 3 Containing 0.05 mol L -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 2 mol L -1 ) The corresponding zinc-iodine flow battery at 40mAcm -2, 30mAh cm -2 Cycling performance (volumetric capacity and coulombic efficiency) curves under charge and discharge conditions.

[0028] Figure 4 It does not contain glucosamine sulfate and contains 0.05 mol L -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 ) The corresponding zinc-zinc flow battery at 40mAcm -2 , 10mAh cm -2 Cyclic voltage curve under charge and discharge conditions.

[0029] Figure 5 It does not contain glucosamine sulfate and contains 0.05 mol L -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 ) The corresponding zinc-zinc flow battery at 40mAcm -2 , 10mAh cm -2 Cycling performance (Coulomb efficiency) curve under charge and discharge conditions.

[0030] Figure 6 Does not contain glucosamine sulfate and contains 0.05 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 ), at 5mAcm -2 In-situ optical microscopy images of zinc deposition after charging at current densities of 0, 30, 60, and 90 minutes.

[0031] Figure 7 Does not contain glucosamine sulfate and contains 0.05 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 ), at 5mAcm -2 X-ray diffraction pattern of the zinc sheet electrode after charging for 90 minutes at the same current density.

[0032] Figure 8 Does not contain glucosamine sulfate and contains 0.05 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 ), at 5mAcm -2 Scanning electron microscope image of the zinc sheet electrode after charging for 90 minutes at the same current density.

[0033] Figure 9 It does not contain glucosamine sulfate and contains 0.05 mol L -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 )'s chronoamperometric curve spectrum.

[0034] Figure 10 Does not contain glucosamine sulfate and contains 0.05 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 )'s AC impedance curve.

[0035] Figure 11 No glucosamine sulfate and 0.05, 0.1, 0.2 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 mol L -1 ) Contact angle test image with zinc sheet.

[0036] Figure 12 Infrared spectra of zinc flakes, zinc flakes soaked in saturated glucosamine sulfate solution for 24 hours, and glucosamine sulfate powder.

[0037] Figure 13 Does not contain glucosamine sulfate and contains 0.05 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 )Linear voltammetric scan curve.

[0038] Figure 14 Does not contain glucosamine sulfate and contains 0.05 molL -1 Glucosamine sulfate negative electrolyte (zinc ion concentration 1 molL -1 )'s Tafel curve spectrum. DETAILED DESCRIPTION

[0039] The present application is described in detail below with reference to comparative examples and embodiments, but the present application is not limited to these comparative examples and embodiments.

[0040] Unless otherwise specified, the raw materials in the comparative examples and examples of this application were purchased through commercial channels.

[0041] Zinc-iodine (Zn||I) flow battery assembly: Gold-plated copper plates serve as current collectors, bipolar plates use highly conductive graphite plates, positive and negative electrodes are heat-treated porous graphite felt with a thickness of 2.5 mm, and the separator is an activated cation exchange membrane Nafion 115.

[0042] Test conditions for zinc-iodine flow battery: battery effective area is 16cm 2 (4*4cm 2 ), the battery was tested with constant current charge and discharge on the Blue Electric test platform CT3002K, with a charge and discharge current density of 40 mA cm -2 The charging cut-off condition is that the charging capacity reaches 240mAh (15mAh cm -2 ) or the voltage reaches 1.6V, and the discharge cut-off condition is when the voltage drops to 0.1V.

[0043] Zinc-zinc (Zn||Zn) flow battery assembly: Highly conductive graphite plates serve as current collectors and bipolar plates. The negative electrode is a heat-treated porous graphite felt with a thickness of 4.35 mm. The positive electrode is a heat-treated porous graphite felt and a zinc foil composite with thicknesses of 4.35 mm and 0.2 mm, respectively. The separator is an activated cation exchange membrane Nafion 115.

[0044] Test conditions for zinc flow battery: the battery active area is 13.5cm 2 (3*4.5cm 2 ), the battery was tested with constant current charge and discharge on the Blue Electric test platform CT3002K, with a charge and discharge current density of 40mAcm -2 The charging cut-off condition is that the charging capacity reaches 135mAh (10mAh cm -2 ), the discharge cut-off condition is when the voltage drops to -0.5V.

[0045] Comparative Example 1 and Examples 1 to 5 are zinc-iodine (Zn||I) flow battery tests, and Comparative Example 2 and Example 6 are zinc-zinc (Zn||Zn) flow battery tests. 2+ The concentration of active substances and the concentration of glucosamine sulfate added to the negative electrode electrolyte are shown in the following table:

[0046] Comparative Examples and Examples <![CDATA[Active substance concentration (Zn 2+ )]]> Addition concentration of glucosamine sulfate in the negative electrode electrolyte Comparative Example 1 (Zn||I) <![CDATA[1mol L -1 ]]> <![CDATA[0mol L -1 ]]> Example 1 (Zn||I) <![CDATA[1mol L -1 ]]> <![CDATA[0.02mol L -1 ]]> Example 2 (Zn||I) <![CDATA[1mol L -1 ]]> <![CDATA[0.05mol L -1 ]]> Example 3 (Zn||I) <![CDATA[1mol L -1 ]]> <![CDATA[0.1mol L -1 ]]> Example 4 (Zn||I) <![CDATA[1mol L -1 ]]> <![CDATA[0.2mol L -1 ]]> Example 5 (Zn||I) <![CDATA[2mol L -1 ]]> <![CDATA[0.05mol L -1 ]]> Comparative Example 2 (Zn||Zn) <![CDATA[1mol L -1 ]]> <![CDATA[0mol L -1 ]]> Example 6 (Zn||Zn) <![CDATA[1mol L -1 ]]> <![CDATA[0.05mol L -1 ]]>

[0047] Comparative Example 1

[0048] A zinc-iodine flow battery without additives was used as comparative example 1, and the compositions of the positive and negative electrolytes were both 10 mL of 1 mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl. The cell's effective area is 16 cm 2 , the charge and discharge current density is 40mAcm -2 The charging cut-off condition is that the charging capacity reaches 240mAh (15mAh cm -2 ) or the voltage reaches 1.6V, and the discharge cut-off condition is when the voltage drops to 0.1V. Figure 1 The cycle performance curve of comparative example 1 shows that after 40 cycles, the irreversible capacity decay caused by dendrites, corrosion and other problems leads to a sharp drop in battery efficiency and a short cycle life. Figure 2 As shown, the average coulombic efficiency of comparative example 1 in the first 30 cycles is 99.5%, and the average coulombic efficiency in the first 40 cycles is lower than 99.4% due to serious side reactions, so it cannot be used in large-scale practical applications.

[0049] Examples 1 to 4

[0050] The assembly of the zinc-iodine flow batteries in Examples 1 to 4 was the same as that in Comparative Example 1, the test conditions were the same as those in Comparative Example 1, and the positive electrode electrolyte was the same as that in Comparative Example 1. The difference was the composition of the negative electrode electrolyte, in which different concentrations of glucosamine sulfate were added.

[0051] Example 1

[0052] For zinc-iodine flow batteries with additives added to the negative electrolyte, the composition of the negative electrolyte is 10 mL of 1 mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl, 0.02 mol L -1 Glucosamine sulfate, the positive electrolyte composition is 10mL of 1mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl. The cell's effective area is 16 cm 2 , the charge and discharge current density is 40mAcm -2 The charging cut-off condition is that the charging capacity reaches 240mAh (15mAh cm -2 ) or the voltage reaches 1.6V, the discharge cut-off condition is when the voltage drops to 0.1V. Figure 2 As shown, 0.02 mol L -1 The average coulombic efficiency of the zinc-iodine flow battery after glucosamine sulfate addition in the first forty cycles was 99.55%, and there was no rapid capacity decay, indicating that glucosamine sulfate helps to enhance battery performance and improve operational stability.

[0053] Example 2

[0054] For zinc-iodine flow batteries with additives added to the negative electrolyte, the composition of the negative electrolyte is 10 mL of 1 mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl, 0.05 mol L -1 Glucosamine sulfate, the positive electrolyte is 10mL of 1mol L - 1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl. The cell's effective area is 16 cm 2 , the charge and discharge current density is 40mAcm -2 The charging cut-off condition is that the charging capacity reaches 240mAh (15mAh cm -2) or the voltage reaches 1.6V, the discharge cut-off condition is when the voltage drops to 0.1V. Figure 2 As shown, 0.05 mol L -1 The average coulombic efficiency of the zinc iodine flow battery after the addition of glucosamine sulfate in the first forty cycles was 99.64%, and the performance of the battery was significantly improved. Figure 1 The long cycle test in the experiment showed that the -1 The zinc-iodine flow battery based on glucosamine sulfate showed no significant efficiency degradation after 240 cycles.

[0055] Example 3

[0056] For zinc-iodine flow batteries with additives added to the negative electrolyte, the composition of the negative electrolyte is 10 mL of 1 mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl, 0.1 mol L -1 Glucosamine sulfate, the positive electrolyte is 10mL of 1mol L - 1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl. The cell's effective area is 16 cm 2 , the charge and discharge current density is 40 mA cm -2 The charging cut-off condition is that the charging capacity reaches 240mAh (15mAh cm -2 ) or the voltage reaches 1.6V, the discharge cut-off condition is when the voltage drops to 0.1V. Figure 2 As shown, add 0.1 molL -1 The average coulombic efficiency of the zinc-iodine flow battery after glucosamine sulfate addition in the first forty cycles was 99.54%, and no rapid capacity decay occurred, indicating that glucosamine sulfate helps to enhance the performance of the battery and improve the stability of operation.

[0057] Example 4

[0058] For zinc-iodine flow batteries with additives added to the negative electrolyte, the composition of the negative electrolyte is 10 mL of 1 mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl, 0.2 mol L -1 Glucosamine sulfate, the positive electrolyte is 10mL of 1mol L - 1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl. The cell's effective area is 16 cm2 , the charge and discharge current density is 40 mA cm -2 The charging cut-off condition is that the charging capacity reaches 240mAh (15mAh cm -2 ) or the voltage reaches 1.6V, the discharge cut-off condition is when the voltage drops to 0.1V. Figure 2 As shown, add 0.2 molL -1 The average coulombic efficiency of the zinc-iodine flow battery in the first forty cycles after the addition of glucosamine sulfate was 99.42%, showing a trend of slow decay. This was because the increase in the concentration of glucosamine sulfate led to an increase in the viscosity of the electrolyte, which affected the negative electrode reaction kinetics. Therefore, the average coulombic efficiency of the zinc-iodine flow battery cycle did not increase significantly.

[0059] Example 5

[0060] In Example 5, the concentration of the active material at both poles of the zinc-iodine flow battery was increased by 2 times compared with that in Comparative Example 1. The concentration of glucosamine sulfate added was the same as that in Example 2. The assembly was the same as that in Comparative Example 1. The test conditions were the same as those in Comparative Example 1 except for the charge cut-off condition. For the zinc-iodine flow battery with the additive added to the negative electrolyte, the negative electrolyte was 10 mL of 2 mol L -1 ZnBr2, 4 mol L -1 KI, 2 mol L -1 KCl, 0.05 mol L -1 Glucosamine sulfate, the positive electrolyte is 10mL of 2mol L -1 ZnBr2, 4 mol L -1 KI, 2 mol L -1 KCl. The cell's effective area is 16 cm 2 , the charge and discharge current density is 40mAcm -2 The charging cut-off condition is that the charging capacity reaches 480mAh (30mAh cm -2 ) or the voltage reaches 1.6V, the discharge cut-off condition is when the voltage drops to 0.1V. Figure 3 As shown, the addition of 0.05 mol L -1 Long cycle performance of zinc iodine flow battery after glucosamine sulfate, the battery can be used at 40mAcm -2 , 30mAh cm -2 Under the same conditions, it can continuously and stably operate for 500 charge and discharge cycles without obvious capacity and coulombic efficiency attenuation. The average coulombic efficiency of 500 cycles reaches 99.61%, which has good practical application prospects.

[0061] Comparative Example 2

[0062] In order to avoid the influence of the loss of cathode iodine active material during the reaction, the effectiveness of glucosamine sulfate on the regulation of zinc anode was investigated by assembling a zinc-zinc flow battery. A zinc-zinc flow battery without additives was used as comparative example 2. The composition of the positive and negative electrolytes was 15mL of 1mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl. The cell's active area is 13.5 cm 2 , the charge and discharge current density is 40mAcm -2 The charging cut-off condition is that the charging capacity reaches 135mAh (10mAh cm -2 ), the discharge cut-off condition is when the voltage drops to -0.5V. Figure 4 The cyclic voltage curve of comparative example 2 shows that the voltage at 100h is severely polarized, corresponding to Figure 5 The Coulombic efficiency shown in the figure decays sharply, indicating that serious irreversible side reactions have occurred.

[0063] Example 6

[0064] For zinc flow batteries with additives added to the negative electrolyte, the composition of the negative electrolyte is 15mL of 1molL -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl, 0.05 mol L -1 Glucosamine sulfate, the positive electrolyte composition is 15mL of 1mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl. The cell's active area is 13.5 cm 2 , the charge and discharge current density is 40mAcm -2 The charging cut-off condition is that the charging capacity reaches 135mAh (10mAh cm -2 ), the discharge cut-off condition is when the voltage drops to -0.5V. Figure 4 As shown, 0.05 mol L -1 The zinc flow battery after glucosamine sulfate can be stably cycled for more than 500 hours without experiencing sharp voltage polarization. Figure 5 Shows the addition of 0.05 mol L -1 The Zn-Zn flow battery exhibited good coulombic efficiency stability after glucosamine sulfate addition, indicating that glucosamine sulfate was effective in suppressing side reactions and stabilizing the Zn anode.

[0065] Example 7

[0066] For the negative electrode electrolyte of zinc-iodine flow battery with or without glucosamine sulfate, the regulating effect of glucosamine sulfate on zinc deposition was investigated. 3 The zinc deposition experiment was carried out in a cuvette with a positive and negative electrode of 2*2cm 2 The distance between the positive and negative electrodes is 2 cm, and the electrolyte is filled with 8 mL of 1 mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl and 8 mL of 1 mol L -1 ZnBr2, 2 mol L -1 KI + 2 mol L -1 KCl, 0.05 mol L -1 Glucosamine sulfate, corresponding to the negative electrode electrolyte composition of the zinc iodine flow battery of Example 1 and Example 2, respectively. -2 The zinc deposition process was photographed in situ using an optical microscope. Figure 6 As shown in the figure, the zinc deposit containing glucosamine sulfate has a denser morphology and a smaller deposit thickness, which is beneficial to improving the reversibility of the reaction and matching the high surface capacity operating conditions. The negative electrode was taken out for analysis and testing, such as Figure 7 As shown, X-ray diffraction analysis (XRD) showed that compared with the control condition without glucosamine sulfate, the -1 In the case of glucosamine sulfate, the intensity ratio of Zn(002) / Zn(100) increased from 2.95 to 5.05, indicating that glucosamine sulfate promoted the 2+ / Zn(002) crystal plane directional deposition, corresponding to Figure 8 The scanning electron microscope spectrum shows that 0.05 mol L -1 In the case of glucosamine sulfate, the zinc deposition layer is smooth and has a 002 crystal structure, the growth of zinc dendrites is suppressed, and the stability of the reaction process is significantly improved. The diffusion pattern of zinc deposition in the negative electrolyte of the zinc-iodine flow battery containing or not containing glucosamine sulfate was analyzed by chronoamperometry. A three-electrode test method was adopted, with a glassy carbon electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. Figure 9 As shown in the figure, with the increase of deposition time, the current corresponding to the negative electrode electrolyte containing glucosamine sulfate tends to stabilize faster, while the current corresponding to the negative electrode electrolyte without glucosamine sulfate continues to increase, indicating that glucosamine sulfate can make the zinc diffusion mode enter 3D diffusion faster, promote the uniform deposition of zinc and inhibit dendrites.

[0067] Example 8

[0068] The enhancement effect of glucosamine sulfate on the zinc anode reaction kinetics was investigated for zinc iodine flow battery negative electrode electrolytes containing and not containing glucosamine sulfate. The electrolytes used in the tests were 1 mol L -1 ZnBr2, 2 mol L -1 KI, 2 mol L -1 KCl and 1 mol L -1 ZnBr2, 2 mol L -1 KI + 2 mol L -1 KCl, 0.05 mol L -1 Glucosamine sulfate, corresponding to the negative electrode electrolyte composition of the zinc iodine flow battery in Example 1 and Example 2, respectively. The AC impedance test was performed using a three-electrode test method, with a glassy carbon electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. The test frequency range was 0.01 Hz to 100 kHz. Figure 10 In the impedance spectrum shown, the arc radius in the high-frequency region decreases and the slope of the straight line in the low-frequency region increases, indicating that glucosamine sulfate reduces the charge transfer impedance at the electrolyte / electrode interface and promotes the diffusion performance of zinc ions.

[0069] Example 9

[0070] The adsorption of glucosamine sulfate on the zinc anode was investigated for the negative electrode electrolyte of zinc-iodine flow batteries containing or not containing glucosamine sulfate. The zinc affinity of glucosamine sulfate was analyzed by measuring the contact angle between the electrolyte and the zinc sheet. The electrolyte used in the test was 1 mol L -1 ZnBr2, 2molL -1 KI, 2molL -1 On this basis, 0.05, 0.1, and 0.2 mol L KCl were added, respectively. -1 The negative electrolyte of glucosamine sulfate, such as Figure 11 As shown in the figure, as the concentration of glucosamine sulfate increases, the contact angle between the electrolyte and the zinc sheet decreases, indicating that glucosamine sulfate has a strong affinity for zinc and is preferentially adsorbed on the surface of the zinc sheet. The adsorption between glucosamine sulfate and zinc sheet was analyzed by infrared spectroscopy, as shown in the figure. Figure 12 As shown, the zinc sheet after being immersed in a saturated glucosamine sulfate solution for 24 hours showed obvious glucosamine sulfate absorption band characteristics, indicating that glucosamine sulfate can be spontaneously adsorbed on the surface of the zinc sheet, reflecting the strong adsorption effect between glucosamine sulfate and the zinc sheet.

[0071] Example 10

[0072] The interfacial protection effect of glucosamine sulfate on the zinc anode was investigated for the negative electrode electrolyte of zinc iodine flow battery with or without glucosamine sulfate. The electrolytes used in the tests were 1 mol L -1 ZnBr2, 2 mol L-1 KI, 2 mol L -1 KCl and 1 mol L -1 ZnBr2, 2 mol L -1 KI + 2 mol L -1 KCl, 0.05 mol L -1 Glucosamine sulfate, corresponding to the negative electrode electrolyte composition of the zinc iodine flow battery in Example 1 and Example 2, respectively. A linear voltammetric sweep test was performed using a three-electrode test method, with a glassy carbon electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the counter electrode, at a sweep rate of 2 mV s -1 .like Figure 13 As shown in the figure, the negative electrolyte containing glucosamine sulfate has a more negative hydrogen evolution potential, indicating that glucosamine sulfate can inhibit the hydrogen evolution side reaction and improve the anode stability. The Tafel test was carried out using a three-electrode test method, with a zinc sheet electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. Figure 14 As shown in the figure, after adding glucosamine sulfate, the corrosion current of the negative electrode electrolyte increased from 8.497 mA cm -2 Reduced to 4.503 mA cm -2 , indicating that glucosamine sulfate helps to improve the corrosion resistance of zinc anode.

[0073] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical personnel familiar with the profession, without departing from the scope of the technical solution of this application, any technical solution formed by equivalent replacement or equivalent transformation of the technical content disclosed above shall fall within the scope of protection of the claims attached to the present invention.

Claims

1. A zinc-iodine flow battery negative electrode electrolyte, characterized in that The invention comprises a solvent, a zinc salt, a supporting electrolyte and an additive, wherein the additive is glucosamine sulfate, and the concentration of the additive is 0.01-0.3 mol / L; the concentration of the zinc salt is 0.1-6 mol / L, and the concentration of the supporting electrolyte is 0.1-3 mol / L.

2. The zinc-iodine flow battery negative electrode electrolyte according to claim 1, characterized in that The concentration of the zinc salt is 1-3 mol / L, the concentration of the supporting electrolyte is 1-2 mol / L, and the concentration of the additive is 0.02-0.1 mol / L.

3. The negative electrode electrolyte of the zinc-iodine flow battery according to claim 2, characterized in that The concentration of the zinc salt is 2 mol / L, the concentration of the supporting electrolyte is 2 mol / L, and the concentration of the additive is 0.05 mol / L.

4. The zinc-iodine flow battery negative electrode electrolyte according to claim 1, characterized in that The solvent is deionized water; the zinc salt is any one of zinc bromide, zinc chloride, zinc iodide, zinc sulfate or zinc acetate; and the supporting electrolyte is any one of lithium salt, sodium salt or potassium salt or a combination of at least two thereof.

5. The negative electrode electrolyte of the zinc-iodine liquid flow battery according to claim 4, characterized in that The lithium salt is lithium chloride, lithium bromide or lithium iodide; the sodium salt is sodium chloride, sodium bromide or sodium iodide; and the potassium salt is potassium chloride, potassium bromide or potassium iodide.

6. A zinc-iodine flow battery comprising a positive electrode, a negative electrode, a separator, a positive electrolyte and a negative electrolyte, characterized in that: The negative electrode electrolyte is the negative electrode electrolyte of the zinc-iodine liquid flow battery according to any one of claims 1 to 5.

7. The zinc-iodine flow battery according to claim 6, characterized in that The positive electrode electrolyte is iodine salt and supporting electrolyte.

8. The zinc-iodine flow battery according to claim 7, characterized in that The concentration of iodide ions in the positive electrode electrolyte is twice the concentration of zinc ions in the negative electrode electrolyte, and the supporting electrolyte in the positive electrode electrolyte is the same as the supporting electrolyte in the negative electrode electrolyte.

9. The zinc-iodine flow battery according to claim 6, characterized in that The positive electrode and the negative electrode are both graphite felt.

10. The zinc-iodine flow battery according to claim 6, characterized in that: The diaphragm is a cation exchange membrane; the cation exchange membrane is a Nafion membrane or a SPEEK membrane.

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