Electrolyte additive, electrolyte as well as preparation method and application of electrolyte

Abstract

The invention relates to an electrolyte additive, an electrolyte as well as a preparation method and application of the electrolyte. The additive comprises an amine compound and a tertiary alcohol compound; the mass ratio of the amine compound to the tertiary alcohol compound is 10: (3-5). The electrolyte additive can significantly promote the generation of Zn (002) type crystals, effectively inhibit the hydrogen evolution side reaction (HER) of a negative electrode, and improve the reversibility of a negative electrode electrolyte, thereby improving the energy efficiency of a battery, and effectively improving the capacity retention rate of the battery.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to an electrolyte additive, an electrolyte, and a preparation method and application thereof. Background Art

[0002] As global energy demand continues to rise and there is an urgent need for clean energy storage, large-scale energy storage technology has become a research hotspot. Liquid flow batteries have shown great potential in the field of large-scale energy storage due to their unique working principle and the ability to flexibly adjust power and capacity. Among them, alkaline zinc-based liquid flow batteries have good application prospects due to their outstanding advantages such as low cost, abundant raw materials, high safety (using alkaline electrolyte, non-flammable and non-explosive), and environmental friendliness.

[0003] However, alkaline zinc-based flow batteries still face many challenges in practical applications. The dendrite growth of the zinc negative electrode and the hydrogen evolution side reaction (HER) are particularly prominent. The growth of zinc dendrites is uncontrollable. As the charge and discharge cycle proceeds, zinc dendrites will continue to grow and gradually pierce the diaphragm inside the battery, causing an internal short circuit in the battery and making the battery unable to work properly. At the same time, the formation of zinc dendrites will also cause the loss of active zinc, resulting in a reduction in zinc participating in the electrochemical reaction, resulting in a decrease in coulombic efficiency and accelerated battery capacity decay, which severely limits the cycle life and performance stability of the battery, and greatly hinders the commercialization and large-scale application of alkaline zinc-based flow batteries.

[0004] Therefore, the traditional technology still needs to be improved. Summary of the invention

[0005] Based on this, the present application provides an electrolyte additive, an electrolyte, and a preparation method and application thereof. The electrolyte additive can significantly promote the generation of Zn(002) type crystals, effectively inhibit the hydrogen evolution side reaction (HER) of the negative electrode, and improve the reversibility of the negative electrode electrolyte, thereby improving the energy efficiency of the battery and effectively improving the capacity retention rate of the battery.

[0006] This application is implemented through the following technical solutions:

[0007] One aspect of the present application provides an electrolyte additive, the additive comprising an amine compound and a tertiary alcohol compound; the mass ratio of the amine compound to the tertiary alcohol compound is 10:(3-5).

[0008] The electrolyte additives in the present application include amine compounds and tertiary alcohol compounds of a specific ratio. The amino group in the amine compound has a strong affinity for zinc ions, and the amine compound can be closely combined on the zinc surface by chemical reaction or physical adsorption, providing guidance for the arrangement of zinc atoms, inducing the generation of Zn (002) crystal form, ensuring that the deposition morphology is relatively flat, reducing the generation of zinc dendrites, and reducing the hydrogen evolution potential at the same time, inhibiting the hydrogen evolution side reaction; tertiary alcohol can avoid the generation of large-particle-size layered zinc oxide passivation byproducts when zinc loses electrons on the surface, and reduce the high interface impedance effect caused by the accumulation of zinc oxide on the electrode surface after the cycle. In addition, the hydroxyl group in the tertiary alcohol molecule can also provide additional hydrogen bonding sites, improve the hydrogen bonding network in the solution, and further inhibit the hydrogen evolution effect, so that the amine compound and the tertiary alcohol compound synergistically act in the liquid flow battery, improve the reversibility of the negative electrode electrolyte, enhance the cycle stability of the battery, effectively improve the capacity retention rate of the battery, and extend the service life of the battery.

[0009] In some embodiments, the amine compound includes an aromatic amine compound.

[0010] In some embodiments, the amine compound includes at least one of 2,4-diaminotoluene, 2-aminoethanesulfonic acid, sodium sulfacetamide, sodium p-aminobenzenesulfonate, 4-amino-1-naphthalenesulfonic acid and m-phenylenediamine.

[0011] In some embodiments, the tertiary alcohol compound satisfies at least one of the conditions (1) to (2):

[0012] (1) The tertiary alcohol compound is an alkane tertiary alcohol compound;

[0013] Optionally, the tertiary alcohol compound is a chain alkane tertiary alcohol compound;

[0014] (2) The tertiary alcohol compound has 4 to 8 carbon atoms;

[0015] Optionally, the tertiary alcohol compound includes at least one of 2-methyl-2-propanol, 2-methyl-2-butanol, 2-hexanol, and 4-methyl-2-pentanol.

[0016] In some of the embodiments, the mass ratio of the amine compound to the tertiary alcohol compound is 10:(3-4).

[0017] Another aspect of the present application provides an electrolyte for a zinc-based flow battery, wherein the components of the electrolyte include the electrolyte additive as described above, a zinc salt, and a solvent.

[0018] In some of the embodiments, the mass concentration of the electrolyte additive in the electrolyte is 0.15 g / L~0.2 g / L.

[0019] In some embodiments, the zinc salt includes at least one of zinc acetate, zinc oxide, potassium zincate and sodium zincate;

[0020] And / or, the concentration of the zinc salt is 0.30 mol / L~0.40 mol / L.

[0021] Another aspect of the present application provides a method for preparing the electrolyte as described above, comprising the following steps: mixing the zinc salt, the electrolyte additive and the solvent to prepare the electrolyte.

[0022] Another aspect of the present application provides a zinc-based liquid flow battery, which includes a positive electrode, a negative electrode, a separator, and the electrolyte as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 X-ray diffraction (Xrd) image of zinc deposition of the battery prepared with the electrolyte in Example 1 after cycling;

[0024] Figure 2 Scanning electron microscopy (SEM) images of zinc deposition on the surface of the batteries prepared with the electrolytes in Example 1 and Comparative Example 1 after cycling;

[0025] Figure 3 The voltage-specific capacity diagram of the battery prepared with the electrolyte in Examples 1 to 4;

[0026] Figure 4 The voltage-specific capacity diagram of the battery prepared with the electrolyte in Examples 5-6;

[0027] Figure 5 The voltage-specific capacity diagram of the battery prepared with the electrolyte in Comparative Examples 2 to 3;

[0028] Figure 6 This is a graph showing the capacity retention rate of the battery prepared with the electrolyte in Example 1. DETAILED DESCRIPTION

[0029] For ease of understanding of the present application, the present application will be described more fully below, and preferred embodiments of the present application are provided. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0030] The implementation of this application is described in detail below in combination with some implementation methods and examples. This example is implemented based on the technical solution of this application, and provides a detailed implementation method and specific operation process, but the protection scope of this application is not limited to the following examples.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0032] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0033] The terms "and / or", "or / and", and "and / or" used in this article include any one of two or more related listed items, and also include any and all combinations of related listed items, and the arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions that are all connected by "logical and", and undoubtedly includes technical solutions that are all connected by "logical or". For example, "A and / or B" includes three parallel solutions of A, B and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, the technical solution that is all connected by "logical OR"), and also includes any and all combinations of A, B, C, and D, that is, the combination of any two or any three of A, B, C, and D, and also includes the combination of four of A, B, C, and D (that is, the technical solution that is all connected by "logical AND").

[0034] In the present application, "plurality", "multiple" and the like, unless otherwise specified, refer to a number greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0035] In the present application, the terms "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0036] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0037] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0038] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical range disclosed herein should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0039] In this application, unless otherwise specified, the temperature parameter is allowed to be either a constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0040] In this application, when referring to the unit of a data range, if there is a unit only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 2~5h means that the units of the left endpoint "2" and the right endpoint "5" are both h (hours).

[0041] As shown in the background technology, some metal deposition additives are used to protect zinc negative electrodes in traditional technologies, but the principle determines that the metal cations in the additives must be deposited and stripped synchronously with zinc. This process causes the embedding and extraction of additional metal ions on the electrode surface, resulting in instability of the electrode-electrolyte interface (SEI). Moreover, when this type of additive is applied to a flow battery, due to the potential gradient in the series circuit, it will be unevenly deposited on multiple pole pieces inside the flow battery stack, further increasing the inconsistency of the flow battery and seriously affecting the normal operation of the flow battery.

[0042] Based on this, one embodiment of the present application provides an electrolyte additive, the additive includes an amine compound and a tertiary alcohol compound; the mass ratio of the amine compound to the tertiary alcohol compound is 10: (3~5).

[0043] As an example, the mass ratio of the amine compound to the tertiary alcohol compound may be 10:3, 10:3.5, 10:4, 10:4.5 and 10:5, or may be within a range consisting of any two of the above point values ​​as end values. Optionally, the mass ratio of the amine compound to the tertiary alcohol compound is 10:(3-4.5).

[0044] The electrolyte additives in the present application include amine compounds and tertiary alcohol compounds of a specific ratio. The amino group in the amine compound has a strong affinity for zinc ions, and the amine compound can be closely combined on the zinc surface by chemical reaction or physical adsorption, providing guidance for the arrangement of zinc atoms, inducing the generation of Zn (002) crystal form, ensuring that the deposition morphology is relatively flat, reducing the generation of zinc dendrites, and reducing the hydrogen evolution potential at the same time, inhibiting the hydrogen evolution side reaction; tertiary alcohol can avoid the generation of large-particle-size layered zinc oxide passivation byproducts when zinc loses electrons on the surface, and reduce the high interface impedance effect caused by the accumulation of zinc oxide on the electrode surface after the cycle. In addition, the hydroxyl group in the tertiary alcohol molecule can also provide additional hydrogen bonding sites, improve the hydrogen bonding network in the solution, and further inhibit the hydrogen evolution effect, so that the amine compound and the tertiary alcohol compound synergistically act in the liquid flow battery, improve the reversibility of the negative electrode electrolyte, enhance the cycle stability of the battery, effectively improve the capacity retention rate of the battery, and extend the service life of the battery.

[0045] In some embodiments, the amine compound includes an aromatic amine compound.

[0046] It can be understood that the anchoring effect of zinc-philic groups such as amino groups on the zinc surface is used to induce the generation of Zn(002), and the amino groups are fixed by aromatic groups to increase their stability under alkaline conditions and enhance the reversibility of zinc.

[0047] In some embodiments, the amine compound includes at least one of 2,4-diaminotoluene, 2-aminoethanesulfonic acid, sodium sulfacetamide, sodium p-aminobenzenesulfonate, 4-amino-1-naphthalenesulfonic acid and m-phenylenediamine.

[0048] In some embodiments, the tertiary alcohol compound is an alkane tertiary alcohol compound.

[0049] In some embodiments, the tertiary alcohol compound is a chain alkane tertiary alcohol compound.

[0050] In some embodiments, the tertiary alcohol compound has 4 to 8 carbon atoms.

[0051] In some embodiments, the tertiary alcohol compound includes at least one of 2-methyl-2-propanol, 2-methyl-2-butanol, 2-hexanol, and 4-methyl-2-pentanol.

[0052] It can be understood that the mechanism of the role of hydroxyl groups in the above-mentioned tertiary alcohol compounds is mainly reflected in the fact that hydroxyl groups in tertiary alcohol compounds strengthen hydrogen bonding forces: the hydroxyl (-OH) oxygen atom in the tertiary alcohol has a large electronegativity and can act as a hydrogen bond acceptor to form hydrogen bonds with a small amount of water molecules in the solvation sheath of the zinc ion. When tertiary alcohols are added to the solution, the tertiary alcohol hydroxyl groups participate in the formation of a hydrogen bond network, replacing part of the weak hydrogen bonding between water and water to form a strong hydrogen bonding between hydroxyl groups and water. This enhanced hydrogen bonding can increase the deprotonation energy barrier of water molecules, thereby reducing the activity of water molecules during the charge and discharge process and inhibiting the hydrogen evolution reaction (HER).

[0053] In some of the embodiments, the mass ratio of the amine compound to the tertiary alcohol compound is 10:(3-4).

[0054] It can be understood that by controlling the mass ratio of the above-mentioned amine compound and the above-mentioned tertiary alcohol compound within the above-mentioned range, the reversibility of the negative electrode electrolyte is better, thereby improving the energy efficiency of the battery and effectively improving the capacity retention rate of the battery.

[0055] One embodiment of the present application also includes an electrolyte for a zinc-based liquid flow battery, and the components of the electrolyte include the above-mentioned electrolyte, a zinc salt and a solvent.

[0056] In some of the embodiments, the mass concentration of the electrolyte additive in the above electrolyte is 0.15 g / L~0.2 g / L.

[0057] It can be understood that specific additives at appropriate concentrations can adjust the physical properties of the electrolyte, such as ionic conductivity and viscosity, promote the transport of zinc ions in the electrolyte, and enable the battery to maintain good performance under different working conditions.

[0058] In some embodiments, the zinc salt includes at least one of zinc acetate, zinc oxide, potassium zincate and sodium zincate.

[0059] In some embodiments, the concentration of the zinc salt is 0.30 mol / L-0.40 mol / L.

[0060] It is understandable that increasing the zinc salt concentration can provide more zinc ions and improve ion conductivity, and the appropriate zinc salt concentration helps to form a stable solid-liquid interface layer on the electrode surface, which can prevent the side reaction between the electrode material and the electrolyte, inhibit the uneven growth of zinc dendrites, and maintain the integrity of the electrode structure, thereby extending the cycle life of the battery and improving the safety of the battery. However, too high a zinc ion concentration will affect the viscosity of the electrolyte and reduce the ion migration rate.

[0061] An embodiment of the present application further provides a method for preparing the above-mentioned electrolyte, comprising the following steps: mixing the above-mentioned zinc salt, the above-mentioned electrolyte additive and the above-mentioned solvent to prepare the electrolyte.

[0062] The electrolyte preparation method is simple to operate, and the prepared electrolyte helps to enhance the cycle stability of the battery, effectively improve the capacity retention rate of the battery, and extend the service life of the battery.

[0063] An embodiment of the present application further provides a zinc-based liquid flow battery, which includes a positive electrode, a negative electrode, a separator and the above-mentioned electrolyte.

[0064] In some embodiments, the positive electrode includes one or more of ferrocyanide, manganese-based oxide, vanadium-based oxide, Prussian blue analogs, carbon felt or graphite felt.

[0065] In some embodiments, the negative electrode is metallic zinc or an alloy containing zinc.

[0066] In some of the embodiments, the zinc-based flow battery includes but is not limited to a zinc-iron battery, a zinc-nickel battery, a zinc-manganese battery, and a zinc-silver battery.

[0067] In a specific example, during charging, zincate ions gain electrons at the negative electrode and are reduced to zinc, while potassium ferrocyanide or potassium ferrocyanide loses electrons at the positive electrode and is oxidized. The discharge process is the opposite, with zinc losing electrons at the negative electrode to become zincate ions and enter the electrolyte, undergoing an oxidation reaction; potassium ferrocyanide or potassium ferrocyanide gains electrons at the positive electrode and undergoes a reduction reaction to generate potassium ferrocyanide or potassium ferrocyanide.

[0068] In order to make the purpose, technical solutions and advantages of the present application more concise and clear, the present application is described with the following specific embodiments, but the present application is by no means limited to these embodiments. The embodiments described below are only preferred embodiments of the present application and can be used to describe the present application, and cannot be understood as limiting the scope of the present application. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0069] In order to better illustrate the present application, the contents of the present application are further described below in conjunction with embodiments.

[0070] The present application is further described below in conjunction with specific embodiments, but they should not be construed as limiting the scope of protection of the present application.

[0071] Example 1

[0072] 1. Electrolyte additives: the amine compound is sodium sulfacetamide, the tertiary alcohol compound is 2-methyl-2-propanol, and the mass ratio of the above amine compound to the above tertiary alcohol compound is 10:3.

[0073] 2. The specific method for preparing the electrolyte is: adding zinc salt (specifically zinc acetate) to a potassium hydroxide solution, and then adding the above electrolyte additive, stirring evenly to obtain an electrolyte; wherein the concentration of the zinc salt is 0.30 mol / L, and the mass concentration of the electrolyte additive is 0.2 g / L.

[0074] Example 2

[0075] The preparation methods of the electrolytes of Example 2 and Example 1 are basically the same, the only difference being that the mass ratio of the amine compound to the tertiary alcohol compound is different, specifically 10:3.5.

[0076] Other conditions and parameters are the same as those in Example 1.

[0077] Example 3

[0078] The preparation methods of the electrolytes of Example 3 and Example 1 are basically the same, except that the mass ratio of the amine compound to the tertiary alcohol compound is different, specifically 10:4.

[0079] Other conditions and parameters are the same as those in Example 1.

[0080] Example 4

[0081] The preparation methods of the electrolytes of Example 4 and Example 1 are basically the same, except that the mass ratio of the amine compound to the tertiary alcohol compound is different, specifically 10:5.

[0082] Other conditions and parameters are the same as those in Example 1.

[0083] Example 5

[0084] The preparation methods of the electrolytes of Example 5 and Example 1 are basically the same, the only difference being the type of the amine compound, specifically sodium p-aminobenzenesulfonate.

[0085] Other conditions and parameters are the same as those in Example 1.

[0086] Example 6

[0087] The preparation methods of the electrolytes of Example 6 and Example 1 are basically the same, the only difference being the types of amine compounds and tertiary alcohol compounds, specifically 2,4-diaminotoluene and 2-methyl-2-butanol.

[0088] Other conditions and parameters are the same as those in Example 1.

[0089] Example 7

[0090] The preparation methods of the electrolytes of Example 7 and Example 1 are basically the same, the only difference being the type of the amine compound, specifically 2-aminoethanesulfonic acid.

[0091] Other conditions and parameters are the same as those in the embodiment.

[0092] Comparative Example 1

[0093] The preparation methods of the electrolytes of Comparative Example 1 and Example 1 are basically the same, except that only amine compounds are added without adding tertiary alcohol compounds.

[0094] Other conditions and parameters are the same as those in Example 1.

[0095] Comparative Example 2

[0096] The preparation methods of the electrolytes of Comparative Example 2 and Example 1 are basically the same, except that the types of electrolyte additives are different, specifically sodium 3-mercapto-propanesulfonate and 2-methyl-2-butanol.

[0097] Other conditions and parameters are the same as those in Example 1.

[0098] Comparative Example 3

[0099] The preparation methods of the electrolytes of Comparative Example 3 and Example 1 are basically the same, except that the mass ratio of the amine compound to the tertiary alcohol compound is different, specifically 10:2.

[0100] Other conditions and parameters are the same as those in Example 1.

[0101] Performance Test:

[0102] 1. The electrolytes prepared in the embodiments and comparative examples were assembled into batteries (the positive and negative electrodes were a mixed solution of sodium ferrocyanide and potassium hydroxide, and a mixed solution of zinc acetate and potassium hydroxide, respectively). X-ray diffraction tests were performed, and the samples were specifically tested using a Bruker D8-ADVANCE X-ray diffractometer. The test conditions were as follows: a Cu Kα target was used as the X-ray source, with a wavelength of λ=1.5406 Å, a tube voltage set to 40 kV, and a tube current of 30 mA. The sample was evenly spread or pressed on the sample table to ensure that the sample surface was flat. The scanning range was set to 2θ = 20° to 80°, and the scanning speed was 2° / min. The standard powder diffraction file (PDF) database was used as a comparison basis, and the crystal structure and phase composition of the sample were characterized by analyzing the position, intensity and peak shape of the diffraction peaks. The test process followed the relevant standards and specifications specified by the International Center for Diffraction Data (ICDD) to ensure the accuracy and reliability of the test results.

[0103] 2. The electrolytes prepared in the embodiments and comparative examples were assembled into batteries, and the deposited materials on the surface of the negative electrode were scraped off after the cycle for microscopic observation. Specifically, the JEOL JSM-IT500HR Japanese scanning electron microscope (SEM) was used to observe the microscopic morphology of the samples. Under high vacuum conditions, the acceleration voltage was adjusted to 10 kV, and the working distance was set to 3 mm. The surface of the sample was scanned point by point by an electron beam, and the secondary electron signal and the backscattered electron signal were collected to obtain the surface morphology image of the sample. The magnification range of the image was 10-200kx.

[0104] 3. The electrolytes prepared in the examples and comparative examples were assembled into batteries for charge and discharge tests, specifically using the Neware CT-4008 battery test system. The prepared batteries (or electrodes) were installed in the test system according to the prescribed connection method. The test electrolyte was a solution of 0.3M zinc acetate and 6.8M KOH. The specific steps of the charge and discharge test are as follows: Charging process: The constant current constant power (CC-CP) charging mode was adopted, first at 35mA / cm 2 The battery is charged at a constant current density of 225W / kg. When the battery voltage reaches 1.9V, it is charged at a constant power density of 225W / kg until the charging voltage reaches 2.0V. The charging process ends. Discharge process: After charging, let it stand for 10 minutes, then discharge at a constant power density of 225W / kg. When the battery voltage drops to 1.45V, the discharge process ends.

[0105] Cycle test: Perform multiple cycles according to the above charge and discharge steps, the number of cycles is 80, and record the charge and discharge capacity, charge and discharge voltage curve and other data of each cycle. During the test, refer to the industry T / HNSDCHYXH 002-2024 zinc-iron liquid flow battery general requirements, and strictly control the temperature and humidity of the test environment, the temperature is maintained at 25℃±5℃, and the humidity is controlled at 15%±5% to ensure the comparability and accuracy of the test results.

[0106] 4. The electrolytes prepared in the embodiments and comparative examples were assembled into batteries and the capacity retention rate was tested, using the same assembly and testing process as in item 3.

[0107] Figure 1 The X-ray diffraction (Xrd) image of zinc deposition in the battery prepared with the electrolyte in Example 1 after cycling indicates that the Zn (002) crystal form is successfully induced after adding the additive of this example; Figure 2Scanning electron microscopy (SEM) images of zinc deposition on the surface of batteries prepared with the electrolytes in Example 1 and Comparative Example 1 after cycling. Left: additives in Example 1. Right: additives containing only aromatic amines. It can be seen from the figure that after the addition of a tertiary alcohol in this example, the particle size of zinc oxide produced on the surface is significantly reduced, avoiding the high interface impedance caused by the insulating properties and layered structure of zinc oxide, reducing the loss of charge during interface transfer, and improving the overall efficiency of the battery. Figure 3 The voltage-specific capacity diagram of the battery prepared with the electrolyte in Examples 1 to 4 shows that the optimal specific capacity and reversibility of the battery are achieved at a ratio of 10:3.5; the slope of the curve shows that when the mixing ratio is 10:3.5, the efficiency of charge transfer at the end of charge and discharge is significantly improved. Figure 4 The voltage-specific capacity diagram of the battery prepared with the electrolyte in Example 5 and Example 6, Figure 5 The voltage-specific capacity diagram of the batteries prepared with the electrolytes in Comparative Examples 2 and 3. Figure 6 This is a graph showing the capacity retention rate of a battery prepared with the electrolyte in Example 1. After adding the additive of this example to the electrolyte, the battery achieves a decay rate of only 0.004% per cycle at a high power density of 225 W / kg.

[0108] In summary, compared with the electrolyte additive of the comparative example, the electrolyte additive of the present application can significantly promote the generation of Zn(002) type crystals, effectively inhibit the hydrogen evolution side reaction (HER) of the negative electrode, improve the reversibility of the negative electrode electrolyte, thereby improving the energy efficiency of the battery, and effectively improve the capacity retention rate of the battery.

[0109] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0110] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. An electrolyte additive, characterized in that: The additives include amine compounds and tertiary alcohol compounds; the mass ratio of the amine compounds to the tertiary alcohol compounds is 10:(3-5).

2. The electrolyte additive according to claim 1, characterized in that The amine compounds include aromatic amine compounds.

3. The electrolyte additive according to claim 1, characterized in that The amine compound includes at least one of 2,4-diaminotoluene, 2-aminoethanesulfonic acid, sodium sulfacetamide, sodium p-aminobenzenesulfonate, 4-amino-1-naphthalenesulfonic acid and m-phenylenediamine.

4. The electrolyte additive according to any one of claims 1 to 3, characterized in that The tertiary alcohol compound satisfies at least one of the conditions (1) to (2): (1) The tertiary alcohol compound is an alkane tertiary alcohol compound; Optionally, the tertiary alcohol compound is a chain alkane tertiary alcohol compound; (2) The tertiary alcohol compound has 4 to 8 carbon atoms; Optionally, the tertiary alcohol compound includes at least one of 2-methyl-2-propanol, 2-methyl-2-butanol, 2-hexanol, and 4-methyl-2-pentanol.

5. The electrolyte additive according to any one of claims 1 to 3, characterized in that The mass ratio of the amine compound to the tertiary alcohol compound is 10:(3-4).

6. An electrolyte for a zinc-based flow battery, characterized in that: The components of the electrolyte include the electrolyte additive according to any one of claims 1 to 5, a zinc salt and a solvent.

7. The electrolyte according to claim 6, characterized in that The mass concentration of the electrolyte additive in the electrolyte is 0.15 g / L~0.2 g / L.

8. The electrolyte according to claim 6 or 7, characterized in that The zinc salt comprises at least one of zinc acetate, zinc oxide, potassium zincate and sodium zincate; The concentration of the zinc salt is 0.30 mol / L~0.40 mol / L.

9. A method for preparing an electrolyte according to any one of claims 6 to 8, characterized in that: The method comprises the following steps: mixing the zinc salt, the electrolyte additive and the solvent to prepare the electrolyte.

10. A zinc-based liquid flow battery, characterized in that: The zinc-based flow battery comprises a positive electrode, a negative electrode, a separator and an electrolyte as claimed in any one of claims 6 to 8.

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