Electrolyte of vanadium battery as well as preparation method and application of electrolyte

Abstract

The invention discloses an electrolyte of a vanadium battery and a preparation method and application thereof, and relates to the technical field of electrolytes.The preparation method comprises the following steps that mesoporous silica is dispersed in an organic solvent, stearic acid and an acid catalyst are added for a reaction, then filtering is conducted, and surface-modified mesoporous silica is obtained; 2-chloro-6-trichloromethylpyridine and ethylene carbonate are mixed, the surface-modified mesoporous silica is added, the mixture is uniformly mixed and then subjected to a reaction, and an additive of the electrolyte is obtained after cooling, filtering and drying; dissolving vanadium sulfate in deionized water, adding concentrated sulfuric acid, and uniformly stirring and mixing to obtain a vanadium sulfate solution; and adding an additive into the vanadium sulfate solution, uniformly mixing, adjusting the pH value of the solution to be acidic, and filtering the obtained solution to obtain the electrolyte of the vanadium battery. The problem that pentavalent vanadium is easy to separate out at a high temperature is solved, meanwhile, excellent stability is achieved in a low-temperature environment, and the capacity retention ratio and coulombic efficiency of the battery are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytes, and in particular to an electrolyte for a vanadium battery, a preparation method thereof, and an application thereof. Background Art

[0002] Vanadium batteries, also known as all-vanadium redox flow batteries, are redox batteries whose active material is a circulating, flowing liquid. They are known for their safety, heat resistance, recyclability, long cycle life, and outstanding scalability. The electrolyte in vanadium batteries is one of their core components. As an energy storage technology, vanadium batteries have attracted widespread attention in recent years in the field of large-scale energy storage due to their high safety, long life, and scalability.

[0003] Currently, vanadium battery electrolytes primarily consist of solutions containing vanadium ions, typically using sulfuric acid as a supporting electrolyte. However, a major issue with current vanadium battery electrolytes is the precipitation of pentavalent vanadium from the cathode electrolyte at high temperatures. To address this issue, the conventional treatment involves adding phosphoric acid to the vanadium battery electrolyte to improve its stability.

[0004] However, although adding phosphoric acid to the electrolyte can improve the stability of the electrolyte to a certain extent, the addition of phosphoric acid will correspondingly change the acidity of the entire electrolyte, thereby increasing the corrosion ability of the electrolyte and shortening the service life of the vanadium battery. Summary of the Invention

[0005] Based on the problem that pentavalent vanadium is easily precipitated in the current vanadium battery electrolyte at high temperature, resulting in low stability of the vanadium battery, the purpose of the present invention is to provide an electrolyte for a vanadium battery and its preparation method and application. The electrolyte prepared by this preparation method not only solves the problem of easy precipitation of pentavalent vanadium at high temperature, but also has excellent stability in a lower temperature environment, and improves the battery's capacity retention rate and coulombic efficiency.

[0006] The present invention is achieved through the following technical solutions: In a first aspect, the present application provides a method for preparing an electrolyte for a vanadium battery, comprising the following steps: Dispersing mesoporous silica in an organic solvent, adding stearic acid and an acidic catalyst, reacting, and then filtering to obtain surface-modified mesoporous silica; 2-chloro-6-trichloromethylpyridine and ethylene carbonate are mixed, and surface-modified mesoporous silica is added, stirred and mixed, and reacted, and then cooled, filtered, and dried to obtain an additive for preparing an electrolyte; Dissolve vanadium sulfate in deionized water, add concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; Additives are added to the vanadium sulfate solution, and after stirring and mixing, the pH value of the solution is adjusted to acidic. The obtained solution is filtered to obtain the electrolyte of the vanadium battery.

[0007] The reaction temperature for surface modification of mesoporous silica is 100°C to 120°C, and the temperature for preparing the additive is controlled at 190°C to 210°C.

[0008] In the electrolyte additive of the present invention, 2-chloro-6-trichloromethyl pyridine is mixed with ethylene carbonate, and then surface-modified mesoporous silica is added to generate a nucleophilic substitution reaction. The surface-modified mesoporous silica can act as a catalyst to open the ring of ethylene carbonate. After the ring opening, the oxygen atom with a partial negative charge attacks the carbon atom connected to the chlorine atom in 2-chloro-6-trichloromethyl pyridine to generate a nucleophilic substitution reaction. The chlorine atom leaves and generates a product containing an open-ring structure of ethylene carbonate connected to 2-chloro-6-trichloromethyl pyridine. The ethylene carbonate carried in the product has a high dielectric constant, making it It can be better dissolved in the vanadium sulfate solution to form more vanadium ions and anions, thereby improving the ionic conductivity of the electrolyte, facilitating the movement of vanadium ions between the positive and negative electrodes, and ensuring the normal charge and discharge process of the battery; at the same time, the lone pair of electrons on the nitrogen atom of the pyridine group in the product will interact with the empty orbital of the vanadium ion in the vanadium sulfate to form a coordination bond, thereby forming a stable complex, effectively inhibiting the self-aggregation and precipitation of vanadium ions at high temperatures, avoiding the precipitation of pentavalent vanadium at high temperatures, and allowing the electrolyte to maintain good chemical stability at high temperatures without adding other stabilizers, thereby improving the reliability and safety of the vanadium battery. On the other hand, since the surface-modified mesoporous silica is loaded with stearic acid, stearic acid has hydrophobic side chains, amino groups and carboxyl groups. These functional groups can effectively increase the solubility and migration rate of vanadium ions in the electrolyte, thereby directly increasing the electrolysis rate, allowing the battery to achieve a faster reaction speed during the charge and discharge process, thereby improving the overall efficiency of the battery, allowing the battery to maintain a higher power output at high current density and achieve the effect of rapid charge and discharge.

[0009] Therefore, the electrolyte additive of the present invention not only solves the problem of easy precipitation of pentavalent vanadium at high temperatures through the mutual synergistic effect between the various components, but also has excellent stability under lower temperature environments, and improves the capacity retention rate and coulombic efficiency of the battery, thereby improving the reliability and safety of the vanadium battery.

[0010] In a specific embodiment, the acidic catalyst includes concentrated sulfuric acid or phosphoric acid.

[0011] In a specific embodiment, the mass ratio of the mesoporous silica to the stearic acid is 1:(2-3).

[0012] In a specific embodiment, the organic solvent includes dimethyl sulfoxide or N,N-dimethylformamide.

[0013] In a specific embodiment, the mass ratio of 2-chloro-6-trichloromethylpyridine, ethylene carbonate, and mesoporous silica is 1: (1-2): (0.5-1).

[0014] In a specific embodiment, when drying the prepared additive, a low-temperature vacuum drying method is adopted, and the drying temperature is controlled at 40°C to 50°C.

[0015] The electrolyte additives are dried by low-temperature vacuum drying to avoid damage to the component structure of the additives caused by high temperature.

[0016] In a specific embodiment, the pH value of the electrolyte of the prepared vanadium battery is adjusted to 2-3.

[0017] In a specific embodiment, 10 g to 30 g of the additive is added to every 1 L of vanadium sulfate solution. In a second aspect, the present application provides an electrolyte for a vanadium battery, which is prepared using the above-mentioned preparation method.

[0018] In a third aspect, the present application provides a vanadium battery, including the above-mentioned vanadium battery electrolyte.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention adds an additive consisting of 2-chloro-6-trichloromethylpyridine, ethylene carbonate, and surface-modified mesoporous silica to the electrolyte, which not only solves the problem of easy precipitation of pentavalent vanadium at high temperatures, but also has excellent stability under low temperature environments, improves the battery's capacity retention rate and coulomb efficiency, and improves the reliability and safety of the vanadium battery.

[0020] (2) The product containing the open-ring structure of ethylene carbonate connected with 2-chloro-6-trichloromethylpyridine generated in the additive of the present invention has a high dielectric constant, which enables it to be better dissolved in the vanadium sulfate solution, forming more vanadium ions and anions, thereby improving the ionic conductivity of the electrolyte, facilitating the movement of vanadium ions between the positive and negative electrodes, and ensuring the normal charging and discharging process of the battery.

[0021] (3) The lone pair of electrons on the nitrogen atom of the pyridine group in the product containing the open-ring structure of ethylene carbonate connected with 2-chloro-6-trichloromethylpyridine generated in the additive of the present invention will interact with the empty orbital of the vanadium ion of vanadium sulfate to form a coordination bond, thereby forming a stable complex, which effectively inhibits the self-aggregation and precipitation of vanadium ions at high temperatures, avoids the precipitation of pentavalent vanadium at high temperatures, enables the electrolyte to maintain good chemical stability in a high-temperature environment, and improves the reliability and safety of vanadium batteries.

[0022] (4) The surface-modified mesoporous silica of the present invention is loaded with stearic acid. Stearic acid has hydrophobic side chains, amino groups and carboxyl groups. These functional groups can effectively increase the solubility and migration rate of vanadium ions in the electrolyte, thereby directly increasing the electrolysis rate, so that the battery can achieve a faster reaction speed during the charge and discharge process, thereby improving the overall efficiency of the battery, enabling the battery to maintain a higher power output at a high current density and achieve a fast charge and discharge effect. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0024] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, well-known materials or methods are not specifically described to avoid obscuring the present invention.

[0025] Throughout this specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment," "an embodiment," "an example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combinations and / or subcombinations. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Furthermore, one skilled in the art will be able to combine and combine different embodiments or examples, and features of different embodiments or examples, described in this specification, without mutual inconsistency.

[0026] The "ranges" disclosed herein are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values ​​and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0028] Example 1 This embodiment provides a method for preparing an electrolyte for a vanadium battery. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0029] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0030] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0031] Example 2 This embodiment provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, in step S1 of this embodiment, the mass ratio of mesoporous silica to stearic acid is 1:2, i.e., the amount of stearic acid added is 20 g, and other process conditions remain unchanged. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 20 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0032] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0033] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0034] Example 3 This embodiment provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, in step S1 of this embodiment, the mass ratio of mesoporous silica to stearic acid is 1:3, i.e., the amount of stearic acid added is 30 g, and other process conditions remain unchanged. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 30 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0035] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0036] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0037] Example 4 This embodiment provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, the mass ratio of 2-chloro-6-trichloromethylpyridine, ethylene carbonate, and mesoporous silica in step S2 of this embodiment is 1:1:0.5, i.e., the amount of 2-chloro-6-trichloromethylpyridine added is 3 g, the amount of ethylene carbonate added is 3 g, and the amount of surface-modified mesoporous silica added is 1.5 g. Other process conditions remain unchanged. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0038] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 3 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0039] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0040] Example 5 This embodiment provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, the mass ratio of 2-chloro-6-trichloromethylpyridine, ethylene carbonate, and mesoporous silica in step S2 of this embodiment is 1:2:1, i.e., the amount of 2-chloro-6-trichloromethylpyridine added is 3 g, the amount of ethylene carbonate added is 6 g, and the amount of surface-modified mesoporous silica added is 3 g. Other process conditions remain unchanged. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0041] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 6 g of ethylene carbonate were mixed, and 3 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0042] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0043] Example 6 This embodiment provides a method for preparing an electrolyte for a vanadium battery. The difference from Example 1 is that the temperature during the drying of the addition in this embodiment is controlled to 40° C. The other process conditions are the same as those in Example 1. The specific preparation steps are as follows: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0044] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 40°C.

[0045] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0046] Example 7 This embodiment provides a method for preparing an electrolyte for a vanadium battery. The difference from Example 1 is that the temperature during the drying of the addition in this embodiment is controlled to 50° C. The other process conditions are the same as those in Example 1. The specific preparation steps are as follows: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0047] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 50°C.

[0048] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0049] Example 8 This embodiment provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, the pH value of the electrolyte for the vanadium battery prepared in this embodiment is adjusted to 3. Other process conditions are the same as those in Example 1. The specific preparation steps are as follows: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0050] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0051] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 3, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0052] Example 9 This embodiment provides a method for preparing an electrolyte for a vanadium battery. The difference from Example 1 is that the amount of the additive in this embodiment is 2 g. Other process conditions are the same as those in Example 1. The specific preparation steps are as follows: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0053] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0054] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 0.5 g of the electrolyte additive in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0055] Example 10 This embodiment provides a method for preparing an electrolyte for a vanadium battery. The difference from Example 1 is that the amount of the additive in this embodiment is 3 g. The other process conditions are the same as those in Example 1. The specific preparation steps are as follows: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0056] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of the surface-modified mesoporous silica prepared in step S1 was added. The mixture was stirred and reacted, and the electrolyte additive was obtained after cooling, filtering, and drying. Drying was performed by low-temperature vacuum drying at 45°C.

[0057] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1.5 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0058] Comparative Example 1 This comparative example provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, this comparative example does not perform surface modification on the mesoporous silica. Other processes are the same as Example 1. The specific preparation steps are: S1. Preparation of electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine and 4.5 g of ethylene carbonate were mixed, and 1.5 g of mesoporous silica was added. The mixture was stirred and reacted, and then cooled, filtered, and dried to obtain an additive for preparing an electrolyte. Drying was performed by low-temperature vacuum drying at a temperature of 45°C.

[0059] S2. Preparation of electrolyte for vanadium battery S2-1, dissolve 30g of vanadium sulfate in 50ml of deionized water, and add 10ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S2-2, adding 1 g of the electrolyte additive in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0060] Comparative Example 2 This comparative example provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, this comparative example does not add 2-chloro-6-trichloromethylpyridine and ethylene carbonate. The other processes are the same as Example 1. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0061] S2. Preparation of electrolyte for vanadium battery S2-1, dissolve 30g of vanadium sulfate in 50ml of deionized water, and add 10ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S2-2. Add 1 g of surface-modified mesoporous silica to the vanadium sulfate solution, stir and mix, adjust the pH value of the solution to 2, filter the resulting solution to remove impurities, and obtain the electrolyte of the vanadium battery.

[0062] Comparative Example 3 This comparative example provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, 2-chloro-6-trichloromethylpyridine is not added in this comparative example, and the other processes are the same as Example 1. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0063] S2. Electrolyte additives 1.5 g of surface-modified mesoporous silica was mixed with 4.5 g of ethylene carbonate, stirred and mixed, and reacted. The mixture was cooled, filtered, and dried to obtain an additive for preparing an electrolyte solution. The drying step was performed by low-temperature vacuum drying at 45°C.

[0064] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0065] Comparative Example 4 This comparative example provides a method for preparing an electrolyte for a vanadium battery. Unlike Example 1, ethylene carbonate is not added in this comparative example, and the other processes are the same as Example 1. The specific preparation steps are: S1. Preparation of surface-modified mesoporous silica 10 g of mesoporous silica was dispersed in 200 ml of dimethyl sulfoxide, and 25 g of stearic acid and 5 ml of concentrated sulfuric acid were added. The mixture was reacted at 110° C. and then filtered to obtain surface-modified mesoporous silica.

[0066] S2. Electrolyte additives 3 g of 2-chloro-6-trichloromethylpyridine was mixed with 1.5 g of the surface-modified mesoporous silica prepared in step S1, stirred and mixed, and reacted. The mixture was cooled, filtered, and dried to obtain an additive for preparing an electrolyte. Drying was performed by low-temperature vacuum drying at 45°C.

[0067] S3. Preparation of electrolyte for vanadium battery S3-1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S3-2, adding 1 g of the electrolyte additive prepared in step S2 to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to 2, filtering the resulting solution to remove impurities, and obtaining an electrolyte for a vanadium battery.

[0068] Comparative Example 5 This comparative example is a method for preparing an electrolyte for a vanadium battery. The difference from Example 1 is that no additives are added in this comparative example, and the other processes are the same as Example 1. The specific preparation steps are: S1. Dissolve 30 g of vanadium sulfate in 50 ml of deionized water, and add 10 ml of concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; S2. Adjust the pH value of the solution to 2, and filter the resulting solution to remove impurities to obtain an electrolyte for a vanadium battery.

[0069] The electrolytes prepared by the methods of Examples 1 to 10 and Comparative Examples 1 to 5 were loaded into the test unit of the vanadium battery, and the stability of the electrolyte, including the capacity and internal resistance of the battery, was tested for each sample at -20°C and 50°C.

[0070] Table 1

[0071] According to the above test data, the electrolyte prepared by the method of the present invention exhibits lower internal resistance and higher capacity retention rate in both -20°C and 50°C environments, proving that the electrolyte prepared by the method of the present invention can maintain good chemical stability in extremely high and low temperature environments, thereby improving the reliability and safety of vanadium batteries.

[0072] The electrolytes prepared using the methods of Examples 1-10 and Comparative Examples 1-5 were loaded into a vanadium battery test cell for performance testing. Each sample was subjected to 200 charge-discharge cycles, and the capacity retention and coulombic efficiency after 200 charge-discharge cycles were recorded. The battery was charged to 1.8V and discharged to 0.8V. At cycle 0, the capacity retention and coulombic efficiency were both 100%. The test results are shown in Table 2.

[0073] Table 2

[0074] From the test data in the above table, it can be seen that the capacity retention rate of the electrolyte prepared by the method of the present invention after 200 cycles is higher than that of the comparative example. At the same time, the coulombic efficiency of the electrolyte prepared by the method of the present invention after 200 cycles only decreases a little, while the coulombic efficiency in the comparative example decreases significantly. It is proved that the chemical properties of the electrolyte prepared by the method of the present invention are more stable than those of the comparative example during the cycle, thereby proving that the synergistic effect between the various components of the additive in this application can effectively inhibit the degradation of the electrolyte and improve the life and energy efficiency of the battery.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that it is still possible to modify the technical solutions described in the above embodiments, or to replace some or all of the technical features therein by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A method for preparing an electrolyte for a vanadium battery, characterized in that: The following steps are involved: Dispersing mesoporous silica in an organic solvent, adding stearic acid and an acidic catalyst, reacting, and then filtering to obtain surface-modified mesoporous silica; 2-chloro-6-trichloromethylpyridine and ethylene carbonate are mixed, and surface-modified mesoporous silica is added, stirred and mixed, and reacted, and then cooled, filtered, and dried to obtain an additive for preparing an electrolyte; Dissolve vanadium sulfate in deionized water, add concentrated sulfuric acid and stir to obtain a vanadium sulfate solution; Adding additives to the vanadium sulfate solution, stirring and mixing, adjusting the pH value of the solution to acidic, and filtering the obtained solution to obtain the electrolyte of the vanadium battery.

2. The method for preparing an electrolyte for a vanadium battery according to claim 1, characterized in that: The acidic catalyst includes concentrated sulfuric acid or phosphoric acid.

3. The method for preparing an electrolyte for a vanadium battery according to claim 1, characterized in that: The mass ratio of the mesoporous silica to the stearic acid is 1:(2-3).

4. The method for preparing an electrolyte for a vanadium battery according to claim 1, characterized in that: The organic solvent includes dimethyl sulfoxide or N,N-dimethylformamide.

5. The method for preparing an electrolyte for a vanadium battery according to claim 1, characterized in that: The mass ratio of the 2-chloro-6-trichloromethylpyridine, ethylene carbonate and mesoporous silica is 1: (1-2): (0.5-1).

6. The method for preparing an electrolyte for a vanadium battery according to claim 1, characterized in that: When drying the prepared additive, a low-temperature vacuum drying method is adopted, and the drying temperature is controlled at 40°C to 50°C.

7. The method for preparing an electrolyte for a vanadium battery according to claim 1, characterized in that: The pH value of the electrolyte of the prepared vanadium battery is adjusted to 2~3.

8. The method for preparing an electrolyte for a vanadium battery according to claim 1, characterized in that: Add 10g~30g of additives per 1L of vanadium sulfate solution.

9. An electrolyte for a vanadium battery, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. A vanadium battery, characterized in that: An electrolyte for a vanadium battery comprising the electrolyte of claim 9.

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