Electrolyte, preparation method and all-vanadium redox flow battery

Abstract

The application belongs to the technical field of electrochemical energy storage and provides an electrolyte, a preparation method and a full vanadium redox flow battery. The electrolyte comprises an acidic electrolyte, vanadyl sulfate, an additive and water, the additive is 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid or 3-aminopropanesulfonic acid, the concentration of the acidic electrolyte in the electrolyte is 3.0-3.5 mol / L, the concentration of the vanadyl sulfate is 1.7-2.0 mol / L, and the concentration of the additive is 0.05-0.25 mol / L. The electrolyte can improve the high-temperature stability of VO2 + under the premise of ensuring good electrochemical performance.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to an electrolyte and its preparation method, and an all-vanadium redox flow battery. Background Technology

[0002] With the increasing prominence of clean energy, the demand for energy storage technologies is becoming more diversified. Flow batteries, as a highly efficient and sustainable medium- to long-term energy storage technology, have attracted significant attention. Vanadium redox flow batteries (VRFBs) have become an important candidate technology for large-scale energy storage due to their advantages such as the storage of active materials in a liquid electrolyte, independent design of power and capacity, and long cycle life. During the charging process of a VRFB, the VO in the positive electrode electrolyte... 2+ Converted to VO2 + However, as the charging process progresses, the temperature continuously rises, and at high temperatures (typically exceeding 40°C), VO2... + Severe precipitation will occur, which is essentially caused by the strong oxidizing VO2. + Ions undergo hydrolysis, generating readily polymerizable intermediates, which then condense via oxygen or hydroxyl bridges to form water-insoluble macromolecular polyvanadates such as decavanadates, ultimately forming an orange-red V₂O₅·xH₂O gel-like precipitate. High temperatures significantly accelerate this hydrolysis-polymerization chain reaction and reduce the solubility of the products. Simultaneously, the accompanying oxygen evolution side reaction consumes hydrogen ions, raising the local pH and further catalyzing the aforementioned hydrolysis-polymerization chain reaction process. VO₂ + The precipitate formation of ions at high temperatures is systemic and fatal. It irreversibly consumes active materials, leading to a sharp drop in battery capacity. Simultaneously, the formed gel-like precipitate clogs porous electrodes and channels, significantly increasing pump consumption and hindering ion transport, resulting in a drastic decrease in battery efficiency and output power. Ultimately, this can cause system cycle failure and safety risks, completely destroying the battery's long-term operational stability and lifespan. Therefore, suppressing VO2... + High-temperature precipitation of ions is key to achieving stable high-temperature operation of vanadium redox flow batteries.

[0003] To address these issues, researchers have experimented with adding various additives to the electrolyte. For example, phosphoric acid is added, its key advantage being that phosphate ions can react with VO2. + The ions form stable and soluble complexes, thereby significantly inhibiting VO2. + The precipitation of ions at high temperatures effectively broadens the battery's operating temperature range and improves cycle life; however, the benefits of adding phosphoric acid come at the cost of sacrificing electrochemical performance, which reduces electrolyte conductivity, increases battery polarization, leads to a decrease in voltage efficiency and energy output, and may trigger negative electrode side reactions.

[0004] Therefore, it is necessary to develop a method to improve VO2 while ensuring good electrochemical performance. + High-temperature stable electrolytes are a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To overcome the limitations of existing technologies in increasing VO2 content in the positive electrode electrolyte of vanadium redox batteries... + To address the problem of decreased electrochemical performance due to high-temperature stability, this invention provides an electrolyte, its preparation method, and an all-vanadium redox flow battery, which can improve VO2 while maintaining good electrochemical performance. + High temperature stability.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides an electrolyte comprising: an acidic electrolyte, vanadium oxysulfate, an additive, and water, wherein the additive is 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, or 3-aminopropanesulfonic acid; wherein the concentration of the acidic electrolyte in the electrolyte is 3.0~3.5 mol / L, the concentration of vanadium oxysulfate is 1.7~2.0 mol / L, and the concentration of the additive is 0.05~0.25 mol / L.

[0008] Preferably, the additive is 5-amino-2-naphthalenesulfonic acid.

[0009] Furthermore, the concentration of 5-amino-2-naphthalenesulfonic acid is 0.05~0.15 mol / L.

[0010] Preferably, the additive is 3-aminobenzenesulfonic acid.

[0011] Furthermore, the concentration of 3-aminobenzenesulfonic acid is 0.05~0.20 mol / L.

[0012] Preferably, the acidic electrolyte is sulfuric acid.

[0013] Secondly, the present invention provides a method for preparing the electrolyte, wherein an acidic electrolyte, vanadium oxysulfate, and additives are dissolved in water to obtain the electrolyte.

[0014] Preferably, the method for preparing the electrolyte includes: dissolving an acidic electrolyte in water to obtain solution A; dissolving vanadium oxysulfate in solution A to obtain solution B; and dissolving an additive in solution B to obtain the electrolyte.

[0015] Thirdly, the present invention provides a vanadium redox flow battery, including a positive electrode electrolyte, wherein the positive electrode electrolyte is the electrolyte as described above.

[0016] Preferably, the vanadium redox flow battery has a coulombic efficiency of 94.8%~97.7%, an energy efficiency of 80.77%~86.07%, and a voltage efficiency of 85.2%~88.1%.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The electrolyte of this invention incorporates one of 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, and 3-aminopropanesulfonic acid as an additive. Firstly, the naphthalene ring in the 5-amino-2-naphthalenesulfonic acid molecule, the benzene ring in the 3-aminobenzenesulfonic acid molecule, and the chain structure of the 3-aminopropanesulfonic acid molecule can all provide steric hindrance, physically blocking and dispersing VO2. + Ions, thus extremely effectively inhibiting their aggregation and nucleation, further suppressing VO2. + Ions precipitate out at high temperatures. Secondly, all three additives of this invention contain amino groups, and the nitrogen atom in the amino group possesses a lone pair of electrons. This allows the additives to act as electron donors, interacting with electron-deficient VO2+. + Ions undergo strong coordination interactions to form stable coordinate bonds; this process is known as VO2. + The ions create a more stable solvation environment, and this coordination fundamentally alters VO2. + The chemical form and reactivity of the ions not only significantly improved its solubility limit but also directly inhibited the chemical reaction pathway of its conversion to V₂O₅. Furthermore, in a strongly acidic electrolyte, the additive ionizes to release negatively charged sulfonate ions (-SO₃²⁻). - Sulfonate ions react with positively charged VO2 through strong Coulomb attraction. + The ions are tightly bound together, and this binding effect can bind highly reactive VO2. + The ions are effectively captured and dispersed around the additive molecules, physically blocking VO2. + The proximity and aggregation of ions significantly raise the energy barrier for nucleation and precipitation of V₂O₅. Finally, 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, and 3-aminopropanesulfonic acid exhibit strong adsorption capacity on the carbon electrode surface (a common positive electrode in vanadium redox flow batteries). This significantly alters the electrode interface properties, making it difficult for water molecules to remain stable and accumulate on the hydrophobic electrode surface. This change in electrode interface properties leads to a localized reduction in the concentration of water molecules near the electrode, directly weakening the basis of the oxygen evolution reaction from the reactant concentration perspective, thereby improving electrochemical performance. Simultaneously, the adsorption behavior of the additives in this invention improves the ion migration environment near the electrode interface, allowing reactants to be replenished to the electrode surface more quickly and products to leave more quickly, thus reducing concentration polarization and improving electrochemical performance. Therefore, the additives 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, or 3-aminopropanesulfonic acid introduced in this invention can inhibit VO₂...+ The precipitation of ions at high temperatures effectively broadens the operating temperature range of vanadium redox flow batteries; and it also suppresses VO2. + While ion precipitation occurs, it not only does not reduce the electrochemical performance of the vanadium redox flow battery, but actually improves it. Therefore, the additives introduced into the electrolyte of this invention can increase VO2 while ensuring good electrochemical performance. + High temperature stability.

[0019] Furthermore, the electrolyte additive of the present invention preferably contains 5-amino-2-naphthalenesulfonic acid. Compared with 3-aminobenzenesulfonic acid or 3-aminopropanesulfonic acid, the naphthalene ring in the 5-amino-2-naphthalenesulfonic acid molecule has a stronger steric hindrance effect. Through stronger hydrophobic interaction and π-π stacking effect, it can better physically block and disperse VO2. + Ions, inhibiting VO2 + Ions precipitate out at high temperatures. Moreover, the 5-amino-2-naphthalenesulfonic acid molecule has a larger planar structure, resulting in stronger adsorption capacity on the carbon electrode surface, which is more conducive to changing the electrode interface properties and thus significantly improving electrochemical performance.

[0020] Furthermore, the electrolyte additive of the present invention preferably contains 3-aminobenzenesulfonic acid. Compared with 3-aminopropanesulfonic acid, the benzene ring in the 3-aminobenzenesulfonic acid molecule can provide a stronger steric hindrance effect, thus exhibiting better VO2 suppression. + The effect of ion precipitation at high temperature; at the same time, compared with 3-aminopropanesulfonic acid, 3-aminobenzenesulfonic acid molecules have a larger planar structure and a strong adsorption capacity on the carbon electrode surface. Therefore, compared with 3-aminopropanesulfonic acid, the all-vanadium redox flow battery based on the additive 3-aminobenzenesulfonic acid has better electrochemical performance. Attached Figure Description

[0021] Figure 1 This is an optical image of the electrolyte in Comparative Example 1 during high-temperature performance testing.

[0022] Figure 2 This is an optical image of the electrolyte of Example 1 during high-temperature performance testing. Detailed Implementation

[0023] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] In this invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0.05~0.25" indicates that all real numbers between "0.05~0.25" have been listed in this invention, and "0.05~0.25" is simply an abbreviation of these numerical combinations.

[0025] In this invention, unless otherwise stated, the various operation steps may be performed sequentially or not. Preferably, the operation steps in this invention are performed sequentially.

[0026] Unless otherwise stated, the technical and scientific terms used in this invention have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0027] The electrolyte provided by the present invention comprises: an acidic electrolyte, vanadium oxysulfate, an additive, and water, wherein the additive is 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, or 3-aminopropanesulfonic acid; wherein the concentration of the acidic electrolyte in the electrolyte is 3.0~3.5 mol / L, the concentration of vanadium oxysulfate is 1.7~2.0 mol / L, and the concentration of the additive is 0.05~0.25 mol / L.

[0028] In this invention, vanadium oxysulfate in the electrolyte dissociates into VO in water. 2+ and SO4 2- When the electrolyte is used as the positive electrode electrolyte in a vanadium redox flow battery, during the charging process, the VO in the electrolyte... 2+ Oxidized to VO2 + As the charging process continues, the temperature rises continuously, and VO2... + It is prone to hydrolysis-polymerization chain reactions, leading to the precipitation of precipitates. To suppress VO2... + To address the precipitation of ions at high temperatures, this invention introduces additives such as 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, or 3-aminopropanesulfonic acid into the electrolyte. All three additives can provide steric hindrance, physically blocking and dispersing VO2. + Ions, thereby effectively inhibiting their aggregation and nucleation, and further suppressing VO2. + The precipitation of ions. Furthermore, in strongly acidic electrolytes, the three additives can ionize to release negatively charged sulfonate ions (-SO32-). - Sulfonate ions will interact with positively charged VO2 through strong Coulomb attraction. + The ions are tightly bound together, and this binding effect can bind highly reactive VO2. + The ions are effectively captured and dispersed around the additive molecules, physically blocking VO2. +The proximity and aggregation of ions significantly raises the energy barrier for nucleation and precipitation of V₂O₅. Simultaneously, the additives 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, and 3-aminopropanesulfonic acid contain amino groups, and the nitrogen atom in the amino group possesses a lone pair of electrons. This allows the additives to act as electron donors, reacting with electron-deficient VO₂. + Ions undergo strong coordination interactions, forming stable coordinate bonds. This process is VO2. + The ions create a more stable solvation environment, and this coordination fundamentally alters VO2. + The chemical form and reactivity of the ions not only significantly improve their solubility limit but also directly inhibit the chemical reaction pathway of their conversion to V₂O₅. Therefore, the additives 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, or 3-aminopropanesulfonic acid introduced in this invention can inhibit VO₂ + The precipitation of ions at high temperatures effectively broadens the operating temperature range of vanadium redox flow batteries and extends their cycle life. Meanwhile, the research results of this invention show that the additive effectively suppresses VO2... + While ion precipitation occurs, it does not reduce the electrochemical performance of the vanadium redox flow battery; on the contrary, it improves the electrochemical performance of the vanadium redox flow battery.

[0029] In some preferred embodiments of the present invention, the additive is 5-amino-2-naphthalenesulfonic acid. The naphthalene ring in the 5-amino-2-naphthalenesulfonic acid molecule can provide a stronger steric hindrance effect, physically blocking and dispersing VO2 through strong hydrophobic interactions and π-π stacking effects. + Ions, thus extremely effectively inhibiting their aggregation and nucleation, thereby inhibiting VO2. + High-temperature precipitation of ions. The 5-amino-2-naphthalenesulfonic acid molecule has a larger planar structure and extremely strong adsorption capacity on the carbon electrode surface. This can significantly change the electrode interface properties, making it difficult for water molecules to exist stably and accumulate on the hydrophobic electrode surface. This change in electrode interface properties leads to a local reduction in the concentration of water molecules near the electrode, directly weakening the basis of the oxygen evolution reaction from the perspective of reactant concentration, thus improving electrochemical performance. At the same time, the adsorption behavior of 5-amino-2-naphthalenesulfonic acid can improve the ion migration environment near the electrode interface, allowing reactants to be replenished to the electrode surface more quickly and products to leave more quickly, thereby reducing concentration polarization and improving electrochemical performance.

[0030] In a further preferred embodiment of the present invention, the concentration of 5-amino-2-naphthalenesulfonic acid is 0.05~0.15 mol / L, for example, it can be 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, etc., more preferably 1.0 mol / L. If the concentration of 5-amino-2-naphthalenesulfonic acid is too low, it will not have a significant effect; however, if the concentration is too high, it will increase the viscosity of the electrolyte, thereby affecting the reaction kinetics of vanadium ions, leading to a decrease in the coulombic efficiency, voltage efficiency, and energy efficiency of the battery. Within the range of 0.05~0.15 mol / L specified in the present invention, 5-amino-2-naphthalenesulfonic acid can effectively suppress VO2. + High-temperature precipitation of ions can also improve the electrochemical performance of batteries.

[0031] In some preferred embodiments of the present invention, the additive is 3-aminobenzenesulfonic acid. Similar to 5-amino-2-naphthalenesulfonic acid, the benzene ring in the 3-aminobenzenesulfonic acid molecule can also provide a strong steric hindrance effect, physically blocking and dispersing VO2 through strong hydrophobic interactions and π-π stacking effects. + The adsorption of 3-aminobenzenesulfonic acid effectively inhibits the aggregation and nucleation of ions. Simultaneously, the large planar structure and strong adsorption capacity of 3-aminobenzenesulfonic acid on the carbon electrode surface significantly alter the electrode interface properties, making it difficult for water molecules to remain stable and accumulate on the electrode surface. This reduces the concentration of reactants near the electrode, weakens the oxygen evolution reaction, and improves electrochemical performance. The adsorption behavior of 3-aminobenzenesulfonic acid also improves the ion migration environment near the interface, allowing reactants to reach the electrode surface more quickly and products to leave more rapidly, thus reducing concentration polarization and improving electrochemical performance. However, because the naphthalene ring is larger than the benzene ring, 5-amino-2-naphthalenesulfonic acid is more effective than 3-aminobenzenesulfonic acid.

[0032] In a further preferred embodiment of the present invention, the concentration of 3-aminobenzenesulfonic acid is 0.05~0.20 mol / L, for example, it can be 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, etc., more preferably 1.5 mol / L. When the concentration of 3-aminobenzenesulfonic acid is too high, it will increase the viscosity of the electrolyte, thereby affecting the reaction kinetics of vanadium ions and adversely affecting the electrochemical performance. Therefore, the concentration of 3-aminobenzenesulfonic acid should preferably be controlled at 0.05~0.20 mol / L.

[0033] In some embodiments of the present invention, the additive is 3-aminopropanesulfonic acid; the concentration of 3-aminopropanesulfonic acid is 0.05~0.25 mol / L, for example, it can be 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, etc., more preferably 2.0 mol / L.

[0034] In some preferred embodiments of the present invention, the acidic electrolyte is sulfuric acid.

[0035] The method for preparing the electrolyte according to the present invention includes: dissolving an acidic electrolyte, vanadium oxysulfate and an additive in water to obtain the electrolyte.

[0036] In some preferred embodiments of the present invention, the method for preparing the electrolyte specifically includes: dissolving an acidic electrolyte in water to obtain solution A; dissolving vanadium oxysulfate in solution A to obtain solution B; and dissolving an additive in solution B to obtain the electrolyte.

[0037] The order in which the components are added to the electrolyte of the present invention does not affect the performance of the electrolyte. Therefore, the above electrolyte can also be prepared according to other order of addition, for example, first dissolving vanadium oxysulfate in water, then adding the acidic electrolyte, and then adding the additives.

[0038] Based on the electrolyte described above, the present invention provides an all-vanadium redox flow battery, including a positive electrode electrolyte, wherein the positive electrode electrolyte is the electrolyte described above.

[0039] In the vanadium redox flow battery of this invention, the additives 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, and 3-aminopropanesulfonic acid can effectively inhibit VO2. + Polymerization forms V2O5 precipitate, increasing VO2 + The high-temperature stability of vanadium redox flow batteries can be improved, the safe operating temperature range of vanadium redox flow batteries can be broadened, and the electrochemical performance of vanadium redox flow batteries can also be enhanced.

[0040] The vanadium redox flow battery of the present invention has a coulombic efficiency of 94.8%~97.7%, an energy efficiency of 80.77%~86.07%, and a voltage efficiency of 85.2%~88.1%.

[0041] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The electrolyte composition of each embodiment and comparative example is shown in Table 1.

[0042] Table 1 Electrolyte composition of Examples 1-18 and Comparative Examples 1-3

[0043]

[0044] Example 1

[0045] A method for preparing an electrolyte, comprising:

[0046] S1: Prepare c 硫酸=3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0047] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0048] S3: Weigh 1.116 g of 5-amino-2-naphthalenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2. Stir until completely dissolved.

[0049] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0050] Example 2

[0051] A method for preparing an electrolyte, comprising:

[0052] S1: Prepare c 硫酸 =3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0053] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0054] S3: Weigh 2.233 g of 5-amino-2-naphthalenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2. Stir until completely dissolved.

[0055] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0056] Example 3

[0057] A method for preparing an electrolyte, comprising:

[0058] S1: Prepare c 硫酸=3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade) and slowly pour it into a beaker containing high-purity water while stirring. Then dilute to 200 mL.

[0059] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0060] S3: Weigh 3.349 g of 5-amino-2-naphthalenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2. Stir until completely dissolved.

[0061] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0062] Example 4

[0063] A method for preparing an electrolyte, comprising:

[0064] S1: Prepare c 硫酸 =3.0 mol / L dilute sulfuric acid: Weigh 60.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0065] S2: Preparation of V(Ⅳ) solution: Weigh 39.95 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.0 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0066] S3: Weigh 2.233 g of 5-amino-2-naphthalenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2. Stir until completely dissolved.

[0067] S4: Dilute the solution obtained in S3 to 100 mL with 3.0 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0068] Example 5

[0069] A method for preparing an electrolyte, comprising:

[0070] S1: Prepare c 硫酸=3.5 mol / L dilute sulfuric acid: Weigh 70.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0071] S2: Preparation of V(Ⅳ) solution: Weigh 47.00 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.5 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0072] S3: Weigh 2.233 g of 5-amino-2-naphthalenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2. Stir until completely dissolved.

[0073] S4: Dilute the solution obtained in S3 to 100 mL with 3.5 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0074] Example 6

[0075] A method for preparing an electrolyte, comprising:

[0076] S1: Prepare c 硫酸 =3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0077] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0078] S3: Weigh 0.866 g of 3-aminobenzenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0079] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0080] Example 7

[0081] A method for preparing an electrolyte, comprising:

[0082] S1: Prepare c 硫酸=3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade) and slowly pour it into a beaker containing high-purity water while stirring. Then dilute to 200 mL.

[0083] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0084] S3: Weigh 1.732 g of 3-aminobenzenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0085] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0086] Example 8

[0087] A method for preparing an electrolyte, comprising:

[0088] S1: Prepare c 硫酸 =3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0089] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0090] S3: Weigh 2.598 g of 3-aminobenzenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0091] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0092] Example 9

[0093] A method for preparing an electrolyte, comprising:

[0094] S1: Prepare c 硫酸=3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0095] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0096] S3: Weigh 3.464 g of 3-aminobenzenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0097] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0098] Example 10

[0099] A method for preparing an electrolyte, comprising:

[0100] S1: Prepare c 硫酸 =3.0 mol / L dilute sulfuric acid: Weigh 60.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0101] S2: Preparation of V(Ⅳ) solution: Weigh 39.95 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.0 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0102] S3: Weigh 2.598 g of 3-aminobenzenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0103] S4: Dilute the solution obtained in S3 to 100 mL with 3.0 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0104] Example 11

[0105] A method for preparing an electrolyte, comprising:

[0106] S1: Prepare c 硫酸=3.5 mol / L dilute sulfuric acid: Weigh 70.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0107] S2: Preparation of V(Ⅳ) solution: Weigh 47.00 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.5 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0108] S3: Weigh 2.598 g of 3-aminobenzenesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0109] S4: Dilute the solution obtained in S3 to 100 mL with 3.5 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0110] Example 12

[0111] A method for preparing an electrolyte, comprising:

[0112] S1: Prepare c 硫酸 =3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0113] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0114] S3: Weigh 0.696 g of 3-aminopropanesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0115] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0116] Example 13

[0117] A method for preparing an electrolyte, comprising:

[0118] S1: Prepare c 硫酸=3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0119] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0120] S3: Weigh 1.392 g of 3-aminopropanesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0121] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0122] Example 14

[0123] A method for preparing an electrolyte, comprising:

[0124] S1: Prepare c 硫酸 =3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0125] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0126] S3: Weigh 2.088 g of 3-aminopropanesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0127] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0128] Example 15

[0129] A method for preparing an electrolyte, comprising:

[0130] S1: Prepare c 硫酸=3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0131] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0132] S3: Weigh 2.783g of 3-aminopropanesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0133] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0134] Example 16

[0135] A method for preparing an electrolyte, comprising:

[0136] S1: Prepare c 硫酸 =3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade) and slowly pour it into a beaker containing high-purity water while stirring. Then dilute to 200 mL.

[0137] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0138] S3: Weigh 3.479 g of 3-aminopropanesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0139] S4: Dilute the solution obtained in S3 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0140] Example 17

[0141] A method for preparing an electrolyte, comprising:

[0142] S1: Prepare c 硫酸=3.0 mol / L dilute sulfuric acid: Weigh 60.00 g of 98wt% concentrated sulfuric acid (analytical grade) and slowly pour it into a beaker containing high-purity water while stirring. Then dilute to 200 mL.

[0143] S2: Preparation of V(Ⅳ) solution: Weigh 39.95 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.0 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0144] S3: Weigh 2.783 g of 3-aminopropanesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0145] S4: Dilute the solution obtained in S3 to 100 mL with 3.0 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0146] Example 18

[0147] A method for preparing an electrolyte, comprising:

[0148] S1: Prepare c 硫酸 =3.5 mol / L dilute sulfuric acid: Weigh 70.00 g of 98wt% concentrated sulfuric acid (analytical grade) and slowly pour it into a beaker containing high-purity water while stirring. Then dilute to 200 mL.

[0149] S2: Preparation of V(Ⅳ) solution: Weigh 47.00 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.5 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0150] S3: Weigh 2.783 g of 3-aminopropanesulfonic acid and add it to the V(Ⅳ) solution prepared in S2, and stir until completely dissolved.

[0151] S4: Dilute the solution obtained in S3 to 100 mL with 3.5 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0152] Comparative Example 1

[0153] A method for preparing an electrolyte, comprising:

[0154] S1: Prepare c 硫酸=3.0 mol / L dilute sulfuric acid: Weigh 60.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0155] S2: Preparation of V(Ⅳ) solution: Weigh 39.95 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.0 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0156] S3: Dilute the solution obtained in S2 to 100 mL with 3.0 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0157] Comparative Example 2

[0158] A method for preparing an electrolyte, comprising:

[0159] S1: Prepare c 硫酸 =3.2 mol / L dilute sulfuric acid: Weigh 64.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0160] S2: Preparation of V(Ⅳ) solution: Weigh 42.30 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸 =3.2 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0161] S3: Dilute the solution obtained in S2 to 100 mL with 3.2 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0162] Comparative Example 3

[0163] A method for preparing an electrolyte, comprising:

[0164] S1: Prepare c 硫酸 =3.5 mol / L dilute sulfuric acid: Weigh 70.00 g of 98wt% concentrated sulfuric acid (analytical grade), slowly pour it into a beaker containing high-purity water while stirring, and then dilute to 200 mL.

[0165] S2: Preparation of V(Ⅳ) solution: Weigh 47.00 g of vanadium oxysulfate hydrate VOSO4·4H2O using an analytical balance, and add 50 mL of c 硫酸=3.5 mol / L dilute sulfuric acid was added while stirring until the vanadium oxysulfate hydrate was completely dissolved, resulting in solution V(Ⅳ).

[0166] S3: Dilute the solution obtained in S2 to 100 mL with 3.5 mol / L dilute sulfuric acid to obtain the electrolyte, and let it stand for later use.

[0167] Negative Electrolyte Preparation: 100 mL of a 1.8 mol / L V(Ⅳ) solution (prepared according to the electrolyte preparation method of Comparative Example 2) was placed on both the positive and negative electrode sides of the vanadium redox flow cell system. The sulfuric acid concentration was 3.2 mol / L. Charging was performed at a constant voltage of 1.55 V. When the open-circuit voltage reached 1.45 V (charging capacity of 5.7 Ah), V(IV) in the negative electrode electrolyte was reduced to V(III), with the concentration remaining at 1.8 mol / L. This negative electrode electrolyte was used as the negative electrode electrolyte for subsequent assembly of the vanadium redox flow cell.

[0168] 1. The electrolytes prepared in Examples 1-18 and Comparative Examples 1-3 were subjected to high-temperature performance tests.

[0169] The electrolytes prepared in Examples 1-18 and Comparative Examples 1-3 were used as positive electrode electrolytes and assembled with the aforementioned negative electrode electrolytes to form an all-vanadium redox flow cell. High-temperature performance tests of the electrolytes were then conducted. The experimental conditions were: commercially available carbon felt (i.e., carbon electrode) with an electrode area of ​​10 cm². 2 The diaphragm is a Nafion membrane, and the charge / discharge current density is 80 mA / cm². 2 The charging time was 6 hours, the discharge cutoff voltage was 1.0 V, the positive and negative electrolytes were both 100 mL, the test environment temperature was 50.0℃, and the performance tests of the batteries corresponding to the electrolytes in each example and comparative example were conducted under the same conditions.

[0170] Test results show that the electrolytes prepared in comparative examples 1-3 contain VO2. + Ions showed obvious precipitation and blockage of the pipeline. Figure 1 The image shows an optical image of the electrolyte in Comparative Example 1 during high-temperature performance testing, revealing the formation of a precipitate. This is because at higher ambient temperatures, the VO2 in the positive electrode electrolyte... + Ions undergo hydrolysis, and the intermediates from hydrolysis polymerize to form V₂O₅ precipitate. This V₂O₅ precipitate clogs the flow channels, contaminates the membrane, and affects the electrodes, leading to irreversible degradation of battery performance. The electrolytes prepared in Examples 1-18 contain VO₂... + No ions were precipitated. Figure 2The image shows an optical image of the electrolyte from Example 1 during high-temperature performance testing. It can be seen that no precipitation formed. This is because the naphthalene ring of 5-amino-2-naphthalenesulfonic acid and the benzene ring of 3-aminobenzenesulfonic acid can provide significant steric hindrance, physically blocking and dispersing VO2. + 3-Aminopropanesulfonic acid is a chain-like, flexible small molecule that, through its chain structure and flexibility, can effectively inhibit the aggregation and nucleation of VO2+ ions; + Ions encapsulation, this mechanism helps prevent VO2. + The transformation of the initial hydration structure of ions into precipitates is also effective. Furthermore, the "amino" group in the additive acts as a coordination site with VO2. + Forming coordinate bonds can effectively block multiple VO2 molecules. + Ions approach each other and aggregate to form V₂O₅ precipitate. The "sulfonic acid group" can react with VO₂. + A strong electrostatic attraction is generated, which also prevents the formation of V2O5 precipitation. All of these mechanisms can increase VO2... + The high-temperature stability of ions expands the safe operating temperature range of vanadium redox flow batteries.

[0171] 2. Test the battery performance.

[0172] The electrolytes prepared in Examples 1-18 and Comparative Examples 1-3 were used as positive electrode electrolytes and assembled with the aforementioned negative electrode electrolytes to form vanadium redox flow single cells. Performance testing of the vanadium redox flow battery was then conducted. The experimental conditions were: commercially available carbon felt electrodes with an electrode area of ​​10 cm². 2 The diaphragm is a Nafion membrane, and the charge / discharge current density is 80 mA / cm². 2 The charging time was 6 hours, the discharge cutoff voltage was 1.0 V, the positive and negative electrolytes were both 100 mL, the test environment temperature was room temperature, and the performance tests of the batteries corresponding to the electrolytes in each example and comparative example were conducted under the same conditions. The test results are shown in Table 2.

[0173] Table 2 Performance test results of all-vanadium redox flow batteries using electrolytes from Examples 1-18 and Comparative Examples 1-3

[0174]

[0175] Table 1 compares the composition of key components in Examples 1-18 and Comparative Examples 1-3; Table 2 compares the performance test results of the vanadium redox flow batteries prepared with the electrolytes of Examples 1-18 and Comparative Examples 1-3. As shown in Table 2, the coulombic efficiency of the vanadium redox flow battery prepared with the electrolyte of the present invention is 94.8%~97.7%; the energy efficiency is 80.77%~86.07%; and the voltage efficiency is 85.2%~88.1%.

[0176] Comparing Examples 1-5 with Comparative Examples 1-3, it can be seen that adding different concentrations of 5-amino-2-naphthalenesulfonic acid to the positive electrode electrolyte of the vanadium redox flow battery results in better electrochemical performance. The coulombic efficiency, voltage efficiency, and energy efficiency of the vanadium redox flow batteries corresponding to Examples 1-5 are significantly better than those corresponding to Comparative Examples 1-3, indicating that 5-amino-2-naphthalenesulfonic acid can not only suppress VO2... + The precipitation of ions at high temperatures can also improve the electrochemical performance of vanadium redox flow batteries.

[0177] Comparing Examples 1-3, it can be seen that Example 2, with a 5-amino-2-naphthalenesulfonic acid concentration of 0.10 mol / L, exhibits better electrochemical performance, indicating that appropriately increasing the concentration of 5-amino-2-naphthalenesulfonic acid has a significant effect on improving electrochemical performance. This is because the 5-amino-2-naphthalenesulfonic acid molecule has a large planar structure and extremely strong adsorption capacity on the carbon electrode surface. This can significantly change the electrode interface properties. Water molecules are difficult to exist stably and accumulate on the hydrophobic electrode surface. This change in interface properties leads to a local decrease in the concentration of water molecules near the electrode, directly weakening the basis of the oxygen evolution reaction from the reactant concentration, thus improving electrochemical performance. The adsorption behavior also improves the ion migration environment near the electrode interface, allowing reactants to be replenished to the electrode surface more quickly and products to leave more quickly, thereby reducing concentration polarization and improving electrochemical performance. Therefore, coulombic efficiency, voltage efficiency, and energy efficiency are all improved. When the added concentration is too high, the viscosity of the electrolyte increases, thereby affecting the reaction kinetics of vanadium ions, leading to a downward trend in coulombic efficiency, voltage efficiency, and energy efficiency.

[0178] Comparing Examples 4-5 with Example 2, it can be seen that increasing the vanadium ion concentration can increase the active substances in the electrolyte, thereby improving the electrochemical performance to a certain extent.

[0179] Comparing Examples 6-11 with Comparative Examples 1-3, it can be seen that adding different concentrations of 3-aminobenzenesulfonic acid to the positive electrode electrolyte of the vanadium redox flow battery results in better electrochemical performance. The coulombic efficiency, voltage efficiency, and energy efficiency of the vanadium redox flow batteries corresponding to Examples 6-11 are significantly better than those corresponding to Comparative Examples 1-3, indicating that 3-aminobenzenesulfonic acid can not only suppress VO2... + The precipitation of ions at high temperatures can also improve the electrochemical performance of vanadium redox flow batteries.

[0180] Comparing Examples 6-9, it can be seen that Example 8, with a 3-aminobenzenesulfonic acid concentration of 0.15 mol / L, exhibits better electrochemical performance, indicating that appropriately increasing the concentration of 3-aminobenzenesulfonic acid has a significant effect on improving electrochemical performance. This is because the 3-aminobenzenesulfonic acid molecule has a large planar structure and extremely strong adsorption capacity on the carbon electrode surface. This can significantly change the electrode interface properties. Water molecules are difficult to exist stably and accumulate on the hydrophobic electrode surface. This change in interface properties leads to a local decrease in the concentration of water molecules near the electrode, directly weakening the basis of the oxygen evolution reaction from the reactant concentration, thus improving electrochemical performance. The adsorption behavior also improves the ion migration environment near the interface, allowing reactants to be replenished to the electrode surface more quickly and products to leave more quickly, thereby reducing concentration polarization and improving electrochemical performance. Therefore, coulombic efficiency, voltage efficiency, and energy efficiency are all improved. When the added concentration is too high, the viscosity of the electrolyte increases, thereby affecting the reaction kinetics of vanadium ions, leading to a downward trend in coulombic efficiency, voltage efficiency, and energy efficiency.

[0181] Comparing Examples 12-18 with Comparative Examples 1-3, it can be seen that adding different concentrations of 3-aminopropanesulfonic acid to the positive electrode electrolyte of the vanadium redox flow battery results in better electrochemical performance. The coulombic efficiency, voltage efficiency, and energy efficiency of the vanadium redox flow batteries corresponding to Examples 12-18 are all superior to those of the vanadium redox flow batteries corresponding to Comparative Examples 1-3, indicating that 3-aminopropanesulfonic acid can not only suppress VO2... + The precipitation of ions at high temperatures can also improve the electrochemical performance of the battery. This is because there are a large number of different types of active sites on the surface of the carbon electrode. Some of these high-energy, disordered defect sites are sites where side reactions (such as oxygen evolution and carbon corrosion) occur. 3-Aminopropanesulfonic acid can preferentially adsorb onto these highest-energy defect sites, fundamentally inhibiting the occurrence of side reactions and thus improving electrochemical performance.

[0182] Comparing Examples 12-16, it can be seen that Example 15, with a 3-aminopropanesulfonic acid concentration of 0.20 mol / L, exhibits better electrochemical performance, indicating that appropriately increasing the concentration of 3-aminopropanesulfonic acid has a significant effect on improving electrochemical performance. However, when the concentration of 3-aminopropanesulfonic acid is too high, it will increase the viscosity of the electrolyte, thereby affecting the reaction kinetics of vanadium ions and leading to a decrease in coulombic efficiency, voltage efficiency, and energy efficiency.

[0183] Comparing Examples 2, 8, and 15, it can be seen that, at their respective optimal concentrations, the vanadium redox flow battery assembled with the electrolyte containing 5-amino-2-naphthalenesulfonic acid in Example 2 exhibits the best performance, followed by 3-aminobenzenesulfonic acid, and lastly 3-aminopropanesulfonic acid. This is because, compared to 3-aminobenzenesulfonic acid and 3-aminopropanesulfonic acid, the naphthalene ring in 5-amino-2-naphthalenesulfonic acid has a stronger steric hindrance effect, which can better suppress VO2. + Ions precipitate out at high temperatures; moreover, 5-amino-2-naphthalenesulfonic acid molecules have a larger planar structure, which makes them more adsorbed on the carbon electrode surface and more conducive to changing the electrode interface properties, resulting in a more significant improvement in electrochemical performance.

[0184] In summary, this invention adds one of 3-aminobenzenesulfonic acid, 3-aminopropanesulfonic acid, and 5-amino-2-naphthalenesulfonic acid to the positive electrode electrolyte of a vanadium redox flow battery. The rings (benzene ring and naphthalene ring) in the molecules of 3-aminobenzenesulfonic acid and 5-amino-2-naphthalenesulfonic acid, and the chain structure in the 3-aminopropanesulfonic acid molecule, can provide a steric hindrance effect, physically blocking and dispersing VO2. + These ions effectively inhibit their aggregation and nucleation; simultaneously, the sulfonic acid groups in each molecule can react with VO2. + The ions generate a strong electrostatic attraction, while the "amino" group acts as a coordination site to form a coordinate bond with V (V), effectively preventing multiple VO2 groups from being attracted. + Ions approach each other and aggregate to form V₂O₅ precipitate. Thus, the additive of this invention increases VO₂. + The high-temperature stability of ions broadens the safe operating temperature range of vanadium redox flow batteries. Furthermore, the planar structures of 3-aminobenzenesulfonic acid and 5-amino-2-naphthalenesulfonic acid molecules, or the chain structure of 3-aminopropanesulfonic acid molecules, adsorb onto the carbon electrode surface. This significantly alters the electrode interface properties, thereby suppressing side reactions and polarization, and improving coulombic efficiency, voltage efficiency, and energy efficiency.

[0185] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolyte, characterized in that, include: The electrolyte comprises an acidic electrolyte, vanadium oxysulfate, an additive, and water, wherein the additive is 5-amino-2-naphthalenesulfonic acid, 3-aminobenzenesulfonic acid, or 3-aminopropanesulfonic acid; in the electrolyte, the concentration of the acidic electrolyte is 3.0~3.5 mol / L, the concentration of the vanadium oxysulfate is 1.7~2.0 mol / L, and the concentration of the additive is 0.05~0.25 mol / L.

2. The electrolyte according to claim 1, characterized in that, The additive is 5-amino-2-naphthalenesulfonic acid.

3. The electrolyte according to claim 2, characterized in that, The concentration of 5-amino-2-naphthalenesulfonic acid is 0.05~0.15 mol / L.

4. The electrolyte according to claim 1, characterized in that, The additive is 3-aminobenzenesulfonic acid.

5. The electrolyte according to claim 4, characterized in that, The concentration of 3-aminobenzenesulfonic acid is 0.05~0.20 mol / L.

6. The electrolyte according to claim 1, characterized in that, The acidic electrolyte is sulfuric acid.

7. The method for preparing the electrolyte according to any one of claims 1 to 6, characterized in that, The electrolyte is obtained by dissolving an acidic electrolyte, vanadium oxysulfate, and additives in water.

8. The method for preparing the electrolyte according to claim 7, characterized in that, include: Acidic electrolytes are dissolved in water to obtain solution A; Vanadium oxysulfate is dissolved in solution A to obtain solution B; The additive is dissolved in solution B to obtain the electrolyte.

9. A vanadium redox flow battery, characterized in that, It includes a positive electrode electrolyte, wherein the positive electrode electrolyte is the electrolyte according to any one of claims 1 to 6.

10. The all-vanadium redox flow battery according to claim 9, characterized in that, The vanadium redox flow battery has a coulombic efficiency of 94.8%~97.7%, an energy efficiency of 80.77%~86.07%, and a voltage efficiency of 85.2%~88.1%.

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