A vanadium redox flow battery precursor, a vanadium redox flow battery and its preparation method

Abstract

This invention belongs to the field of vanadium redox flow batteries, specifically relating to a vanadium redox flow battery precursor, a vanadium redox flow battery, and a method for preparing the same. The vanadium redox flow battery precursor of this invention includes a positive electrode electrolyte precursor and a negative electrode electrolyte precursor; the positive electrode electrolyte precursor includes vanadium ions, an inorganic acid, a positive electrode side reaction inhibitor precursor, and a solvent; wherein the positive electrode side reaction inhibitor precursor is aniline; the inorganic acid includes hydrochloric acid; the negative electrode electrolyte precursor includes vanadium ions, an inorganic acid, a negative electrode side reaction inhibitor precursor, and a solvent; wherein the negative electrode side reaction inhibitor precursor is a metal compound; the metal compound is selected from one or more of tin compounds, bismuth compounds, and antimony compounds; the inorganic acid includes hydrochloric acid.

Description

Technical Field

[0001] This invention belongs to the field of vanadium redox flow batteries, specifically, it relates to a vanadium redox flow battery precursor, a vanadium redox flow battery, and a method for preparing the same. Background Technology

[0002] Vanadium redox flow batteries are a large-scale energy storage technology based on the redox reaction of vanadium ions. They utilize the reversible conversion of vanadium ions in different valence states within the electrolyte to achieve energy storage and release. Vanadium batteries offer advantages such as ultra-long cycle life, high safety, independently adjustable capacity and power, and environmental friendliness. With technological advancements and large-scale applications, vanadium redox flow batteries are expected to become a key solution in the field of long-term energy storage.

[0003] The electrolyte is the core of the energy storage in a vanadium redox flow battery, composed of vanadium ions in different valence states dissolved in an acidic solution (such as sulfuric acid or a sulfuric acid-hydrochloric acid mixture). The sulfuric acid-hydrochloric acid mixture electrolyte (H₂SO₄ + HCl) is a high-performance electrolyte system in vanadium redox flow batteries. Compared to sulfuric acid-based electrolytes, the sulfuric acid-hydrochloric acid mixture combines the advantages of both sulfuric and hydrochloric acids, significantly improving vanadium ion solubility and electrolyte stability, and has become one of the important pathways to overcome the performance bottlenecks of vanadium redox flow batteries.

[0004] However, when using a sulfuric acid-hydrochloric acid mixed electrolyte in a vanadium redox flow battery, the gas evolution side reaction at both the positive and negative electrodes is a key challenge. During charging, as the potential changes, the Cl- on the positive electrode side of the vanadium battery... - It will be oxidized to Cl2 and precipitated, H on the negative electrode side + It will be reduced to H2 and precipitated. The side reactions at the positive and negative electrodes can cause an imbalance in the valence state of vanadium ions, resulting in a loss of battery capacity. The Cl2 generated on the positive electrode side can corrode electrode materials and damage key materials such as the ion-exchange membrane, thus affecting the lifespan of the vanadium battery. Furthermore, the mixing of Cl2 and H2 produced by the side reactions may create an explosive environment.

[0005] Therefore, there is an urgent need to develop an all-vanadium redox flow battery that can effectively reduce side reactions of gas evolution at the positive and negative electrodes, thereby improving battery performance and safety. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a positive electrolyte precursor containing a positive electrode side reaction inhibitor precursor and a negative electrolyte precursor containing a negative electrode side reaction inhibitor precursor, forming a side reaction inhibitor combination. As the first charging cycle of the vanadium redox flow battery precursor proceeds, the two side reaction inhibitor precursors generate the side reaction inhibitor. This invention, through the synergistic effect of the side reaction inhibitor combination, simultaneously suppresses the chlorine evolution and hydrogen evolution side reactions in hydrochloric acid-based vanadium redox flow batteries, contributing to improved performance and enhanced safety of the vanadium redox flow battery.

[0007] Specifically, the present invention provides a vanadium redox flow battery precursor, comprising a positive electrode electrolyte precursor and a negative electrode electrolyte precursor; the positive electrode electrolyte precursor comprises vanadium ions, an inorganic acid, a positive electrode side reaction inhibitor precursor, and a solvent; wherein the positive electrode side reaction inhibitor precursor is aniline; the inorganic acid comprises hydrochloric acid; the negative electrode electrolyte precursor comprises vanadium ions, an inorganic acid, a negative electrode side reaction inhibitor precursor, and a solvent; wherein the negative electrode side reaction inhibitor precursor is a metal compound; the metal compound is selected from one or more of tin compounds, bismuth compounds, and antimony compounds; the inorganic acid comprises hydrochloric acid.

[0008] In one or more embodiments, the concentration of the positive electrode side reaction inhibitor precursor in the positive electrode electrolyte precursor is 0.05~0.2 mol / L.

[0009] In one or more embodiments, the concentration of the inorganic acid in the positive electrode electrolyte precursor is 6.5~7.5 mol / L.

[0010] In one or more embodiments, the concentration of hydrochloric acid in the positive electrode electrolyte precursor is 4.5~5.0 mol / L.

[0011] In one or more embodiments, the inorganic acid in the positive electrode electrolyte precursor further comprises sulfuric acid.

[0012] In one or more embodiments, the solvent in the positive electrode electrolyte precursor is water.

[0013] In one or more embodiments, the concentration of the negative electrode side reaction inhibitor precursor in the negative electrode electrolyte precursor is 0.02~0.08 mol / L.

[0014] In one or more embodiments, the concentration of the inorganic acid in the negative electrode electrolyte precursor is 6.5~7.5 mol / L.

[0015] In one or more embodiments, the concentration of hydrochloric acid in the negative electrode electrolyte precursor is 4.5~5.0 mol / L.

[0016] In one or more embodiments, the inorganic acid in the negative electrode electrolyte precursor further comprises sulfuric acid.

[0017] In one or more embodiments, the solvent in the negative electrode electrolyte precursor is water.

[0018] In one or more embodiments, the metal compound is selected from one or more metal chlorides.

[0019] In one or more embodiments, the vanadium redox flow battery precursor further includes a positive electrode substrate, a negative electrode substrate, and a separator.

[0020] In one or more embodiments, the positive electrode substrate is a carbon-based electrode; the carbon-based electrode is carbon felt, carbon cloth, or carbon paper.

[0021] In one or more embodiments, the negative electrode substrate is a carbon-based electrode; the carbon-based electrode is carbon felt, carbon cloth, or carbon paper.

[0022] The present invention provides a vanadium redox flow battery, the vanadium redox flow battery comprising a positive electrode, a negative electrode, a positive electrolyte and a negative electrolyte, the surface of the positive electrode comprising polyaniline as a positive electrode side reaction inhibitor, and the surface of the negative electrode comprising metal nanoparticles as a negative electrode side reaction inhibitor, wherein the metal in the metal nanoparticles is selected from one or more of tin, bismuth and antimony.

[0023] In one or more embodiments, the loading of the positive electrode side reaction inhibitor in the positive electrode is 6.60 × 10⁻⁶. -3 ~3.30×10 -2 mg / cm 3 .

[0024] In one or more embodiments, the loading of the negative electrode side reaction inhibitor in the negative electrode is 4.78 × 10⁻⁶. -3 ~1.80×10 -2 mg / cm 3 .

[0025] This invention provides a method for preparing the vanadium redox flow battery of the present invention. The method includes constant current charging of the vanadium redox flow battery precursor of the present invention to obtain the vanadium redox flow battery. During the constant current charging process, the positive electrode electrolyte precursor is converted into a positive electrode electrolyte, and the negative electrode electrolyte precursor is converted into a negative electrode electrolyte.

[0026] In one or more embodiments, the charging voltage during constant current charging is 1~1.55V.

[0027] In one or more embodiments, the constant current charging is performed with a current density of 5~20 mA / cm². 2 .

[0028] Compared with the prior art, the present invention has the following beneficial technical effects:

[0029] (1) The method of adding the precursor of the side reaction inhibitor of the present invention is simple; and as the first charging program of the vanadium redox flow battery precursor is carried out, the positive electrode side forms a positive electrode side reaction inhibitor that inhibits the chlorine evolution side reaction on the surface of the positive electrode fiber through polymerization reaction during the charging process; the negative electrode side also forms a negative electrode side reaction inhibitor that inhibits the hydrogen evolution reaction on the surface of the negative electrode fiber through reduction reaction during the charging process. The two side reaction inhibitors are formed along with the charging process of the battery, and the preparation process is simple.

[0030] (2) The side reaction inhibitor prepared by the electrodeposition method of the present invention has good stability and will not affect the service life of the electrode;

[0031] (3) The present invention suppresses the chlorine evolution and hydrogen evolution side reactions of the hydrochloric acid-based vanadium redox flow battery through the synergistic effect of the combination of side reaction inhibitors, which helps to improve the performance of the vanadium redox flow battery and ensure the safety of the hydrochloric acid-based vanadium redox flow battery. Detailed Implementation

[0032] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0033] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0034] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0035] In this document, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0036] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0037] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0038] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0039] The vanadium redox flow battery precursor provided by this invention includes a positive electrode electrolyte precursor and a negative electrode electrolyte precursor; the positive electrode electrolyte precursor includes vanadium ions, an inorganic acid, a positive electrode side reaction inhibitor precursor, and a solvent; the inorganic acid in the positive electrode electrolyte precursor includes hydrochloric acid; the negative electrode electrolyte precursor includes vanadium ions, an inorganic acid, a negative electrode side reaction inhibitor precursor, and a solvent; the inorganic acid in the negative electrode electrolyte precursor includes hydrochloric acid.

[0040] In this invention, the precursor for the positive electrode side reaction inhibitor is aniline (C6H7N). Under constant current, aniline is continuously oxidized on the surface of the positive electrode to generate free radical cations, which then gradually polymerize into polyaniline, the positive electrode side reaction inhibitor, through a coupling reaction.

[0041] In this invention, the precursor of the negative electrode side reaction inhibitor is a metal compound; the metal compound can be one or more selected from tin compounds, bismuth compounds, and antimony compounds. In this invention, the metal compound can be one or more selected from metal chlorides. Metal chlorides have good solubility in water and do not introduce new anions, thus avoiding any impact on the electrolyte performance. In this invention, the metal ions of the metal compound gain electrons on the surface of the negative electrode under the action of a constant current, and are gradually reduced to metal nanoparticles, which are the negative electrode side reaction inhibitors, through a reduction reaction.

[0042] In the positive electrode electrolyte precursor of this invention, the concentration of the positive electrode side reaction inhibitor precursor is 0.05~0.2 mol / L, for example, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, and 0.2 mol / L. In this invention, excessive addition of the positive electrode side reaction inhibitor precursor can negatively impact performance. Controlling the content of the positive electrode side reaction inhibitor precursor within the above-mentioned range is beneficial for reducing positive electrode side reactions and improving the energy efficiency of the vanadium redox flow battery. In the negative electrode electrolyte precursor of this invention, the concentration of the negative electrode side reaction inhibitor precursor is 0.02~0.08 mol / L, for example, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, and 0.07 mol / L. In this invention, adding too much of the negative electrode side reaction inhibitor precursor can negatively affect performance. This invention controls the content of the negative electrode side reaction inhibitor precursor within the above-mentioned range, which is beneficial to reduce the side reactions of the negative electrode and improve the energy efficiency of the vanadium redox flow battery.

[0043] In the cathode electrolyte precursor of this invention, the vanadium ion can have a valence state of +3.5. The concentration of vanadium ions in the cathode electrolyte precursor of this invention can be 1.60~1.75 mol / L, for example 1.60 mol / L, 1.62 mol / L, 1.64 mol / L, 1.68 mol / L, 1.70 mol / L, 1.72 mol / L, and 1.75 mol / L. The concentration of inorganic acid in the cathode electrolyte precursor of this invention can be 6.5~7.5 mol / L, for example 6.5 mol / L, 6.6 mol / L, 6.7 mol / L, 6.8 mol / L, 6.9 mol / L, 7.0 mol / L, 7.1 mol / L, 7.2 mol / L, 7.3 mol / L, 7.4 mol / L, and 7.5 mol / L. In the positive electrode electrolyte precursor of this invention, the concentration of hydrochloric acid can be 4.5~5.0 mol / L, for example 4.5 mol / L, 4.6 mol / L, 4.7 mol / L, 4.8 mol / L, 4.9 mol / L, or 5.0 mol / L. The inorganic acid in the positive electrode electrolyte precursor of this invention may also include sulfuric acid. The solvent in the positive electrode electrolyte precursor of this invention can be water.

[0044] In the negative electrode electrolyte precursor of this invention, the vanadium ion can have a valence state of +3.5. The concentration of vanadium ions in the negative electrode electrolyte precursor of this invention can be 1.60~1.75 mol / L, for example 1.60 mol / L, 1.62 mol / L, 1.64 mol / L, 1.68 mol / L, 1.70 mol / L, 1.72 mol / L, and 1.75 mol / L. The concentration of inorganic acid in the negative electrode electrolyte precursor of this invention can be 6.5~7.5 mol / L, for example 6.5 mol / L, 6.6 mol / L, 6.7 mol / L, 6.8 mol / L, 6.9 mol / L, 7.0 mol / L, 7.1 mol / L, 7.2 mol / L, 7.3 mol / L, 7.4 mol / L, and 7.5 mol / L. In the negative electrode electrolyte precursor of this invention, the concentration of hydrochloric acid can be 4.5~5.0 mol / L, for example 4.5 mol / L, 4.6 mol / L, 4.7 mol / L, 4.8 mol / L, 4.9 mol / L, or 5.0 mol / L. The inorganic acid in the negative electrode electrolyte precursor of this invention may also include sulfuric acid. The solvent in the negative electrode electrolyte precursor of this invention can be water.

[0045] This invention provides a method for preparing a positive electrode electrolyte precursor, the method comprising directly adding a positive electrode side reaction inhibitor precursor to a positive electrode electrolyte matrix to obtain the positive electrode electrolyte precursor. This invention also provides a method for preparing a negative electrode electrolyte precursor, the method comprising directly adding a negative electrode side reaction inhibitor precursor to a negative electrode electrolyte matrix to obtain the negative electrode electrolyte precursor.

[0046] This invention provides a method for preparing the positive electrode electrolyte precursor of this invention, the method comprising directly adding a positive electrode side reaction inhibitor precursor solution to a positive electrode electrolyte matrix to obtain the positive electrode electrolyte precursor. This invention also provides a method for preparing the negative electrode electrolyte precursor of this invention, the method comprising directly adding a negative electrode side reaction inhibitor precursor solution to a negative electrode electrolyte matrix to obtain the negative electrode electrolyte precursor.

[0047] In this invention, the positive electrode side reaction inhibitor precursor solution comprises a positive electrode side reaction inhibitor precursor, an inorganic acid, and a solvent, wherein the inorganic acid includes hydrochloric acid. In this invention, the concentration of the positive electrode side reaction inhibitor precursor in the positive electrode side reaction inhibitor precursor solution can be 0.8~1.5 mol / L, for example, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, or 1.5 mol / L. In this invention, the solvent in the positive electrode side reaction inhibitor precursor solution can be water. In this invention, the concentration of the inorganic acid in the positive electrode side reaction inhibitor precursor solution can be 0.5~1.0 mol / L, for example, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1.0 mol / L. In the precursor solution of the positive electrode side reaction inhibitor of the present invention, the concentration of hydrochloric acid is 0.5~1.0 mol / L, for example 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, and 1.0 mol / L. The inorganic acid in the precursor solution of the positive electrode side reaction inhibitor of the present invention may also include sulfuric acid.

[0048] In this invention, the negative electrode side reaction inhibitor precursor solution comprises a negative electrode side reaction inhibitor precursor, an inorganic acid, and a solvent, wherein the inorganic acid comprises hydrochloric acid. In this invention, the concentration of the negative electrode side reaction inhibitor precursor in the negative electrode side reaction inhibitor precursor solution is 0.5~1.5 mol / L, for example, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, or 1.5 mol / L. In this invention, the solvent in the negative electrode side reaction inhibitor precursor solution can be water. In this invention, the concentration of the inorganic acid in the negative electrode side reaction inhibitor precursor solution can be 0.5~1.0 mol / L, for example, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1.0 mol / L. In the precursor solution of the negative electrode side reaction inhibitor of the present invention, the concentration of hydrochloric acid can be 0.5~1.0 mol / L, for example 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, or 1.0 mol / L. The inorganic acid in the precursor solution of the negative electrode side reaction inhibitor of the present invention may also include sulfuric acid.

[0049] In this invention, a positive electrode side reaction inhibitor precursor solution can be obtained by dissolving the positive electrode side reaction inhibitor precursor in an acidic solution; in this invention, a negative electrode side reaction inhibitor precursor solution can be obtained by dissolving the negative electrode side reaction inhibitor precursor in an acidic solution.

[0050] In this invention, the positive electrode electrolyte matrix comprises vanadium ions, an inorganic acid, and a solvent, wherein the inorganic acid includes hydrochloric acid. In the positive electrode electrolyte matrix of this invention, the solvent is water. The inorganic acid in the positive electrode electrolyte matrix of this invention may also include sulfuric acid.

[0051] In this invention, the negative electrode electrolyte matrix comprises vanadium ions, an inorganic acid, and a solvent, wherein the inorganic acid includes hydrochloric acid. In the negative electrode electrolyte matrix of this invention, the solvent is water. The inorganic acid in the negative electrode electrolyte matrix of this invention may also include sulfuric acid.

[0052] The vanadium redox flow battery precursor of the present invention further includes a positive electrode substrate, a negative electrode substrate, and a separator. In this invention, the positive electrode substrate can be a carbon-based electrode; the carbon-based electrode can be carbon felt, carbon cloth, or carbon paper. In this invention, the negative electrode substrate can be a carbon-based electrode; the carbon-based electrode can be carbon felt, carbon cloth, or carbon paper.

[0053] The vanadium redox flow battery provided by the present invention includes a positive electrode, a negative electrode, a positive electrolyte, and a negative electrolyte.

[0054] In this invention, the surface of the positive electrode includes polyaniline, which acts as an inhibitor of the positive electrode side reaction. The mechanism by which the positive electrode side reaction inhibitor inhibits the chlorine evolution side reaction in this invention mainly involves two aspects: Firstly, the positive electrode side reaction inhibitor forms a physical barrier on the surface of the positive electrode, hindering the Cl-... - Diffusion to the electrode surface reduces the Cl concentration on the electrode surface. - The concentration of the inhibitor suppresses the chlorine evolution kinetics. On the other hand, the positive electrode side reaction inhibitor exhibits a competitive redox reaction with the chlorine evolution side reaction on the positive electrode surface. When the positive electrode reaches the potential for the chlorine evolution side reaction, the positive electrode side reaction inhibitor preferentially undergoes oxidation, rather than Cl. - The oxidation to Cl2 reaction inhibits the chlorine evolution process. In the positive electrode of this invention, the loading of the positive electrode side reaction inhibitor can be 6.60 × 10⁻⁶. -3 ~3.30×10 -2 mg / cm 3 For example, 6.60×10 -3 7×10 -3 8×10 -3 1×10 -2 1.5×10 -2 2×10 -2 2.5×10 -2 3×10 -2 .

[0055] In this invention, the surface of the negative electrode includes metal nanoparticles that act as inhibitors of negative electrode side reactions. The metal in the metal nanoparticles can be one or more selected from tin, bismuth, and antimony. The mechanism by which the negative electrode side reaction inhibitor inhibits the hydrogen evolution side reaction in this invention mainly involves two aspects: Firstly, the negative electrode side reaction inhibitor has a high hydrogen evolution overpotential. When the negative electrode side reaction inhibitor is distributed on the electrode surface, it preferentially occupies sites with high hydrogen evolution activity, thereby inhibiting H2O. + The adsorption and reduction of H2 reduces its generation. On the other hand, when the negative electrode side reaction inhibitor is deposited on the carbon-based electrode surface, electrons tend to transfer from the negative electrode side reaction inhibitor to the carbon-based electrode surface, making the surface of the negative electrode side reaction inhibitor positively charged and repelling H2. + This reduces H + The adsorption and reduction of the inhibitor suppress the generation of hydrogen evolution side reactions. In the negative electrode of this invention, the loading of the negative electrode side reaction inhibitor can be 4.78 × 10⁻⁶. -3 ~1.80×10 -2 mg / cm 3 For example, 5×10 -3 7×10 -3 9×10 -3 1×10 -2 1.5×10 -2 1.8×10 -2 .

[0056] The present invention provides a method for preparing the vanadium redox flow battery of the present invention, comprising: charging the vanadium redox flow battery precursor of the present invention with constant current to obtain the vanadium redox flow battery; during the constant current charging process, the positive electrode electrolyte precursor is converted into a positive electrode electrolyte, and the negative electrode electrolyte precursor is converted into a negative electrode electrolyte.

[0057] In the constant current charging of this invention, the charging voltage is 1~1.55V. In the constant current charging of this invention, the current density is 5~20mA / cm². 2 In this invention, controlling the current density within the aforementioned range facilitates the deposition of positive / negative electrode side reaction inhibitor precursors onto the electrodes, thereby reducing side reactions and improving the performance of the vanadium redox flow battery.

[0058] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the invention. The methods, reagents, and materials used in the embodiments are conventional methods, reagents, and materials in the art, unless otherwise stated. The raw material compounds in the embodiments are all commercially available.

[0059] Example 1

[0060] The preparation of the all-vanadium redox flow battery in this embodiment specifically includes the following steps:

[0061] (S1) A positive electrode side reaction inhibitor precursor solution with a concentration of 1.0 mol / L aniline and 1.0 mol / L hydrochloric acid was prepared by mixing aniline, hydrochloric acid and water; a negative electrode side reaction inhibitor precursor solution with a concentration of 0.5 mol / L stannous chloride and 1.0 mol / L hydrochloric acid was prepared by mixing stannous chloride, hydrochloric acid and water.

[0062] (S2) Add the positive electrode side reaction inhibitor precursor solution and the negative electrode side reaction inhibitor precursor solution to the positive electrode electrolyte storage tank and the negative electrode electrolyte storage tank containing sulfuric acid-hydrochloric acid mixed acid electrolyte, respectively. Circulate the electrolyte by pumping or by stirring, shaking, etc., to ensure that aniline and stannous chloride are evenly distributed in the electrolyte, thus obtaining the positive electrode electrolyte precursor and the negative electrode electrolyte precursor. In the sulfuric acid-hydrochloric acid mixed acid electrolyte, the solvent is water, the concentration of vanadium ions is 1.70 mol / L, the valence state of vanadium ions is +3.5, the concentration of hydrochloric acid is 4.6 mol / L, and the concentration of sulfuric acid is... The concentration of aniline in the positive electrode electrolyte precursor is 0.1 mol / L, the valence state of vanadium ions is +3.5, the concentration of vanadium ions is 1.70 mol / L, the concentration of hydrochloric acid is 4.6 mol / L, and the concentration of sulfuric acid is 2.1 mol / L. The concentration of tin ions in the negative electrode electrolyte precursor is 0.05 mol / L, the valence state of vanadium ions is +3.5, the concentration of vanadium ions is 1.70 mol / L, the concentration of hydrochloric acid is 4.6 mol / L, and the concentration of sulfuric acid is 2.1 mol / L.

[0063] (S3) A vanadium redox flow battery precursor is assembled using carbon felt electrodes (as the substrate for both the positive and negative electrodes), a perfluorosulfonic acid ion exchange membrane, graphite bipolar plate components, the positive electrolyte precursor prepared in step (2), and the negative electrolyte precursor prepared in step (2). Appropriate components are selected to control the battery compression ratio to approximately 25%. The area S of the carbon felt electrode is 40 cm². 3 The volume V of the positive electrolyte precursor and the negative electrolyte precursor prepared in step (2) is 100 mL.

[0064] (S4) The vanadium redox flow battery precursor is charged with a constant current, wherein the charging voltage is 1-1.55V and the charging current density is 10mA / cm². 2 Under the influence of a constant current, aniline polymerizes on the surface of the positive electrode substrate to form polyaniline, a positive electrode side reaction inhibitor. 2+ Sn nanoparticles, which inhibit negative electrode side reactions, are generated on the surface of the negative electrode substrate through a reduction reaction. At this time, a positive electrode electrolyte, a positive electrode, a negative electrode electrolyte, and a negative electrode are obtained, and an all-vanadium redox flow battery is obtained.

[0065] Example 2

[0066] This embodiment is identical to Embodiment 1 in all other conditions, except that the initial charging current density in this embodiment is 5 mA / cm². 2 .

[0067] Example 3

[0068] This embodiment is identical to Embodiment 1 in all other conditions, except that the initial charging current density in this embodiment is 20 mA / cm². 2 .

[0069] Example 4

[0070] This embodiment is the same as Embodiment 1 in all other conditions, except that the concentration of aniline in the positive electrolyte precursor is 0.05 mol / L and the concentration of tin ions in the negative electrolyte precursor is 0.02 mol / L.

[0071] Example 5

[0072] This embodiment is the same as Embodiment 1 in all other conditions, except that the concentration of aniline in the positive electrolyte precursor is 0.2 mol / L and the concentration of tin ions in the negative electrolyte precursor is 0.08 mol / L.

[0073] Comparative Example 1

[0074] This comparative example is the same as Example 1 under the same conditions, except that no negative electrode side reaction inhibitor precursor solution is added to this comparative example.

[0075] Comparative Example 2

[0076] This comparative example is the same as Example 1 in all other conditions, except that no positive electrode side reaction inhibitor precursor solution is added to this comparative example.

[0077] Comparative Example 3

[0078] This comparative example is the same as Example 1 under the same conditions, except that no negative electrode side reaction inhibitor precursor solution or positive electrode side reaction inhibitor precursor solution is added to this comparative example.

[0079] Test Example 1

[0080] Take 5 mL of each of Examples 1-5, including the positive electrode electrolyte precursor and the negative electrode electrolyte precursor, to test the concentrations of aniline and tin. The concentration of aniline in the positive electrode electrolyte precursor was measured using high-performance liquid chromatography (HPLC), and the concentration of tin in the negative electrode electrolyte precursor was measured using inductively coupled plasma spectroscopy (ICP). The measured concentrations of aniline in the positive electrode electrolyte precursor and tin in the negative electrode electrolyte precursor are denoted as C. p0 and C n0After the vanadium redox flow battery precursors in Examples 1-5 were fully charged using constant current, 5 mL of each electrolyte (positive and negative) was taken from the positive and negative electrodes in Examples 1-5 to test the concentrations of remaining aniline and tin. The measured concentrations of aniline in the positive electrode electrolyte and tin in the negative electrode electrolyte were recorded as C. p1 and C n1 Among them, the loading amount of polyaniline on the positive electrode L p Through formula L p = (C p1 -C p0 )V / S calculation, the tin loading L on the negative electrode n Through formula L n = (C n1 -C n0 V / S calculation. Based on the above formula, the polyaniline loading of the positive electrode and the tin loading of the negative electrode in the all-vanadium redox flow batteries prepared in Examples 1-5 are shown in Table 1.

[0081] Table 1: Polyaniline loading of the positive electrode and tin loading of the negative electrode in the vanadium redox flow batteries prepared in Examples 1-5

[0082]

[0083] Test Example 2

[0084] Using a constant current testing method, with a charging upper limit voltage of 1.55V and a discharging lower limit voltage of 1.0V, the current densities were 80, 110, 150, 200, and 250 mA / cm², respectively. 2 The energy efficiency of the vanadium redox flow batteries prepared in Examples 1-5 and Comparative Examples 1-3 was tested under the following conditions. The batteries were cycled 5 times at each current density, and the data from the 4th cycle was plotted in Table 2.

[0085] Table 2: Energy efficiency of all-vanadium redox flow batteries prepared in Examples 1-5 and Comparative Examples 1-3

[0086]

[0087] As shown in Table 2, when the current density is 200 mA / cm² 2 At that time, the energy efficiency of Comparative Example 3, which did not add side reaction inhibitors to either the positive or negative electrode, was 80.0%. Comparative Examples 1 and 2 showed slight improvements in energy efficiency due to the addition of side reaction inhibitors to one side of the positive and negative electrodes. Example 1 showed the greatest improvement in battery performance, at 200 mA / cm². 2 At the specified current density, the energy efficiency of Example 1 reached 83.2%, which is 3.2% higher than that of Comparative Example 3.

[0088] Test Example 3

[0089] (S1) After the test in Test Example 2, the vanadium redox flow batteries corresponding to Examples 1-5 and Comparative Examples 1-3 were disassembled, and the positive and negative electrodes were removed respectively. A piece with an area of ​​1×1cm was cut from each electrode. 2 The electrodes were used to test the electrochemical chlorine and hydrogen evolution performance.

[0090] (S2) A three-electrode system was used, with a graphite rod electrode as the counter electrode, a saturated calomel electrode as the reference electrode, and the electrode cut in S1 as the working electrode. The system was connected to an electrochemical workstation for LSV testing.

[0091] (S3) The current density on the LSV curve is read as 10 mA / cm². 2 The corresponding potential values ​​are used to reflect the side reaction performance of the examples and comparative examples. The test results are shown in Table 3.

[0092] Table 3: Gas evolution side reaction potentials in the examples and comparative examples

[0093]

[0094] As shown in Table 3, the chlorine evolution potential on the positive electrode side of Comparative Example 3 was 1.15 V vs. SCE, and the hydrogen evolution potential on the negative electrode side was -0.75 V vs. SCE. After adding side reaction inhibitors to the positive and negative electrodes respectively, the chlorine evolution potential of Example 1 increased to 1.39 V vs. SCE, and the hydrogen evolution potential decreased to -0.98 V vs. SCE, indicating that the side reaction inhibitors have an inhibitory effect on chlorine evolution at the positive electrode and hydrogen evolution at the negative electrode, thereby helping to improve battery performance.

Claims

1. A method of preparing an all-vanadium redox flow battery, characterized by, The method comprises constant current charging of a vanadium redox flow battery precursor to obtain a vanadium redox flow battery; the vanadium redox flow battery precursor comprises a positive electrolyte precursor and a negative electrolyte precursor; during the constant current charging, the positive electrolyte precursor is converted into a positive electrolyte, and the negative electrolyte precursor is converted into a negative electrolyte; The positive electrolyte precursor comprises vanadium ions, an inorganic acid, a positive side reaction inhibitor precursor, and a solvent; the positive side reaction inhibitor precursor is aniline; and the inorganic acid comprises hydrochloric acid. The negative electrolyte precursor comprises vanadium ions, an inorganic acid, a negative side reaction inhibitor precursor, and a solvent; the negative side reaction inhibitor precursor is a metal compound; the metal compound is selected from one or more of tin compounds, bismuth compounds, and antimony compounds; and the inorganic acid comprises hydrochloric acid.

2. The method of claim 1, wherein, The method has one or more of the following characteristics: In the positive electrolyte precursor, the concentration of the positive side reaction inhibitor precursor is 0.05-0.2 mol / L; In the positive electrolyte precursor, the concentration of the inorganic acid is 6.5-7.5 mol / L; In the positive electrolyte precursor, the concentration of the hydrochloric acid is 4.5-5.0 mol / L; In the positive electrolyte precursor, the inorganic acid further comprises sulfuric acid; In the positive electrolyte precursor, the solvent is water.

3. The method of claim 1, wherein, The method has one or more of the following characteristics: In the negative electrolyte precursor, the concentration of the negative side reaction inhibitor precursor is 0.02-0.08 mol / L; In the negative electrolyte precursor, the concentration of the inorganic acid is 6.5-7.5 mol / L; In the negative electrolyte precursor, the concentration of the hydrochloric acid is 4.5-5.0 mol / L; In the negative electrolyte precursor, the inorganic acid further comprises sulfuric acid; In the negative electrolyte precursor, the solvent is water; The metal compound is selected from one or more of metal chlorides.

4. The method of claim 1, wherein, The vanadium redox flow battery precursor further comprises a positive electrode substrate, a negative electrode substrate, and a separator.

5. The method of claim 4, wherein The positive electrode substrate is a carbon-based electrode; the carbon-based electrode is carbon felt, carbon cloth, or carbon paper; and / or The negative electrode substrate is a carbon-based electrode; the carbon-based electrode is carbon felt, carbon cloth, or carbon paper.

6. The method of claim 1, wherein, In the constant current charging, the charging voltage is 1-1.55 V.

7. The method of claim 1, wherein, In the constant current charging, the current density is 5-20 mA / cm 2 .

8. An all-vanadium redox flow battery prepared by the method of any one of claims 1-7, characterized in that, The vanadium redox flow battery comprises a positive electrode, a negative electrode, a positive electrolyte, and a negative electrolyte; the surface of the positive electrode comprises polyaniline as a positive side reaction inhibitor; the surface of the negative electrode comprises metal nanoparticles as a negative side reaction inhibitor; and the metal in the metal nanoparticles is selected from one or more of tin, bismuth, and antimony.

9. The vanadium redox flow battery of claim 8, wherein The loading amount of the positive electrode side reaction inhibitor in the positive electrode is 6.60 x 10 -3 -3.30 x 10 -2 mg / cm 3 ; and / or The loading amount of the negative electrode side reaction inhibitor in the negative electrode is 4.78 x 10 -3 1.80 x 10 -2 mg / cm 3 .

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