All-vanadium redox flow battery precursor, all-vanadium redox flow battery and preparation method of all-vanadium redox flow battery

Abstract

The invention belongs to the field of all-vanadium redox flow batteries, and particularly relates to an all-vanadium redox flow battery precursor, an all-vanadium redox flow battery and a preparation method of the all-vanadium redox flow battery. The all-vanadium redox flow battery precursor comprises a positive electrode electrolyte precursor and a negative electrode electrolyte precursor, the positive electrolyte precursor comprises vanadium ions, inorganic acid, a positive side reaction inhibitor precursor and a solvent; wherein the positive side reaction inhibitor precursor is aniline; the inorganic acid contains hydrochloric acid; the negative electrode electrolyte precursor comprises vanadium ions, 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 a tin compound, a bismuth compound and an antimony compound; the inorganic acid comprises hydrochloric acid.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of all-vanadium redox flow battery, and in particular, relates to an all-vanadium redox flow battery precursor, an all-vanadium redox flow battery and a preparation method thereof. BACKGROUND

[0002] All-vanadium redox flow battery is a large-scale energy storage technology based on the redox reaction of vanadium ions, which realizes energy storage and release by reversible conversion of vanadium ions in different valence states in electrolyte. Vanadium battery has the advantages of super-long cycle life, high safety, independent adjustable capacity and power, environmental protection and no pollution, etc. With the progress of technology and large-scale application, all-vanadium redox flow battery is expected to become a key solution in the field of long-time energy storage.

[0003] The electrolyte of all-vanadium redox flow battery is the core of energy storage, which is composed of vanadium ions in different valence states dissolved in an acidic solution (such as sulfuric acid or sulfuric acid-hydrochloric acid mixed acid). Sulfuric acid-hydrochloric acid mixed acid electrolyte (H2SO4 + HCl) is a high-performance electrolyte system in all-vanadium redox flow battery. Compared with sulfuric acid-based electrolyte, the sulfuric acid-hydrochloric acid mixed acid electrolyte combines the advantages of sulfuric acid and hydrochloric acid, which can significantly improve the solubility of vanadium ions and the stability of electrolyte, and has become one of the important paths to break through the performance bottleneck of all-vanadium redox flow battery.

[0004] However, when all-vanadium redox flow battery uses sulfuric acid-hydrochloric acid mixed acid electrolyte, the gas evolution side reaction of the positive and negative electrodes is a key challenge. During the charging process, with the change of potential, Cl - on the positive side of the vanadium battery will be oxidized to Cl2, and H + on the negative side will be reduced to H2. The positive and negative side reactions will cause the imbalance of vanadium ion valence, resulting in loss of battery capacity. The Cl2 generated on the positive side will corrode the electrode material, causing damage to the key materials such as ion membrane, thereby affecting the service life of the vanadium battery. In addition, the mixture of Cl2 and H2 produced by the side reaction may form an explosive environment.

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

[0006] To solve the problems existing in the prior art, the present application provides a positive electrolyte precursor containing a positive side reaction inhibitor precursor and a negative electrolyte precursor containing a negative side reaction inhibitor precursor, forming a side reaction inhibitor combination. With the first charging process of the all-vanadium redox flow battery precursor, the two side reaction inhibitor precursors generate side reaction inhibitors. The present application simultaneously inhibits the chlorine evolution and hydrogen evolution side reactions of the hydrochloric acid-based all-vanadium redox flow battery through the synergistic effect of the side reaction inhibitor combination, which helps to improve the performance of the all-vanadium redox flow battery and ensure the safety of the hydrochloric acid-based all-vanadium redox flow battery.

[0007] Specifically, the present application provides a vanadium redox flow battery precursor, the vanadium redox flow battery precursor comprising a positive electrolyte precursor and a negative electrolyte precursor; the positive electrolyte precursor comprising vanadium ions, an inorganic acid, a positive side reaction inhibitor precursor and a solvent; wherein the positive side reaction inhibitor precursor is aniline; the inorganic acid comprises hydrochloric acid; the negative electrolyte precursor comprising vanadium ions, an inorganic acid, a negative side reaction inhibitor precursor and a solvent; wherein 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; the inorganic acid comprises hydrochloric acid.

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

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

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

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

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

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

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

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

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

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

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

[0019] In one or more embodiments, the all-vanadium redox flow battery precursor further comprises 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 application provides an all-vanadium redox flow battery, which 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, the metal in the metal nanoparticles is selected from one or more of tin, bismuth and antimony.

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

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

[0025] The present application provides a method for preparing the all-vanadium redox flow battery described in the present application, which comprises constant current charging the all-vanadium redox flow battery precursor of the present application to obtain the all-vanadium redox flow battery; during the constant current charging, the positive electrolyte precursor is converted into the positive electrolyte and the negative electrolyte precursor is converted into the negative electrolyte.

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

[0027] In one or more embodiments, in the constant current charging, the current density is 5-20mA / cm 2 .

[0028] Compared with the prior art, the present application has the following beneficial technical effects: (1) The adding method of the side reaction inhibitor precursor of the application is simple, and with the first charging process of the vanadium redox flow battery precursor, the positive side forms a positive side reaction inhibitor on the surface of the positive electrode fiber by polymerization reaction in the charging process to inhibit the chlorine evolution side reaction, and the negative side also forms a negative side reaction inhibitor on the surface of the negative electrode fiber by reduction reaction in the charging process to inhibit the hydrogen evolution reaction, both of which are formed following the charging process of the battery, and the preparation process is simple; (2) The side reaction inhibitor prepared by the electrodeposition method has good stability and does not affect the service life of the electrode; (3) The side reaction inhibitor combination of the application can simultaneously inhibit the chlorine evolution and hydrogen evolution side reactions of the hydrochloric acid-based vanadium redox flow battery, 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 DESCRIPTION

[0029] In order for those skilled in the art to understand the characteristics and effects of the present application, the following will generally describe and define the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used in the text are of the usual meaning understood by those skilled in the art of the present application, and in case of conflict, the definition in the specification shall prevail.

[0030] Theories or mechanisms described and disclosed herein, whether correct or not, should not be used to limit the scope of the present application, i.e., the present application can be practiced without being limited by any particular theory or mechanism.

[0031] In this text, "contains", "includes", "contains" and similar phrases cover the meaning of "essentially composed of" and "composed of", for example, when the text discloses "A contains B and C", "A essentially consists of B and C" and "A consists of B and C" should be considered to have been disclosed herein.

[0032] In this text, all features defined in the form of numerical range or percentage range, such as numerical value, quantity, content and concentration, are only for the sake of brevity and convenience. Therefore, the description of numerical range or percentage range should be considered to have covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0033] In this text, unless otherwise specified, percentage refers to mass percentage, and ratio refers to mass ratio.

[0034] In this text, when describing the embodiments or examples, it should be understood that they are not intended to limit the application to these embodiments or examples. On the contrary, all alternatives, modifications and equivalents of the methods and materials described in the application can be covered within the scope defined by the claims.

[0035] Herein, all possible combinations of the technical features in each embodiment or example are not described in order to make the description simple. Therefore, as long as the combinations of the technical features do not contradict each other, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope of the present specification.

[0036] The all-vanadium redox flow battery precursor provided by the application comprises a positive electrolyte precursor and a negative electrolyte precursor; the positive electrolyte precursor comprises vanadium ions, an inorganic acid, a positive side reaction inhibitor precursor, and a solvent; the inorganic acid in the positive electrolyte precursor comprises hydrochloric acid; the negative electrolyte precursor comprises vanadium ions, an inorganic acid, a negative side reaction inhibitor precursor, and a solvent; and the inorganic acid in the negative electrolyte precursor comprises hydrochloric acid.

[0037] In the application, the positive side reaction inhibitor precursor is aniline (C6H7N). In the application, the aniline is continuously oxidized to generate a free radical cation on the surface of the positive electrode under the action of a constant current, and gradually polymerizes into a positive side reaction inhibitor polyaniline through a coupling reaction.

[0038] In the application, the negative side reaction inhibitor precursor is a metal compound; the metal compound can be one or more selected from tin compounds, bismuth compounds, and antimony compounds. In the application, the metal compound can be one or more selected from metal chlorides. The metal chlorides have good solubility in water, do not introduce new anions, and avoid affecting the performance of the electrolyte. In the application, the metal ions of the metal compound gain electrons on the surface of the negative electrode under the action of a constant current, and gradually reduce to metal nanoparticles through a reduction reaction.

[0039] In the positive electrolyte precursor of the application, the concentration of the positive 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, or 0.2 mol / L. In the application, too much addition of the positive side reaction inhibitor precursor will affect the performance, and the content of the positive side reaction inhibitor precursor is controlled in the above range, which is beneficial to reducing the side reaction of the positive electrode and improving the energy efficiency of the all-vanadium redox flow battery. In the negative electrolyte precursor of the application, the concentration of the negative 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, or 0.07 mol / L. In the application, too much addition of the negative side reaction inhibitor precursor will affect the performance, and the content of the negative side reaction inhibitor precursor is controlled in the above range, which is beneficial to reducing the side reaction of the negative electrode and improving the energy efficiency of the all-vanadium redox flow battery.

[0040] The valence of the vanadium ion in the positive electrolyte precursor of the present application can be +3.5. The concentration of the vanadium ion in the positive electrolyte precursor of the present application can be 1.60-1.75 mol / L, such as 1.60 mol / L, 1.62 mol / L, 1.64 mol / L, 1.68 mol / L, 1.70 mol / L, 1.72 mol / L, 1.75 mol / L. The concentration of the inorganic acid in the positive electrolyte precursor of the present application can be 6.5-7.5 mol / L, such as 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, 7.5 mol / L. The concentration of the hydrochloric acid in the positive electrolyte precursor of the present application can be 4.5-5.0 mol / L, such as 4.5 mol / L, 4.6 mol / L, 4.7 mol / L, 4.8 mol / L, 4.9 mol / L, 5.0 mol / L. The inorganic acid in the positive electrolyte precursor of the present application can also comprise sulfuric acid. The solvent in the positive electrolyte precursor of the present application can be water.

[0041] The valence of the vanadium ion in the negative electrolyte precursor of the present application can be +3.5. The concentration of the vanadium ion in the negative electrolyte precursor of the present application can be 1.60-1.75 mol / L, such as 1.60 mol / L, 1.62 mol / L, 1.64 mol / L, 1.68 mol / L, 1.70 mol / L, 1.72 mol / L, 1.75 mol / L. The concentration of the inorganic acid in the negative electrolyte precursor of the present application can be 6.5-7.5 mol / L, such as 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, 7.5 mol / L. The concentration of the hydrochloric acid in the negative electrolyte precursor of the present application can be 4.5-5.0 mol / L, such as 4.5 mol / L, 4.6 mol / L, 4.7 mol / L, 4.8 mol / L, 4.9 mol / L, 5.0 mol / L. The inorganic acid in the negative electrolyte precursor of the present application can also comprise sulfuric acid. The solvent in the negative electrolyte precursor of the present application can be water.

[0042] The present application provides a method for preparing the positive electrolyte precursor of the present application, which can comprise directly adding the positive side reaction inhibitor precursor to the positive electrolyte base to obtain the positive electrolyte precursor. The present application provides a method for preparing the negative electrolyte precursor of the present application, which can comprise directly adding the negative side reaction inhibitor precursor to the negative electrolyte base to obtain the negative electrolyte precursor.

[0043] The present application provides a method for preparing the positive electrolyte precursor of the present application, which can comprise adding the positive side reaction inhibitor precursor solution directly into the positive electrolyte base to obtain the positive electrolyte precursor. The present application provides a method for preparing the negative electrolyte precursor of the present application, which can comprise adding the negative side reaction inhibitor precursor solution directly into the negative electrolyte base to obtain the negative electrolyte precursor.

[0044] In the present application, the positive side reaction inhibitor precursor solution comprises a positive side reaction inhibitor precursor, an inorganic acid and a solvent, wherein the inorganic acid comprises hydrochloric acid. In the positive side reaction inhibitor precursor solution of the present application, the concentration of the positive side reaction inhibitor precursor 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, 1.5 mol / L. In the positive side reaction inhibitor precursor solution of the present application, the solvent can be water. In the positive side reaction inhibitor precursor solution of the present application, the concentration of the inorganic 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, 1.0 mol / L. In the positive side reaction inhibitor precursor solution of the present application, the concentration of the 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, 1.0 mol / L. In the positive side reaction inhibitor precursor solution of the present application, the inorganic acid can also comprise sulfuric acid.

[0045] In the present application, 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 the negative electrode side reaction inhibitor precursor solution of the present application, the concentration of the negative electrode side reaction inhibitor precursor 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, 1.5 mol / L. In the negative electrode side reaction inhibitor precursor solution of the present application, the solvent can be water. In the negative electrode side reaction inhibitor precursor solution of the present application, the concentration of the inorganic 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, 1.0 mol / L. In the negative electrode side reaction inhibitor precursor solution of the present application, the concentration of the 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, 1.0 mol / L. In the negative electrode side reaction inhibitor precursor solution of the present application, the inorganic acid can further comprise sulfuric acid.

[0046] In the present application, the positive electrode side reaction inhibitor precursor solution can be obtained by dissolving the positive electrode side reaction inhibitor precursor in an acidic solution; and the negative electrode side reaction inhibitor precursor solution can be obtained by dissolving the negative electrode side reaction inhibitor precursor in an acidic solution.

[0047] In the present application, the positive electrode electrolyte base comprises vanadium ions, an inorganic acid and a solvent, wherein the inorganic acid comprises hydrochloric acid. In the positive electrode electrolyte base of the present application, the solvent is water. In the positive electrode electrolyte base of the present application, the inorganic acid can further comprise sulfuric acid.

[0048] In the present application, the negative electrode electrolyte base comprises vanadium ions, an inorganic acid and a solvent, wherein the inorganic acid comprises hydrochloric acid. In the negative electrode electrolyte base of the present application, the solvent is water. In the negative electrode electrolyte base of the present application, the inorganic acid can further comprise sulfuric acid.

[0049] The all-vanadium redox flow battery precursor of the present application further comprises a positive electrode substrate, a negative electrode substrate and a separator. In the present application, the positive electrode substrate can be a carbon-based electrode; the carbon-based electrode can be carbon felt, carbon cloth or carbon paper. In the present application, the negative electrode substrate can be a carbon-based electrode; the carbon-based electrode can be carbon felt, carbon cloth or carbon paper.

[0050] The all-vanadium redox flow battery provided by the present application comprises a positive electrode, a negative electrode, a positive electrode electrolyte and a negative electrode electrolyte.

[0051] In the present application, the positive electrode surface comprises polyaniline as a positive electrode side reaction inhibitor. The mechanism of the positive electrode side reaction inhibitor inhibiting the chlorine evolution side reaction in the present application mainly has two aspects: on the one hand, the positive electrode side reaction inhibitor forms a physical barrier on the positive electrode surface, hinders the diffusion of Cl - to the electrode surface, reduces the Cl - concentration on the electrode surface, and thus inhibits the chlorine evolution kinetics; on the other hand, the positive electrode side reaction inhibitor has a competitive redox reaction with the chlorine evolution side reaction on the positive electrode surface. When the positive electrode reaches the potential of the chlorine evolution side reaction, the positive electrode side reaction inhibitor will preferentially oxidize, rather than the reaction of Cl - to Cl2, thereby inhibiting the chlorine evolution process. In the positive electrode of the present application, the loading of the positive electrode side reaction inhibitor can be 6.60×10 -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 .

[0052] In the present application, the negative electrode surface comprises metal nanoparticles as a negative electrode side reaction inhibitor, and the metal in the metal nanoparticles can be one or more selected from tin, bismuth and antimony. The mechanism of the negative electrode side reaction inhibitor inhibiting the hydrogen evolution side reaction in the present application mainly has two aspects: on the one hand, the negative electrode side reaction inhibitor has a high hydrogen evolution overpotential, and when the negative electrode side reaction inhibitor is distributed on the electrode surface, it will preferentially occupy the sites with high hydrogen evolution activity, thereby inhibiting the adsorption and reduction of H + , and reducing the generation of H2; on the other hand, when the negative electrode side reaction inhibitor is deposited on the carbon-based electrode surface, the 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 H + , thereby reducing the adsorption and reduction of H + , and inhibiting the generation of the hydrogen evolution side reaction. In the negative electrode of the present application, the loading of the negative electrode side reaction inhibitor can be 4.78×10 -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 .

[0053] The application provides a method for preparing the all-vanadium redox flow battery, which comprises: performing constant current charging on the all-vanadium redox flow battery precursor to obtain the all-vanadium redox flow battery; during the constant current charging, the positive electrolyte precursor is converted into the positive electrolyte, and the negative electrolyte precursor is converted into the negative electrolyte.

[0054] In the constant current charging, the charging voltage is 1-1.55 V, and the current density is 5-20 mA / cm 2 In the application, the current density is controlled within the range, which is beneficial to the deposition of the positive / negative side reaction inhibitor precursor on the electrode, thereby reducing the side reaction and improving the performance of the all-vanadium redox flow battery.

[0055] The application will be described below in the manner of specific examples. It should be understood that the examples are merely illustrative and are not intended to limit the scope of the application. The methods, reagents and materials used in the examples are conventional in the art unless otherwise specified. The raw material compounds in the examples can be purchased through commercial channels.

[0056] Example 1 The preparation of the all-vanadium redox flow battery in this example specifically comprises the following steps: (S1) mixing aniline, hydrochloric acid and water to prepare a positive side reaction inhibitor precursor solution with an aniline concentration of 1.0 mol / L and a hydrochloric acid concentration of 1.0 mol / L; mixing stannous chloride, hydrochloric acid and water to prepare a negative side reaction inhibitor precursor solution with a stannous chloride concentration of 0.5 mol / L and a hydrochloric acid concentration of 1.0 mol / L.

[0057] (S2) adding the positive side reaction inhibitor precursor solution and the negative side reaction inhibitor precursor solution into the positive electrolyte tank and the negative electrolyte tank with sulfuric acid-hydrochloric acid mixed acid electrolyte respectively, and circulating the electrolyte by pumping or uniformly distributing the aniline and stannous chloride in the electrolyte by stirring, oscillation or the like to obtain the positive electrolyte precursor and the negative 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 of vanadium ions is +3.5, the concentration of hydrochloric acid is 4.6 mol / L, and the concentration of sulfuric acid is 2.1 mol / L; in the positive electrolyte precursor, the concentration of aniline is 0.1 mol / L, the valence 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; in the negative electrolyte precursor, the concentration of stannous ions is 0.05 mol / L, the valence 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.

[0058] (S3) Select carbon felt electrode (as positive electrode substrate and negative electrode substrate), perfluorosulfonic acid ion membrane, graphite bipolar plate fittings, the positive electrolyte precursor prepared in step (2) and the negative electrolyte precursor prepared in step (2) to assemble a vanadium redox flow battery precursor, and select the appropriate fittings to control the battery compression ratio at about 25%; wherein the area S of the carbon felt electrode is 40 cm 3 , the volume V of the positive electrolyte precursor prepared in step (2) and the negative electrolyte precursor prepared in step (2) is 100 mL.

[0059] (S4) Constant current charging of the vanadium redox flow battery precursor, wherein the charging voltage is 1-1.55V, and the charging current density is 10mA / cm 2 Under the action of constant current, aniline is polymerized on the surface of the positive electrode substrate to form a positive side reaction inhibitor polyaniline, and Sn 2+ is generated on the surface of the negative electrode substrate by a reduction reaction to form a negative side reaction inhibitor Sn nanoparticle. At this time, the positive electrolyte, the positive electrode, the negative electrolyte and the negative electrode are obtained, and the vanadium redox flow battery is obtained.

[0060] Example 2 The conditions of this example and other conditions of example 1 are the same, and the only difference is that the current density of the initial charging of this example is 5mA / cm 2 .

[0061] Example 3 The conditions of this example and other conditions of example 1 are the same, and the only difference is that the current density of the initial charging of this example is 20mA / cm 2 .

[0062] Example 4 The conditions of this example and other conditions of example 1 are the same, and the only difference is that the concentration of aniline in the positive electrolyte precursor of this example is 0.05mol / L, and the concentration of tin ions in the negative electrolyte precursor is 0.02mol / L.

[0063] Example 5 The conditions of this example and other conditions of example 1 are the same, and the only difference is that the concentration of aniline in the positive electrolyte precursor of this example is 0.2mol / L, and the concentration of tin ions in the negative electrolyte precursor is 0.08mol / L.

[0064] Comparative Example 1 The conditions of this example and other conditions of example 1 are the same, and the only difference is that this example does not add a negative side reaction inhibitor precursor solution.

[0065] Comparative Example 2 The comparative example and other conditions of example 1 are the same, the only difference is that the comparative example does not add the positive electrode side reaction inhibitor precursor solution.

[0066] Comparative example 3 The comparative example and other conditions of example 1 are the same, the only difference is that the comparative example does not add the negative electrode side reaction inhibitor precursor solution and the positive electrode side reaction inhibitor precursor solution.

[0067] Test example 1 The aniline concentration in the positive electrode electrolyte precursor and the tin concentration in the negative electrode electrolyte precursor of each of examples 1-5 5mL were tested; wherein the aniline concentration in the positive electrode electrolyte precursor was tested by high performance liquid chromatography (HPLC), and the tin concentration in the negative electrode electrolyte precursor was tested by inductively coupled plasma spectroscopy (ICP), and the test concentration of aniline in the positive electrode electrolyte precursor and the test concentration of tin in the negative electrode electrolyte precursor were respectively recorded as C p0 and C n0 . After the constant current charging of the all-vanadium redox flow battery precursor of examples 1-5 was completed, 5mL of positive and negative electrode electrolyte of examples 1-5 was taken to test the remaining aniline and tin concentration, and the test concentration of aniline in the positive electrode electrolyte and the test concentration of tin in the negative electrode electrolyte were respectively recorded as C p1 and C n1 . Wherein the loading amount of polyaniline on the positive electrode L p was calculated by the formula L p = (C p1 -C p0 ) V / S, and the loading amount of tin on the negative electrode L n was calculated by the formula L n = (C n1 -C n0 ) V / S. According to the above formula, the polyaniline loading amount of the positive electrode and the tin loading amount of the negative electrode in the all-vanadium redox flow battery prepared in examples 1-5 are shown in Table 1.

[0068] Table 1: The polyaniline loading amount of the positive electrode and the tin loading amount of the negative electrode in the all-vanadium redox flow battery prepared in examples 1-5

[0069] Test example 2 The energy efficiency of the all-vanadium redox flow batteries prepared in examples 1-5 and comparative examples 1-3 was tested under the conditions that the upper limit voltage of charging was 1.55V, the lower limit voltage of discharging was 1.0V, and the current density was 80, 110, 150, 200, 250mA / cm 2 in turn, and each current density was cycled 5 times, and the data of the 4th time was used to draw Table 2.

[0070] Table 2: Energy efficiency of all-vanadium redox flow batteries prepared by Examples 1-5 and Comparative Examples 1-3

[0071] As shown in Table 2, when the current density is 200 mA / cm 2 , the energy efficiency of Comparative Example 3 without adding the side reaction inhibitor to both the positive and negative electrodes is 80.0%. The energy efficiency of Comparative Examples 1 and 2 is slightly improved due to the addition of the side reaction inhibitor to one side of the positive and negative electrodes. The battery performance of Example 1 is improved the most, and the energy efficiency of Example 1 reaches 83.2% at a current density of 200 mA / cm 2 , which is increased by 3.2% compared with Comparative Example 3.

[0072] Test Example 3 (S1) After the end of the test of Test Example 2, the positive and negative electrodes of the all-vanadium redox flow batteries corresponding to Examples 1-5 and Comparative Examples 1-3 were taken out, and one piece of electrode with an area of 1×1 cm 2 was cut from each of the electrodes, respectively, for the test of the electrochemical chlorine evolution and hydrogen evolution performance.

[0073] (S2) A three-electrode system was used, the counter electrode was a graphite rod electrode, the reference electrode was a saturated calomel electrode, the working electrode was the electrode cut in S1, and an electrochemical workstation was connected for LSV test.

[0074] (S3) The potential value corresponding to the current density of 10 mA / cm 2 on the LSV curve was read, and the side reaction performance of the examples and comparative examples was reflected by the potential value, and the test results are shown in Table 3.

[0075] Table 3: Gas evolution side reaction potential of examples and comparative examples

[0076] As shown in Table 3, the chlorine evolution potential of Comparative Example 3 at the positive electrode side is 1.15 V vs. SCE, and the hydrogen evolution potential at the negative electrode side is -0.75 V vs. SCE. After adding the side reaction inhibitor to the positive and negative electrodes, respectively, the chlorine evolution potential of Example 1 is increased to 1.39 V vs. SCE, and the hydrogen evolution potential is reduced to -0.98 V vs. SCE, which indicates that the side reaction inhibitor has an inhibitory effect on the chlorine evolution at the positive electrode and the hydrogen evolution at the negative electrode, thereby helping to improve the battery performance.

Claims

1. A precursor for an all-vanadium redox flow battery, characterized in that, The vanadium redox flow battery precursor 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; and 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.

2. The all-vanadium redox flow battery precursor as described in claim 1, characterized in that, The positive electrode electrolyte precursor has one or more of the following characteristics: In the positive electrode electrolyte precursor, the concentration of the positive electrode side reaction inhibitor precursor is 0.05~0.2 mol / L; In the positive electrode electrolyte precursor, the concentration of the inorganic acid is 6.5~7.5 mol / L; In the positive electrode electrolyte precursor, the concentration of hydrochloric acid is 4.5~5.0 mol / L; The inorganic acid in the positive electrode electrolyte precursor also includes sulfuric acid; In the positive electrode electrolyte precursor, the solvent is water.

3. The all-vanadium redox flow battery precursor as described in claim 1, characterized in that, The negative electrode electrolyte precursor has one or more of the following characteristics: In the negative electrode electrolyte precursor, the concentration of the negative electrode side reaction inhibitor precursor is 0.02~0.08 mol / L; In the negative electrode electrolyte precursor, the concentration of the inorganic acid is 6.5~7.5 mol / L; In the negative electrode electrolyte precursor, the concentration of hydrochloric acid is 4.5~5.0 mol / L; The inorganic acid in the negative electrode electrolyte precursor also includes sulfuric acid; In the negative electrode electrolyte precursor, the solvent is water; The metal compound is selected from one or more metal chlorides.

4. The all-vanadium redox flow battery precursor as described in claim 1, characterized in that, The vanadium redox flow battery precursor also includes a positive electrode substrate, a negative electrode substrate, and a separator.

5. The all-vanadium redox flow battery precursor as described in claim 4, characterized in that, 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. A vanadium redox flow battery, characterized in that, The vanadium redox flow battery includes a positive electrode, a negative electrode, a positive electrolyte, and a negative electrolyte. The surface of the positive electrode includes polyaniline as an inhibitor of positive electrode side reactions, and the surface of the negative electrode includes metal nanoparticles as an inhibitor of negative electrode side reactions. The metal in the metal nanoparticles is selected from one or more of tin, bismuth, and antimony.

7. The all-vanadium redox flow battery as described in claim 6, characterized in that, In the positive electrode, the loading of the positive electrode side reaction inhibitor is 6.60 × 10⁻⁶. -3 ~3.30×10 -2 mg / cm 3 ; and / or In the negative electrode, the loading of the negative electrode side reaction inhibitor is 4.78 × 10⁻⁶. -3 ~1.80×10 -2 mg / cm 3 .

8. A method for preparing the all-vanadium redox flow battery according to claim 6 or 7, characterized in that, The method includes constant current charging of the vanadium redox flow battery precursor according to any one of claims 1-5 to obtain a 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.

9. The method as described in claim 8, characterized in that, In the constant current charging process, the charging voltage is 1~1.55V.

10. The method as described in claim 8, characterized in that, In the constant current charging process, the current density is 5~20 mA / cm². 2 .

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