Preparation method of electrolyte for vanadium redox battery (VRB)

Abstract

The invention relates to a preparation method of an electrolyte for a vanadium redox battery (VRB), wherein the electrolyte for the VRB is prepared by means of an electrolytic process, the electrolyte for the VRB prepared by means of an electrolytic process is a quadrivalent vanadium ion solution, and the preparation method comprises the following basic steps: 1) preparing a mixed solution composed of sulfuric acid and vanadium sulphate, adding vanadium pentoxide powder into a 98% sulfuric acid solution, then heating and stirring, and then diluting with distilled water to prepare a mixed solution comprising sulfuric acid and vanadium sulphate; 2) filtering the mixed solution comprising sulfuric acid and vanadium sulphate to remove a small quantity of insoluble vanadium pentoxide to obtain a mixed solution comprising sulfuric acid and vanadium sulphate, wherein the mixed solution can meet the requirements for the preparation of the quadrivalent vanadium ion solution; and 3) pouring the mixed solution comprising sulfuric acid and vanadium sulphate into an electrolytic cell without a diaphragm to electrolyze to obtain a quadrivalent vanadium ion solution. The preparation method provided by the invention has the advantages that the preparation cost is reduced and the process is simple.

Description

technical field [0001] The invention belongs to the field of energy storage batteries, and in particular relates to a method for preparing an electrolyte for an all-vanadium redox flow battery. Background technique [0002] As far as the applicant knows, the current methods for preparing the electrolyte solution for all-vanadium redox flow batteries mainly include chemical methods and electrolytic methods. The chemical method is to use the oxide or compound of vanadium to produce the electrolyte solution for vanadium battery by heating or adding a certain amount of reducing agent in a certain sulfuric acid solution. The chemical method to prepare the electrolyte solution for vanadium batteries is simple and does not require high equipment, but the disadvantage is that because the vanadium pentoxide and vanadium trioxide required for the preparation of the electrolyte are solid powders, the dissolution rate is slow and the production capacity is low. The addition of reducing...

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Problems solved by technology

[0004] According to the results of research and tests, the applicant believes that the method for electrolytic preparation of vanadium electrolyte proposed in the above-mentioned disclosed patents and articles has the following disadvantages: 1. The solubility of vanadium pentoxide powder in sulfuric acid solution is not large, and the electrolytic reaction speed is relatively slow , needs to be added in batches, which leads to complicated steps; 2. Since the vanadium pentoxide powder is reduced on the surface of the negative electrode, it is necessary to suspend the vanadium pentoxide powder in the solution and contact the negative electrode by means of stirring or nitrogen gas for reduction , which will lead to a small amount of preparation and a long electrolysis time; 3. When the positive electrode electrolyte is a sulfuric acid solution or a mixed solution of sodium sulfate and sulfuric acid, the osmotic pressure on both sides of the diaphragm is different, there will be water migration, or a large amount of electrolysis will occur. The sodium ions enter the negative chamber from the positive chamber through the diaphragm, which reduces the amount of free water molecules in the negative electrolyte, and at the same time causes the association of vanadyl hydration ions to form macromolecular groups, increasing the conductivity of the electrolyte. reduce

4. The vanadium solution obtained by direct electrolysis of ammonium vanadate in sulfuric acid solution introduces impurities such as calcium ions in the process of adjusting the pH value, which is not easy to purify and has an impact on battery performance. When ammonium ions are removed, ammonia gas will be released, which is harmful to the environment. unfriendly

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