Method for preparing vanadyl sulfate by using spent vanadium battery electrolyte

Abstract

The invention relates to a method for preparing vanadyl sulfate by using a failure vanadium cell electrolyte. The method comprises the following steps of (A) taking the failure vanadium cell electrolyte as a raw material, testing total vanadium concentration and average valence state of the failure electrolyte by a method of potentiometric titration or cheicaml titration for estimating electrolysis time, and simultaneously testing sulfate radical concentration of the failure electrolyte by a method of chemical deposition; (B) adjusting the vanadium concentration of the failure concentration to be 1-4moL / L, preferably 1.5-3.5moL / L and the sulfate radical concentration to be 2-8moL / L, preferably 3-7moL / L by adding vanadium pentoxide or sulfuric acid and water; (C) carrying out electrolysis on the electrolyte to tetravalence by using an electrolysis groove according to the electrolysis time estimated in the step (A), monitoring the electrolyte, and carrying out electrolysis to trivalent or pentavalent vanadium to obtain a vanadyl sulfate solution; and (D) carrying out evaporation or solvent-out crystallization on the vanadyl sulfate solution to obtain the vanadyl sulfate.

Description

technical field [0001] The invention relates to the field of all-vanadium redox flow batteries, and more specifically relates to the preparation of vanadyl sulfate by utilizing the electrolyte solution of spent vanadium batteries. Background technique [0002] The all-vanadium electrolyte is an important part of the vanadium battery and a carrier for energy storage. In recent years, with the rise of vanadium batteries, the production of all-vanadium electrolytes is increasing. However, as the battery system continues to charge and discharge, the positive and negative electrodes of the all-vanadium electrolyte will not match, resulting in an energy imbalance that cannot be used normally. The treatment of spent electrolyte is an urgent problem faced by many vanadium battery manufacturers. This patent mainly solves the problem of disposing of the invalid electrolyte of the vanadium battery. [0003] The all-vanadium redox flow battery has the advantages of high energy conver...

AI Technical Summary

Problems solved by technology

Although this method can make the vanadium recovery rate more than 80%, there are still some disadvantages

First of all, pentavalent vanadium ions are very easy to precipitate when the temperature is higher than 40°C, and the high-concentration spent electrolyte is likely to be precipitated during the electrolysis process; secondly, the use of organic solvents to reduce pentavalent vanadium ions requires a higher temperature (generally at 100°C or so), the equipment requirements are high, and the amount of reducing agent is difficult to control, it is easy to reduce completely or introduce organic impurities; finally, the whole preparation process is complicated and time-consuming, which is not conducive to large-scale mass production

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