CN-121983629-A - High-stability electrolyte for all-vanadium redox flow battery and preparation method thereof

Abstract

The application relates to the field of flow batteries, in particular to a high-stability electrolyte for an all-vanadium flow battery and a preparation method thereof. The high-stability electrolyte for the all-vanadium redox flow battery comprises an electrolyte stock solution and a stabilizer, wherein the stabilizer comprises a polar solvent and pyrrole, the polar solvent comprises at least one of acetone and N-methylpyrrolidone, the concentration of vanadium in the electrolyte stock solution is 2.0-4.5 mol/L, the concentration of sulfate radical is 2-4 mol/L, the concentration of chloride ion is 3.2-5.8 mol/L, and the valence state of vanadium in the electrolyte stock solution is 2, 3, 4, 5 or intermediate valence state. According to the application, the polar solvent and pyrrole are used as the stabilizer, so that the problems that electrolyte solidification and vanadium ion precipitation crystallization easily occur in a subzero temperature environment of the all-vanadium redox flow battery are effectively solved, and the normal operation temperature range of the all-vanadium redox flow battery is widened.

Inventors

• WU XIONGWEI
• XIE HAO
• WU XUEWEN
• LI ZHIGANG

Assignees

• 湖南省银峰新能源有限公司

Dates

Publication Date

20260505

Application Date

20260407

Claims (10)

1. 1. The high-stability electrolyte for the all-vanadium redox flow battery is characterized by comprising an electrolyte stock solution and a stabilizer, wherein the stabilizer comprises a polar solvent and pyrrole, and the polar solvent comprises at least one of acetone and N-methylpyrrolidone; The vanadium concentration in the electrolyte stock solution is 2.0-4.5 mol/L, the sulfate radical concentration is 2-4 mol/L, the chloride ion concentration is 3.2-5.8 mol/L, and the vanadium valence state in the electrolyte stock solution is 2 valence, 3 valence, 4 valence, 5 valence or intermediate valence state.
2. 2. The high-stability electrolyte for the all-vanadium redox flow battery according to claim 1, wherein the stabilizer consists of a polar solvent and pyrrole according to a mass ratio of (2.0-4.3): 1.
3. 3. The high-stability electrolyte for the all-vanadium redox flow battery according to claim 1, wherein the addition amount of the stabilizer is 0.5-5.0wt%.
4. 4. The high-stability electrolyte for the all-vanadium redox flow battery according to claim 1, wherein the polar solvent consists of acetone and N-methylpyrrolidone according to a mass ratio of (3.2-5.6): 1.
5. 5. The high-stability electrolyte for the all-vanadium redox flow battery according to claim 1, further comprising an inorganic additive, wherein the inorganic additive comprises at least one of manganese sulfate, manganese dichloride, chromium sulfate and chromium trichloride, and the addition amount of the inorganic additive is 0.01-0.2wt%.
6. 6. The high-stability electrolyte for the all-vanadium redox flow battery according to claim 5, wherein the inorganic additive consists of chromium trichloride and manganese sulfate according to a mass ratio of (1.5-3.0): 1.
7. 7. The high-stability electrolyte for an all-vanadium redox flow battery according to claim 5, further comprising a synthetic additive, wherein the synthetic additive comprises at least one of polyaminobenzenesulfonic acid, 8-hydroxyquinoline and ammonium phosphate.
8. 8. The high-stability electrolyte for the all-vanadium redox flow battery according to claim 7 is characterized in that the comprehensive additive consists of polyaminobenzene sulfonic acid, 8-hydroxyquinoline and ammonium phosphate according to a mass ratio of 1 (1.7-2.8) (3.0-5.3).
9. 9. The high-stability electrolyte for the all-vanadium redox flow battery according to claim 7, wherein the addition amount of the comprehensive additive is 0.01-1wt%.
10. 10. The method for preparing the high-stability electrolyte for the all-vanadium redox flow battery, as set forth in any one of claims 1 to 9, is characterized by comprising the steps of mixing raw materials of the electrolyte and stirring for 1 to 3 hours to obtain an electrolyte finished product.

Description

High-stability electrolyte for all-vanadium redox flow battery and preparation method thereof Technical Field The application relates to the field of flow batteries, in particular to a high-stability electrolyte for an all-vanadium flow battery and a preparation method thereof. Background In the energy structural transformation of the 21 st century, the utilization of renewable energy is increasingly important. The intermittent and unstable nature of renewable energy sources such as wind, solar, etc. present significant challenges to the stable operation of the grid. In order to solve the problem, a large-scale and long-period energy storage technology is urgent, and among a plurality of energy storage technologies, the all-vanadium redox flow battery has the advantages of high safety, long cycle life, good charge and discharge performance, no cross contamination, quick response, flexible site selection design and the like, and is one of the technical schemes most suitable for large-scale energy storage. The all-vanadium redox flow battery is a redox battery taking vanadium as an active material and in a circulating flowing liquid state. The all-vanadium redox flow battery is an electrochemical energy storage technology based on redox reactions of vanadium ions in different valence states, and belongs to one of the redox flow batteries. Although the all-vanadium redox flow battery has wider application scenes, the application of the all-vanadium redox flow battery in the subzero temperature environment is greatly limited based on the condition that the application environment temperature range of the current vanadium battery industry standard is 0-45 ℃. This is because the electrolyte of the all-vanadium redox flow battery may be solidified in a subzero temperature environment, which greatly affects the working efficiency of the battery. And along with the reduction of temperature, the viscosity of the electrolyte is increased, and meanwhile, the solubility of vanadium ions is reduced, so that the situation of precipitation and crystallization is easy to occur, the working efficiency of the battery is seriously influenced, and even the battery structure is possibly blocked, so that the battery cannot normally run. Therefore, in order to ensure that the all-vanadium redox flow battery can stably operate in a subzero temperature environment, the normal operating temperature range of the all-vanadium redox flow battery is widened, and a high-stability electrolyte for the all-vanadium redox flow battery is necessary to be developed, which is also the key for further perfecting the all-vanadium redox flow battery. Disclosure of Invention The application provides a high-stability electrolyte for an all-vanadium redox flow battery and a preparation method thereof, aiming at solving the problems that the all-vanadium redox flow battery is easy to generate electrolyte solidification and vanadium ion precipitation crystallization in a subzero temperature environment. In a first aspect, the application provides a high-stability electrolyte for an all-vanadium redox flow battery, which adopts the following technical scheme: The high-stability electrolyte for the all-vanadium redox flow battery comprises an electrolyte stock solution and a stabilizer, wherein the stabilizer comprises a polar solvent and pyrrole, and the polar solvent comprises at least one of acetone and N-methylpyrrolidone; The vanadium concentration in the electrolyte stock solution is 2.0-4.5 mol/L, the sulfate radical concentration is 2-4 mol/L, the chloride ion concentration is 3.2-5.8 mol/L, and the vanadium valence state in the electrolyte stock solution is 2 valence, 3 valence, 4 valence, 5 valence or intermediate valence state. By adopting the technical scheme, the polar solvent and the pyrrole are used as the stabilizing agent of the electrolyte system, polar molecules in the polar solvent can interact with hydrogen bonds, so that a hydration hydrogen bond network of the electrolyte system is effectively weakened, the solidifying point of the electrolyte is effectively reduced, and the problems of viscosity increase and vanadium ion precipitation crystallization of the electrolyte system are further solved. Meanwhile, acetone and/or N-methyl pyrrolidone in a polar solvent can be dissolved in an electrolyte system, and a pyrrole component in the stabilizer is slightly soluble in water but can be dissolved in the acetone and/or the N-methyl pyrrolidone, so that the solubility of pyrrole in the electrolyte system is improved, and therefore, the pyrrole exists in a state of partially dissolving and partially floating continuous phases in the electrolyte system. Based on Raoult's law, pyrrole partially dissolved in an electrolyte system can make regular arrangement of solvent molecule lattices difficult, so that the freezing point of the electrolyte is reduced, and pyrrole partially in a continuous phase floating state can prevent solvent molecules