Precipitation/Dissolution of Supersaturated V(III) Sulfate Electrolytes

Abstract

Redox flow batteries (RFBs)-based storage systems have the unique feature of separate power generating and energy storage units that can be individually sized. RFBs can be used for days-long energy storage, but because of the low solubility of most ions and molecules in both aqueous and non-aqueous solvents,[1,2] scaling these RFB systems for days-long applications requires significant storage volume and floor area. Our team has been working on a new storage method that significantly increases the energy storage density while still maintaining the traditional flow battery design.[3] This method involves storing the reactants as both soluble ions and an undissolved solid form, only the liquid containing soluble ions is circulated through the batteries. To achieve this, a solid form of Vanadium salt must be precipitated within the storage tanks, necessitating a study on the precipitation and dissolution of various vanadium salts. Past work has been done by our group on the Vanadium (IV/V) solution,[4] we now focus on the Vanadium (II/III) solution. This presentation will discuss the production of Vanadium (III) sulfate salt electrolytes, and the precipitation rate of said salt at oversaturation.