An electrochemical process for producing and recycling VRFB electrolytes

Electrochem Technologies & Materials Inc. (Montreal, Canada; www.electrochem-technologies.com) has recently patented its process for the production and recycling of all vanadium electrolytes (VE) used in vanadium redox flow batteries (VRFBs). This electrochemical technology offers a sound and profitable alternative to the chemical production of electrolyte, says company president, François Cardarelli. Industrially, all vanadium sulfates electrolyte solutions are prepared chemically by reacting high-purity vanadium pentoxide (V2O5) as starting material with high-purity sulfuric acid. However, the chemical process requires the use of a reducing agent that allows the reduction of the barely soluble peroxovanadium (VO2+) cation into highly soluble vanadyl (VO2+) cation and, to a lesser extent, V3+ cation to reach the targeted molarities. The proper reducing agent used is either an organic compound, such as oxalic acid, or an inorganic reagent, such as vanadium (III) oxide (V2O3), sulfur or gaseous SO2. During the chemical processes, the dissolution reaction kinetics are driven by temperature and the concentrations of both H2SO4 and the reducing agent. As a result, the production rate is not easily adjustable, Cardarelli says. By…