A highly concentrated vanadium protic ionic liquid electrolyte for the vanadium redox flow battery

A protic ionic liquid is designed and implemented for the first time as a solvent high energy density vanadium redox flow battery. Despite being less conductive than standard aqueous electrolytes, it thermally stable on 100 °C temperature window, chemically at least 60 days, equally viscous dense with typical solvents most importantly able to solubilize 6 mol L-1 sulfate, thus increasing VRFB by factor of 2.5. Electrochemical measurements revealed quasi-reversible transitions both catholyte anolyte 25 while proof-of-concept cell proposed electrolyte was tested total 150 cycles °C, showing an open circuit potential 1.39 V coulombic efficiencies 65% 93%, respectively. What’s more, battery can be cycled 45 good thermal stability. This study underlines new route improve energy-to-volume ratio storage system.