Scaled-up aqueous redox flow battery using anthraquinone negalyte and vanadium posilyte with inorganic additive

In this study, one kilowatt aqueous redox flow battery (ARFB) using anthraquinone-2,7-disulfonic acid (2,7-AQDS) and vanadium oxide sulfate (VOSO4) as active materials for negalyte (negative electrolyte) and posilyte (positive electrolyte) is successfully accomplished. Then, manganese sulfate (MnSO4) is further included in negalyte to increase reactivity of active materials and to suppress their crossover by controlling their osmotic pressure. This binary effects of MnSO4 are predicted by density functional theory and reduction in concentration gap. The decrease in energy band gap of 2,7-AQDS with MnSO4 facilitated electron transfer rate. Anodic and cathodic diffusion coefficient and reaction rate constant are also improved. More specifically, with adoption of MnSO4 additive, energy efficiency and capacity retention rate of ARFB single cells operated with MnSO4 additive are improved from 79.1 to 83.9% at the current density of 40 mA cm−2 and from 82 to 88% at the current density of 80 mA cm−2 after 100 cycles. Based on that, ARFB stack using 2,7-AQDS and VOSO4 with MnSO4 additive is prepared and this ARFB stack exhibits a high power of 1.15 kW.