An optimistic approach on flow rate and supporting electrolyte for enhancing the performance characteristics of Zn-Br2 redox flow battery

Abstract

Herein for the first time, we have successfully demonstrated the influence of flow rate on the polarization effect caused by the sluggish kinetics of Br−/Br2 redox couple in zinc-bromine redox flow battery (ZBRFB). Besides, the effect of perchloric acid (HClO4) on Br−/Br2 redox reaction has also been explored. The optimized electrolyte flow rate condition shows significant improvisation on the round-trip efficiency (> 95%) due to the balanced kinetics. Further, the double-layer formation was substantially minimized with the help of HClO4 as evidenced by cyclic voltammetry studies. The electrode kinetics towards Br−/Br2 also was enhanced by increasing the concentration of HClO4. The enhanced voltage efficiency (~85%) of the flow cell employing HClO4 as a supporting electrolyte is mainly accredited to the balanced conductivity of the redox electrolyte. Moreover, optimized flow cell design exhibits good cycle life and improved ohmic region over the prolonged cycle studies in comparison. Thus, the optimistic flow rate and the selection of such an efficient electrolyte additive can be proficient candidates for improving the zinc-bromine battery performances.