Realizing highly efficient energy retention of Zn–Br2 redox flow battery using rGO supported 3D carbon network as a superior electrode

Zinc–Bromine redox flow battery (Zn–Br2 RFB) is one of the most promising aqueous metal hybrid flow batteries used to store high energy in mega scale. This aqueous system provides high cell voltage with high practical energy density over the other redox flow systems. Conversely, poor reversibility of bromide/bromine redox couple strictly affects cell performances such as rate capability, cell efficiency and cycle life. In the present work, the rate capability is enhanced to 80 mA cm−2 by improving the bromine reversibility in the positive electrode. First time, reduced Graphene Oxide (rGO) is employed to improve the bromine kinetics in the Zn–Br2 redox flow battery. The electrochemical analysis showed highly renovated bromine kinetics with less peak separation potential (103 mV) and very closer onset potentials (anodic reaction: 0.92 V & cathodic reaction: 1.08 V). Moreover, the obtained anodic (Ia) and cathodic (Ic) peak current ratio (Ia/Ic) 0.83 indicates the improved reversibility of bromine reactions on rGO supported 3D carbon felt electrodes. Importantly, the cell showed increased energy efficiency of 80.75% for the rGO supported electrode based flow system over the studied cycle range. Thus, the rGO based electrode materials have fascinated more interest as an efficient electrocatalyst for Zn–Br2 RFB development.