Low loading of Pt@Graphite felt for enhancing multifunctional activity towards achieving high energy efficiency of Zn–Br2 redox flow battery

Abstract

Polyhalides based hybrid redox flow batteries are highly appropriated for long term stationary charge storage applications due to their high practical energy density, long cycle life, low cost, etc. Among various metal-halide redox flow batteries, zinc-bromine redox flow battery system received much attention due to its reasonable cell voltage, energy density and life-time. However, the poor kinetics of bromine/bromide redox reaction at the electrodes and bromine vapour formation during the charge process are the major issues associated with this flow system. In the present work, low loading of platinum is used as electrocatalyst for improving the Br2/Br-reaction kinetics where platinum particles are deposited on the graphite felt using pulsed laser deposition. Platinum decorated graphite felt is investigated as an active electrode material in the positive compartment of this flow system to study the improvement in the reaction kinetics of Br2/Br− redox couple reaction. This approach is highly influenced in bromine/bromide redox reaction kinetics, as a result, avg. Coulombic efficiency of 99.96% and ever best avg. energy efficiency of ~88% is observed for the zinc-bromine based flow cell tested at 50 mA cm−2. Thus, graphite felt having low loading platinum is considered as a potential candidate for enhancing the Br2/Br-kinetics at any given condition.