Pump-less, free-convection-driven redox flow batteries: Modelling, simulation, and experimental demonstration for the soluble lead redox flow battery

A novel concept of pump-less, free-convection-driven redox flow battery (RFBs) is proposed. The concept is applicable to hybrid redox flow batteries in general. The concept is demonstrated for soluble lead redox flow battery (SLRFB) by developing a mathematical model. The model accounts for reaction kinetics at electrodes and ion transportation in electrolyte domain of the battery. It predicts existence of induced free convection which not only help overcome ion transfer resistance at electrode surfaces but also couples electrode compartment and reservoir compartment of the battery hydro-dynamically and capacitively. It also predicts electrode kinetics and ion transfer rate as cell voltage controlling mechanisms. Finally, cyclic performance of the pump-less SLRFB is demonstrated experimentally. The experiments shows faradaic efficiency and energy efficiency to be (similar to)93% and( )(similar to)65% respectively, in par with conventional pump-based SLRFB. The concept is also extended to other hybrid RFBs and their limiting performances are predicted.