Zinc-Iron Rechargeable Flow Battery with High Energy Density

Abstract

In current research, electrochemical energy storage systems have gaining interest because they constitute an essential element in the development of sustainable energy technologies [1,2]. Among them, rechargeable flow batteries (RFBs) are one of the most promising technologies for the integration in grid-connected electricity, especially if combined with unpredictable and intermittent renewable energy sources, due to their high efficiency, power/energy independent sizing and room temperature operation [3]. At the moment, among all RFBs systems, the most investigated and advanced technology is the vanadium based RFB, characterized by an energy efficiency equal to 80% and energy density ranging 15-45 Wh/l [4]. However, nowadays the main bulk of research is focused on finding an economically convenient and technically competitive flow battery chemistry, able to ensure long lifetime and high energy efficiency [5,6]. In this study, a zinc-iron RFBs based on sulfate and sulfamate electrolytes will be presented, discussing the achievement of a charge density in the range 30-70 Wh/l. The combination of high energy efficiency of the Zn-Fe RFB with its ability to withstand a large number of charge/discharge cycles and the low cost, makes this battery system suitable for energy storage applications.