Low Cost 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 technology 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 in the range 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 RFB with low cost and high energy density will be presented. In particular, inorganic electrolytes based on high soluble salts have been developed, achieving a charge density of 55-70 Wh/l. We report the use of a new electrolyte as mid acidic solution for zinc electrodeposition, which can not only improve the electrolyte conductivity but also reduce the risk of zinc dendritic growth. Moreover, the developed electrolytes have been characterized by means of cyclic voltammetries in order to investigate the effect of different additives on the electrochemical properties. The combination of high energy efficiency of the Zn-Fe RFB, in the order of 70- 75% at 25 mAcm-2, 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. References P. Alotto, M. Guarnieri, and F. Moro. Renewable and Sustainable Energy Reviews (2014) 29, 325-335.A. Z. Weber, M.M. Mench,, J.P. Meyers, P.N. Ross, J.T. Gostick and Q. Liu. Journal of Applied Electrochemistry (2011), 41(10), 1137.G. Kear, A.A Shah, and F.C. Walsh. International journal of energy research, (2012), 36(11), 1105-1120.C. Ding, H. Zhang, X. Li, T. Liu, and F. Xing. The Journal of Physical Chemistry Letters, (2013), 4(8), 1281-1294.C- Xie, Y. Duan, W. Xu, H. Zhang, and X Li. Angewandte Chemie International Edition, (2017) 56(47), 14953-14957.S. Selverston, R. F. Savinell, and J. S. Wainright. Journal of The Electrochemical Society (2017) 164(6), A1069-A1075.