A Low-Cost Neutral Aqueous Redox Flow Battery with Dendrite-Free Tin Anode

A neutral aqueous tin-based flow battery is proposed by employing Sn 2+ /Sn as active materials for the negative side, [Fe(CN) 6 ] 3− / Fe(CN) 6 ] 4− as active materials for the positive side, and potassium chloride as the supporting electrolyte, and its overall performances and cost for capacity unit are investigated. Cyclic voltammetry is performed and shows that the Sn 2+ /Sn has outstanding electrochemical behavior. The charging-discharging tests are conducted with the optimized electrolyte composition of 0.2 M [Fe(CN) 6 ] 3− and 3 M KCl. It is shown that the flow cell can reach a high energy efficiency of 80% at 10 mA cm −2 and be stably operated at 40 mA cm −2 . The 120-cycling test shows that the flow cell can be of superior cycling performances, benefitting from the dendrite-free property of tin. Finally, cost analysis further confirms its competitiveness in price, offering a promising future for commercial application. This work not only forms a promising energy storage device with dendrite-free and low-cost benefits, but also provide a deep insight into its overall behavior, which is highly beneficial to the full understanding and further advancement of the proposed neutral tin-iron flow battery.