An aqueous alkaline battery consisting of inexpensive all-iron redox chemistries for large-scale energy storage

In this work, an iron-based alkaline battery using the same redox-active element featuring different coordination chemistries is developed and tested. The battery achieves a significantly low active material cost per kilowatt hour ($22 kW h(-1)) due to the inherently inexpensive price and availability of iron oxide and iron ferricyanide, particularly when compared with state-of-the-art vanadium redox flow batteries ($118 kW h(-1)) or the commercialized nickel cadmium battery ($51 kW h(-1)). Experimental results show that the present battery creates an equilibrium cell potential of 1.2 V and its coulombic efficiency reaches as high as 99% at a current density higher than 4 mA cm(-2). Moreover, the energy efficiency can be maintained above 76% and the capacity decay rate is only 0.15% per cycle at a current density of 2 mA cm(-2) over 150 cycles. With these advantages, the battery offers a promising solution for low-cost energy storage applications.