A Rechargeable, Aqueous Iron Air Battery with Nanostructured Electrodes Capable of High Energy Density Operation

Abstract

In order to decrease the global dependence on fossil fuels, high energy density, rechargeable batteries with high charge capacity are required for mobile applications and efficient utilization of intermittent sources of renewable energy. Metal-air batteries are promising due to their high theoretical energy density. In particular, the iron-air battery, with a maximum specific energy output of 764 W h kg−1Fe, represents a low cost possibility. This paper considers an iron-air battery with nanocomposite electrodes, which achieves an energy density of 453 W h kg−1Fe and a maximum charge capacity of 814 mA h g−1Fe when cycled at a current density of 10 mA cm−2, with a cell voltage of 0.76 V. The cell was manufactured by 3D printing, allowing rapid modifications and improvements to be implemented before an optimized prototype can be manufactured using traditional computer numerical control machining.

Development of the Iron Electrode for Utility Scale Energy Storage

“…Differences between the actual cell voltage and the theoretical cell voltage occur due to factors including internal resistance and the overpotential required for key reactions to occur. For example, in the above system solubility of reaction intermediaries result in a high overpotential [29].…”

“…Air electrodes typically employ a metal foil negative electrode and an external positive electrode which functions using oxygen in ambient air [18]. The potential for an exceptionally high energy density battery drives this research, although Figueredo-Rodríguez et al note that air electrodes still have complex challenges associated with them [29]. Metal air cells with a variety of negative electrodes are possible: Li, Ca, Mg, Al, Zn and Fe, some of which suffer from dendrite formation which could potentially limit cell lifetime [29].…”

“…The potential for an exceptionally high energy density battery drives this research, although Figueredo-Rodríguez et al note that air electrodes still have complex challenges associated with them [29]. Metal air cells with a variety of negative electrodes are possible: Li, Ca, Mg, Al, Zn and Fe, some of which suffer from dendrite formation which could potentially limit cell lifetime [29]. These can use either a third electrode or a bifunctional electrode to sustain both oxygen reduction and evolution [26].…”

“…These can use either a third electrode or a bifunctional electrode to sustain both oxygen reduction and evolution [26]. Iron air cells offer several advantages over other metal air chemistries due to potential for low cost, long cycle life and freedom from dendrites due to insolubility of the reaction intermediates in the electrolyte [29], [52], [53]. Whilst typically, it is the air electrode which requires further development to make a metal air system viable, development of a negative electrode, such as the iron electrode, would improve the future performance of a metal air chemistry.…”

“…'Nanostructured' electrodes have been researched due to potential for higher power as well as increased utilization resulting in increased capacity [20], [29], [102]- [104].…”