A Rechargeable battery that uses iron ion instead of lithium has been produced by researchers at the Indian Institute of Technology, Madras (IIT-M). The battery makes use of anode made of low-carbon steel rather than pure iron, a cathode made of vanadium pentoxide and iron chlorate as the electrolyte.
The iron ion battery has better storage capacity and is cost-effective. The battery is safe to use as iron cannot produce dendrites thereby preventing short circuits. Moreover, in order to draw energy at a more accelerated rate, the battery can be cycled at high current densities.
“Compared to other metals, iron is cheaper, has a smaller ionic radius and favorable redox potential. Since these benefits are overlooked, the potential use of iron in rechargeable metal-ion battery has not been realized yet”, said the team of the Physics Department.
The team tried using an ether-based electrolyte containing dissolved iron perchlorate with which they got the best results as iron perchlorate behaves like an ion-conducting medium between the anode and cathode.
“The redox potential of iron ion is higher than lithium-ion, and the radius of the Fe2+ ion is nearly the same as that of the lithium-ion, These two favorable properties of iron have been overlooked for so many years and that’s the reason why we don’t have iron ion rechargeable batteries.” the team claims.
The newly developed batteries will, however, require further optimization and testing as it is just capable of 150 cycles of charging and discharging. The energy density of the iron ion battery is 220 Wh per kg which is 55-60% of lithium-ion battery’s performance.
“We are trying out different metal oxides to increase the number of iron ions that can bind to the cathode. When more iron ions bind to the cathode, more energy can be stored in the battery leading to improved performance,” says Ms. Piriya.