Researchers from IIT Madras have successfully fabricated a rechargeable iron-ion batteries for the first time.
- IIT Madras researchers have used mild steel as the anode to achieve the feat.
- Iron-ion batteries are cost-effective and can store high amounts of energy.
- The lithium-ion is the charge carries in lithium-ion batteries that are widely in use now.
- The invention comes at a time when the world is moving towards adopting electric vehicles which need cheaper batteries.
- Also, lithium reserves are limited when compared to iron reserves and hence the inventions assume significance.
- The IIT Madras team has demonstrated the performance of Fe2+ ions battery for 150 cycles of charging and discharging.
- It has displayed good stability with 54% capacity retention at the end of 50 cycles.
- With the iron ion battery, when fabricated in controlled conditions, 220Wh per kg of energy can be drawn from the battery. This is 55-60% of the lithium-ion battery’s performance. The lithium-ion battery has an energy density of around 350Wh per kg.
- As per the researchers, the battery can be fabricated under controlled conditions and also at higher densities so that energy can be drawn at faster rates.
Properties of Fe2+
- Iron ion has higher redox potential than lithium-ion.
- The radius of the Fe2+ ion is the same as lithium-ion.
- Pure iron is not favourable for making the battery as removal of iron ions from the anode and reinsertion is an essential mechanism that does not work in pure iron.
- But the mild amount of carbon in mild steel allows this process.
- Iron is also stable during the charging process and avoids short-circuiting of the batteries.
- The cathode used in the iron ion battery is vanadium pentoxide. It has a layered structure with very large spaces between the layers. The spacing allows for an iron ion to move in move back to the anode easily.
- The electrolyte used is also different. The researchers used ether-based electrolyte which contains dissolved iron perchlorate. It acts as a perfect iron conducting medium between anode and cathode.
- Currently, the researchers are experimenting on different metal oxides to make more iron ions bind to the cathode so that more energy can be stored. And also, looking to improve the stability of the battery.
The invention is timely as the government is looking to push electric vehicles in the country. The new battery when available commercially will reduce imports of lithium-ion batteries and act as a cheaper alternative thereby reducing the overall costs of an EV making it more attractive for buying.