Iron-Air Batteries on Watch List

Metal-air batteries have pure metal anodes, but use ambient air for their cathodes. Their electrolytes are typically aqueous, or aprotic solvents. Their specific capacity and energy density is greater than lithium-ion. Hence they could be candidates for electric vehicles. Interest is growing in iron-air batteries again, and we highlight recent developments here.

How Do Iron-Air Batteries Charge and Discharge?

The metal anode oxidizes as it sheds electrons, when a metal-air battery discharges. Meanwhile a reduction reaction occurs in the air cathode, causing a corresponding gain. Recharging metal-air batteries reverses this process. They have made commercial gains, although technical complications have held them back until now.

More Than One Way to Release Energy in Iron

New Factory for Iron-Air Batteries in Massachusetts

Popular-Mechanics lead with a fascinating story on January 17, 2023. Their reporter Darren Dorf has detected an emerging project in Massachusetts. He says a company is building a large facility there, for manufacturing iron-air batteries. Is this a new ‘iron age’ he asks tongue in cheek.

Each Massachusetts electrochemical iron battery will be ‘about the size of a washer / dryer set’, with an electrolyte surrounding it. Raw iron oxidizes (rusts) naturally as it comes in contact with air. Iron-air batteries use this process to produce energy. Recharging them reverses this process and converts the rust back to iron.

However, This Is Not Entirely New Science

Darren Dorf continues his report by describing how NASA experimented with the technology in the late 1960’s. A report in Research Gate Journal (see link below) recalls there were technical difficulties. Although charge efficiency was 96%, and the idea showed promise for electric vehicles.

The technology is cheap and abundant, which makes a great starting point compared to lithium-ion. We’ve heard indications suggesting using iron-air batteries for slow-charging base load applications. While other, small-scale technologies take care of personal devices. We’ve flagged this idea and will monitor it.