Researchers at the Massachusetts Institute of Technology have unveiled a breakthrough iron-air battery design that could fundamentally change the economics of long-duration energy storage. Published this week in the journal Nature Energy, the study describes a novel electrode architecture that enables iron-air cells to achieve round-trip efficiency of 72% while maintaining stable performance over 3,000 cycles.
Iron-air batteries work by reversibly rusting and un-rusting iron, using oxygen from the air as a reactant. The technology has been pursued for decades due to the extraordinary abundance and low cost of iron, but previous designs suffered from poor efficiency and rapid degradation. The MIT team solved these problems by developing a novel bifunctional catalyst and a specially engineered porous iron electrode that prevents the mechanical stresses that typically cause cell failure.
The projected cost is striking. At scale, the team estimates the battery could store energy at a levelized cost of just $5-8 per kilowatt-hour, compared to $140-200 for current lithium-ion systems. This dramatic cost advantage makes it economically viable to store renewable energy for days or even weeks, addressing one of the biggest challenges in transitioning to a fully renewable grid.
Professor Yet-Ming Chiang, who led the research, noted that the materials used are among the most abundant on Earth. Iron is the fourth most common element in the Earth crust, and the alkaline electrolyte uses potassium hydroxide, a widely available industrial chemical. This means the technology could scale to terawatt-hour levels without encountering the supply chain bottlenecks that plague lithium and cobalt.
Several companies are already working to commercialize iron-air technology. Form Energy, a startup co-founded by Chiang, has broken ground on a manufacturing facility in West Virginia and expects to deliver its first commercial systems by late 2026. The company has secured over $800 million in funding from investors including Breakthrough Energy Ventures and ArcelorMittal.
