Scientists discover iron as key to cheaper, greener batteries

A collaboration co-led by Oregon State University chemistry researcher David Ji is hoping to spark a green battery revolution by showing that iron instead of cobalt and nickel can be used as a cathode material in lithium-ion batteries. Credit: Xiulei "David" Ji, Oregon State University.

What if a common element, instead of rare and expensive ones, could revolutionize electric car batteries?

Researchers, including an Oregon State University chemistry team, have found that iron can replace cobalt and nickel as a cathode material in lithium-ion batteries.

Their findings, published in Science Advances, could lead to cheaper and more sustainable batteries.

“We’ve transformed the reactivity of iron, the cheapest metal commodity,” said Xiulei “David” Ji from Oregon State.

“Our electrode offers higher energy density than current materials used in electric vehicle batteries.

Plus, since we use iron, which costs less than a dollar per kilogram compared to nickel and cobalt, our batteries could be much cheaper.”

Currently, the cathode makes up 50% of the cost of a lithium-ion battery cell. Beyond cost, iron-based cathodes are safer and more sustainable. As the demand for lithium-ion batteries increases, so does the demand for nickel and cobalt.

In a few decades, shortages of these elements could slow battery production. Additionally, pushing their energy density further could cause safety issues, and cobalt is toxic and harmful to the environment.

A battery stores energy chemically and converts it to electricity to power vehicles, phones, laptops, and other devices. It consists of two electrodes—an anode and a cathode—along with a separator and an electrolyte.

During discharge, electrons flow from the anode to the cathode through an external circuit. In a lithium-ion battery, lithium ions move through the electrolyte from the anode to the cathode during discharge and back again during recharging.

“Our iron-based cathode won’t face resource shortages,” Ji explained. “Iron is the most common element on Earth and the fourth-most abundant in the Earth’s crust. We won’t run out of iron until the sun becomes a red giant.”

Ji and his team enhanced iron’s reactivity in their cathode by creating a chemical environment with a blend of fluorine and phosphate anions, which are negatively charged ions.

This blend, mixed as a solid solution, allows for the reversible conversion of iron powder, lithium fluoride, and lithium phosphate into iron salts. This means the battery can be recharged.

“We’ve shown that using anions can break the energy density ceiling for batteries, making them more sustainable and cheaper,” Ji said.

“We’re not using expensive salts with iron—just the usual ones used in the battery industry, plus iron powder. To use this new cathode, no other changes are needed—no new anodes, production lines, or battery designs. We’re just replacing one component, the cathode.”

Ji noted that while storage efficiency still needs improvement, these advancements are expected soon. This will result in better-performing, cheaper, and greener batteries.

“If there’s investment in this technology, it could be commercially available quickly,” Ji said. “We need industry visionaries to support this emerging field.

The world can have a cathode industry based on a metal that’s nearly free compared to cobalt and nickel. Plus, iron doesn’t need intensive recycling—it just turns into rust if left alone.”

The research was co-led by Tongchao Liu from Argonne National Laboratory, with contributions from scientists at Vanderbilt University, Stanford University, the University of Maryland, Lawrence Berkeley National Laboratory, and SLAC National Accelerator Laboratory.