Iron-Based Cathodes: The Future of Lithium-Ion Batteries

The breakthrough by Oregon State University's team demonstrates that iron can achieve higher energy densities, making it a promising candidate for sustainable battery solutions that could revolutionize the electric vehicle industry and broader energy storage applications.

The development of iron-based cathode materials marks a pivotal advancement in lithium-ion battery technology, offering a greener and more cost-effective alternative to traditional cobalt and nickel-based cathodes. Iron—abundant and inexpensive—can significantly reduce production costs and environmental impact. This innovation addresses the critical issues of resource scarcity and safety associated with other materials such as cobalt and nickel.

Advantages of iron-based cathode materials

Iron-based cathode materials offer significant advantages for lithium-ion batteries. They are more cost-effective due to the abundance and low price of iron compared to cobalt and nickel. These materials enhance safety by providing greater thermal and chemical stability, reducing the risk of overheating and fires. Additionally, they promote sustainability by minimizing environmental and ethical concerns associated with cobalt and nickel mining. Iron-based cathodes also offer long cycle life and robust performance, making them ideal for applications requiring durable and reliable energy storage. This combination of affordability, safety, and sustainability positions iron-based cathodes as a transformative solution in battery technology.

Related:‘One-Pot-Process’ Provides Cleaner Manufacturing of Cathodes

A breakthrough for  iron-based cathode materials

The findings are hoping to spark a green battery revolution. The results of the collaboration co-led by an Oregon State University chemistry researcher were published today in Science Advances and are important for multiple reasons, Oregon State’s Xiulei “David” Ji notes.

“We’ve transformed the reactivity of iron metal, the cheapest metal commodity,” he stated. “Our electrode can offer a higher energy density than the state-of-the-art cathode materials in electric vehicles. And since we use iron, whose cost can be less than a dollar per kilogram – a small fraction of nickel and cobalt, which are indispensable in current high-energy lithium-ion batteries – the cost of our batteries is potentially much lower.”

At present, the cathode represents 50% of the cost in making a lithium-ion battery cell, Ji declared. Beyond economics, iron-based cathodes would allow for greater safety and sustainability, he added. According to Ji, in a matter of a couple of decades, predicted shortages in nickel and cobalt will put the brakes on battery production as it’s currently done.

Related:Building Better Cathodes Without Cobalt

In addition, those elements’ energy density is already being extended to its ceiling level – if it were pushed further, oxygen released during charging could cause batteries to ignite – plus cobalt is toxic, meaning it can contaminate ecosystems and water sources if it leaches out of landfills.

“Our iron-based cathode will not be limited by a shortage of resources,” stated Ji, explaining that iron, in addition to being the most common element on Earth as measured by mass, is the fourth-most abundant element in the Earth’s crust. “We will not run out of iron till the sun turns into a red giant.”

Ji and collaborators from multiple universities and national laboratories increased the reactivity of iron in their cathode by designing a chemical environment based on a blend of fluorine and phosphate anions – ions that are negatively charged.

The blend, thoroughly mixed as a solid solution, allows for the reversible conversion – meaning the battery can be recharged – of a fine mixture of iron powder, lithium fluoride and lithium phosphate into iron salts.

“We’ve demonstrated that the materials design with anions can break the ceiling of energy density for batteries that are more sustainable and cost less,” Ji said. “We’re not using some more expensive salt in conjunction with iron – just those the battery industry has been using and then iron powder. To put this new cathode in applications, one needs to change nothing else – no new anodes, no new production lines, no new design of the battery. We are just replacing one thing, the cathode.”

Ji highlighted that storage efficiency still needs to be improved. Right now, not all of the electricity put into the battery during charging is available for use upon discharge. Ji expects that when those improvements are made, the result will be a battery that works much better than the ones currently in use while costing less and being greener.

“If there is investment in this technology, it shouldn’t take long for it to be commercially available,” Ji continued. “We need the visionaries of the industry to allocate resources to this emerging field. The world can have a cathode industry based on a metal that’s almost free compared to cobalt and nickel. And while you have to work really hard to recycle cobalt and nickel, you don’t even have to recycle iron – it just turns into rust if you let it go.”

As research continues to refine and optimize these materials, iron-based cathodes are poised to play a crucial role in the future of electric vehicles and renewable energy storage, driving a more sustainable and cost-effective battery industry.