IRON AND OXYGEN HOLD THE PROSPECT FOR HIGH CAPACITY BATTERIES

Author
Graham Pitcher

A battery developed by researchers from Northwestern University and the US Argonne National Laboratory uses iron and oxygen to provide a high capacity device with multiple applications.According to the team, the rechargeable lithium-iron-oxide battery can cycle more lithium ions than its lithium-cobalt-oxide counterpart.

“Our computational prediction of this battery reaction is very exciting, but without experimental confirmation, there would be a lot of sceptics,” said Professor Christopher Wolverton. “The fact that it actually works is remarkable.”

The team noted that iron has not been applied successfully in batteries to date and the fact that oxygen is used to help drive the chemical reaction was expected to cause the battery to become unstable.

“In conventional batteries, a transition metal is doing the reaction,” said Prof Wolverton. “Because there is only one lithium ion per one cobalt, that limits of how much charge can be stored. What’s worse is that current batteries … typically only use half of the lithium in the cathode.”

The team has replaced cobalt with iron and forced oxygen to participate in the reaction process. The researchers add that if the oxygen could also store and release electrical energy, the battery would have the ability to store and use more lithium.

Using computational calculations, the team discovered the right balance of lithium, iron, and oxygen ions to allow the oxygen and iron to simultaneously drive a reversible reaction without allowing oxygen to escape.

“Not only does the battery have an interesting chemistry – because we’re getting electrons from both the metal and oxygen – but we’re using iron,” said Prof Wolverton. “That has the potential to make a better battery that is also cheap.”

Importantly, the battery – said to be fully rechargeable – starts with four lithium ions, instead of one and the opportunity to cycle all four back and forth by using both iron and oxygen to drive the reaction is described by Prof Wolverton as ‘tantalising’.

“Four lithium ions for each metal -- that would change everything,” he said. “That means your phone could last eight times longer or your car could drive eight times farther. If battery-powered cars can compete with or exceed gasoline-powered cars in terms of range and cost, that will change the world.”