A better, cheaper battery
Through computational calculations, Wolverton and Yao discovered a formulation that works reversibly. First, they replaced cobalt with iron, which is advantageous because it's among the cheapest elements on the periodic table. Second, by using computation, they 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 gas 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," Wolverton said. "That has the potential to make a better battery that is also cheap."
And perhaps even more importantly, the fully rechargeable battery starts with four lithium ions, instead of one. The current reaction can reversibly exploit one of these lithium ions, significantly increasing the capacity beyond today's batteries. But the potential to cycle all four back and forth by using both iron and oxygen to drive the reaction is tantalizing.
"Four lithium ions for each metal – that would change everything," Wolverton said. "That means that 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."
Wolverton has filed a provisional patent for the battery with Northwestern's Innovation and New Ventures Office. Next, he and his team plan to explore other compounds where this strategy could work.