Researchers have looked into sodium-ion batteries in the past, although typically they have used high voltages and organic electrolytes. Using lower voltages reduces the amount of energy the batteries can store--a problem for electric vehicles, where space and weight are limited. But for stationary applications like storing renewable energy, "it's all about cost," Whitacre says.

Dahn argues that sodium-ion cells shouldn't be developed just for large-scale electricity storage. Higher-voltage sodium-ion batteries may eventually prove a much better solution than lithium-ion batteries for electric vehicles, he says. So far, however, very little research has been done on them relative to lithium-ion batteries. Factors that have kept researchers away--such as the large size of sodium ions and the effect this has on the amount of power the batteries could deliver--have been addressed by recent advances in materials manufacturing. The abundance of sodium could also make these batteries extremely attractive. "It's amazingly more abundant than lithium," Dahn says. "I think it's something that's really important to work on going forward. I hope [the] DOE funds the nonaqueous work, too."

So far, Whitacre's work is at an early stage. He has demonstrated small battery cells in the lab and has filed for a patent covering the technology. He has not disclosed what materials he will use for the electrodes and the electrolyte, and it's too early to provide specific figures about cost, he says. The next steps include making larger prototype batteries. Part of the $5 million award will go to Carnegie Mellon for fundamental research.