Sodium Ion Batteries

December 2, 2009

I’ve talked here before about some of the work that is being done to develop new battery technologies, such as rechargeable zinc-air batteries, small nuclear batteries, and lithium-air batteries.  The development of better battery technology is of great interest, because one of the major difficulties with renewable sources of electricity (such as solar  or wind power) is the problem of storing energy that will not be used immediately.  If the storage problem can be overcome, renewable sources could take a much larger role in supplying our energy needs.

The Technology Review is reporting that a start-up firm, 44 Tech, headed by Jay Whitacre, a professor of materials science and engineering at Carnegie Mellon University, has received a $5 million recovery grant from the US Department of Energy to develop a new sodium-ion battery technology.

The startup’s batteries could be not only cheaper but also longer-lasting than existing batteries, Whitacre says. This would make them particularly useful for storing large amounts of electricity cheaply–something that will be essential for making renewable energy the primary source of energy in the U.S., rather than just the supplemental source it is now.

The batteries work in a very similar way to the rechargeable lithium-ion batteries that are widely used in cell phones, laptop computers, and other high-tech gadgets today.  Ions move between the battery’s positive and negative electrodes through an electrolyte.  The sodium-ion technology being developed by 44 Tech has a couple of advantages over existing lithium-ion batteries for power grid use.  Sodium is a much more plentiful element than lithium, meaning that the batteries can be cheaper; and it can be used in lower-voltage cells with a water-based electrolyte (as compared to the organic electrolytes typically used in current batteries), also making for cheaper manufacture.  These characteristics do result in lower energy density because the batteries are heavier, but for stationary installations (as at a power station), the weight penalty is not all that important.

At this point the technology has been demonstrated in the lab; the next step will be attempting to scale it up to make a larger prototype.

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