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MIT boffins improve lithium-air batteries

by on25 July 2011

Carbon-fibre based electrodes are the way forward
MIT boffins have found a way to improve the energy density of a type of battery known as lithium-air batteries which could result in a device that could potentially pack several times more juice than the traditional lithium-ion method.

Lithium-air batteries are better than lithium-ion batteries because they replace one of the heavy solid electrodes with a porous carbon electrode that stores energy by capturing oxygen from air flowing through the system, combining it with lithium ions to form lithium oxides.

However what Robert Mitchell, a graduate student in MIT's Department of Materials Science and Engineering (DMSE) and co-author of a paper describing the new findings in the journal Energy and Environmental Science has managed to do is create carbon-fiber-based electrodes that are substantially more porous than other carbon electrodes, and can therefore more efficiently store the solid oxidized lithium that fills the pores as the battery discharges.

During discharge, lithium-peroxide particles grow on the carbon fibre and creates an ideal electrode material. The result was a carpet-like material composed of more than 90 percent void space that can be filled by the reactive material during battery operation.
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