IBM’s Breathing Battery

April 22, 2012

I’ve written here several times before about the importance of better battery technology to the effort to use more energy from renewable sources (such as wind or solar power), and to the development of better electric vehicles.  While autos like the Toyota Prius, which have hybrid gasoline-electric power, have been reasonably successful (helped, of course, by tax and other incentives), the development of all-electric vehicles has been held back by the relatively low power to weight ratio of current batteries.  Gasoline’s big advantage as a vehicle fuel is that it has a high energy density, the amount of power that can be generated per kilogram of fuel.

Back in 2009, IBM launched a research project, called Battery 500, aimed at developing new battery technology that would allow an electric vehicle to travel 500 miles on a single charge.   The project cites consumer surveys that indicate that “range anxiety”, the fear of being stranded without power, is a significant obstacle to consumer acceptance of all-electric vehicles.

Electric cars today typically can travel only about 100 miles on current battery technology, called lithium-ion (LIB). LIB technology stands little chance of being light enough to travel 500 miles on a single charge and cheap enough to be practical for a typical family car.

Now, according to an article at Wired, IBM has demonstrated a prototype lithium-air battery that the company believes has the potential to power a car for 500 miles.   (The ExtremeTech site also has an article on this development.)  The idea of a lithium air battery is not new; one of its key attractions is that, because one of the reactants, air, is taken in from the outside rather than having to be built into the battery, weight and size are reduced.  In the approach developed by IBM, oxygen from the air is taken into tiny openings in the battery cell, about 1 angstrom (10-10 meter) across.  The oxygen then reacts with lithium ions on the battery cathode, producing lithium peroxide and electrons, and thus electric current.  Charging the battery reverses the chemical reaction, releasing oxygen back into the air.  Theoretically, this technology should be able to achieve an energy density of about 12 kWh/kg, roughly 15 times that of lithium-ion batteries.

There is considerable work still to be done to turn this development into a practical product; some of that will probably decrease the energy density somewhat.  Nonetheless, this is a significant step forward, because it has the potential of achieving an energy density at least roughly comparable to gasoline.

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