In Search of Lithium-Air Batteries
The Nissan Leaf, an electric car that will go on sale this fall, is priced at $33,000. It's a $16,500 subcompact car that costs double that thanks to a battery estimated to cost $16,500. The eStar, an electric truck being developed by Navistar, will sell for $150,000 because it will tote a battery that costs at least $75,000. Cost isn't the only problem. Both the Leaf and the eStar will be limited to 100 miles of driving on a charge.
Both vehicles are powered by the same kind of batteries that power your laptop, ones that shuttle lithium ions back and forth between two electrodes. The unattractiveness of electric vehicles boils down to two facts: Rechargeable batteries cost a lot and weigh a lot. A lithium-ion battery, at its best, packs 110 watt-hours of energy per pound. Gasoline has 6,000 watt-hours per pound. Now, a gasoline motor is inefficient, discarding 85% of the fuel's energy--losing it to the transmission, wasting it on idling and discharging it as heat. Electric motors waste just 10%, but it still leaves gas with a 9-to-1 weight advantage.
While battery makers are making impressive progress beating down the cost of lithium-ion batteries and improving their performance for cars, battery makers and electric vehicle builders agree that the world needs something new for electric vehicles.
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