It is the quickest electric motorcycle in the world. On a popular YouTube video, the black dragster cycle nearly disappears in a cloud of smoke as the driver does a "burn-out," spinning the back wheel to heat it up. As the smoke drifts away, the driver settles into position and hits a switch, and the bike surges forward, accelerating to 60 miles per hour in less than a second. Seven seconds later it crosses the quarter-mile mark at 168 miles per hour--quick enough to compete with gas-powered dragsters.

What powers the "Killacycle" is a novel lithium-ion battery developed by A123 Systems, a startup in Watertown, MA--one of a handful of companies working on similar technology. The company's batteries store more than twice as much energy as nickel-metal hydride batteries, the type used in today's hybrid cars, while delivering the bursts of power necessary for high performance. A radically modified version of the lithium-ion batteries used in portable electronics, the technology could jump-start the long-sputtering electric-vehicle market, which today represents a tiny fraction of 1 percent of vehicle sales in the United States. A123's batteries in particular have attracted the interest of General Motors, which is testing them as a way to power the Volt, an electric car with a gasoline generator; the vehicle is expected to go into mass production as early as 2010.