The great battery race
Dramatic developments in stored-power technology make electric cars more viable than ever.

Aside from escalating gas prices and concerns about global warming, the changing attitudes toward hybrids is being driven by rapid developments in the batteries used to power them. Not long ago, batteries seemed trapped in the 19th century, a mature technology that wasn't progressing very quickly. But both established battery makers and ambitious startups are pushing battery development at once unimaginable speeds.

Replacing nickel-metal hydride batteries, the kind that are used in the Toyota Prius, are lithium-ion batteries, first designed for such applications as laptop computers and cell phones. Lithium-ion batteries provide twice the power, energy density, and cycle life of nickel metal-hydride, but less than half the weight and size, and half the cost. read more at cnn.com