GM has lithium-ion batteries for hybrids figured out

— -- General Motors will begin mass production in 2010 of hybrid vehicles that use lithium-ion batteries and, in many cases, turbocharged small-displacement gasoline engines. The combination will let GM use the hybrid system on any size vehicle it produces.

It's a sign that lithium-ion batteries, now common in laptops and cellphones, may finally be ready for prime time in vehicles. Automakers have been striving to develop the battery, because it is better-suited to power hybrids — and eventually fully electric vehicles — than the current nickel-metal-hydride batteries.

Lithium-ion batteries have some drawbacks. They don't work well in very cold weather; they generate heat and need a way to be cooled; and they cost more than other batteries. But they are lighter and smaller for their power, so carmakers like them because they don't have to waste a lot of space on a huge battery.

The lithium-ion battery GM will use in its second generation of hybrids is a quarter the size of the nickel-metal-hydride batteries it now is using.

"We need a battery that is very compact and is very light," says Stephen Poulos, global chief engineer of GM's hybrid systems. "Lithium ion is a great enabler for that."