By Ken Bensinger

Los Angeles Times

Chances are the same kind of battery that twice caught fire in Boeing 787 Dreamliners in recent weeks is in your pocket at this very moment.

Lithium ion batteries, small and powerful, have become the electricity storage device of choice. They are everywhere--in cellular phones, laptops, power tools, even cars. They allow us to talk, email and drill longer than ever possible in the past.

But the incidents that led to the grounding of the 787 fleet worldwide, and the decision by Boeing on Friday to temporarily halt all deliveries of the plane, have highlighted a troubling downside of these energy-dense dynamos: their tendency to occasionally burst into flames.

With investigators now working to determine the cause of the incidents, one on a Dreamliner on a Boston runway, the other forcing an emergency landing of a 787 in western Japan, the larger question of lithium ion safety has snapped into focus.

"Every battery can burn, and every battery can be flammable," said Mike Eskra, a Milwaukee-based battery development scientist who also works as a battery fire investigator for insurers. "But lithium ion batteries are more dangerous because they store more energy. It's like a firecracker instead of a stick of dynamite."

The casualty list is long. In recent years, tens of thousands of laptop batteries have been recalled due to the risk of fire or explosion. The 400-pound lithium ion battery on a Chevrolet Volt, General Motors' cutting-edge electric car, burst into flames seemingly spontaneously while parked in 2011.

Thanks to their chemistry, the rechargeable batteries can store as much energy as a nickel metal hydride pack that's 50 percent heavier, while charging and discharging faster than other battery types. That has made them attractive for military applications such as the B-2 bomber and also for use on the International Space Station and the Mars Rover.

Lithium ion batteries enabled Boeing to swap out heavy hydraulic systems in the airframe for lightweight electronics and electric motors to operate systems like wing de-icers. That's a key reason the Dreamliner burns 20 percent less fuel than other wide-body aircraft.

The weight and power savings are exactly what made lithium ion batteries popular in other applications. In excess of 95 percent of mobile phone batteries worldwide are lithium ion, and without lithium ion, laptops couldn't run anywhere near as long as they do without a recharge.

But lithium ion also has downsides. The batteries tend to have shorter life spans than older, more proven battery technologies. And although the price is falling, lithium ion technology is still more expensive than other batteries.