Are Your Rechargeable Batteries Safe?

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From the eco-friendly Chevy Volt to high-tech Boeing Dreamliner 787, recent high-profile battery fires are focusing attention on the risks and rewards of one of our most ubiquitous technologies: rechargeable lithium-ion batteries.

Not only do they run nearly all of our laptops and cellphones, but they are now increasingly used to power planes, trains and automobiles. Experts say demands to make vehicles lighter and more fuel-efficient are creating bigger demands on lithium-ion batteries, and that, in turn, is exposing them to risks of overheating. An episode with an overheating battery has now grounded Boeing’s entire fleet of new Dreamliner 787 aircraft.

A smoking lithium-ion battery forced pilots to make an emergency landing of an All Nippon Airways 787 last week, while a second battery inside a Japan Airlines 787 parked at Boston’s Logan Airport ignited on Jan. 7. Japanese investigators said Wednesday that the All Nippon battery was not overcharged, something that many experts originally thought could have been the problem, so the cause is still unclear.

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Experts say the fire could have something to do with wiring or how the batteries were connected to remove heat that's generated during recharging.

“It’s a multidimensional problem,” said Venkat Srinivasan, director of the battery research program at Lawrence Berkeley Laboratory. “It’s suggesting that something happened outside the battery that failed.”

Nearly 20 years ago, a rash of exploding laptops almost derailed the rechargeable battery industry, but engineers figured out how to devise a cut-off switch that stopped the current after reaching a certain point. Today, scientists and engineers are working on alternatives to lithium-ion batteries that can both last longer and eliminate the so-called “thermal runaway” event when a battery begins to generate more heat, continuing a chemical reaction that results in flames.

Batteries work by converting a chemical reaction into electrical energy. Electrons form a circuit by flowing from a positively-charged cathode to a negatively-charged anode through an electrolyte, which can be either liquid or solid. The voltage difference between the two electrodes produces an electrical current, which is then harnessed to run the device.

Researchers at the University of Texas developed the first lithium-ion rechargeable battery in the early 1980s, but it took another decade before it became a commercial success.

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