U.S. officials grounded Boeing's new 787 Dreamliner because the aircraft's advanced batteries appear to be malfunctioning. But what's the problem? And can it be fixed?
To reduce weight on the plane, Boeing relied heavily on lithium ion batteries -- the same type found in mobile phones and laptops.
While these batteries can produce a lot of power for their weight, they're also prone to problems. It was these same batteries that caught fire in laptops a few years back and, more recently, were suspected culprits in electric car fires.
How they work: Lithium ion batteries use ions from the element lithium to tease out energy from the battery's electrodes, according to Donald Sadoway, a materials chemistry professor at the Massachusetts Institute of Technology.
This is different from other types of batteries commonly used in electronics, which use a combination of nickel and cadmium or lead and acid, among other things.
Why they're better: Lithium is the lightest of all metals, so its ions hold energy more efficiently -- more than twice as much per unit of weight as nickel cadmium batteries.
This made the batteries attractive for Boeing, which used them to electronically assist some of the functions that were previously performed using hydraulics. A lighter plane is more fuel efficient, which is one of the main selling points for the 787. Other aircraft makers have also been using more lithium ion batteries.
Related: Boeing's Dreamliner fleet grounded
In addition to being light and packing lots of power, lithium ion batteries also require less maintenance. There's no need to fully drain the battery before recharging, as was the case with older nickel cadmium batteries. Plus, they may be less environmentally toxic during disposal.
What's the problem? In addition to being the lightest metal, lithium can also be unstable when combined with other elements. Because of this instability, the batteries are subject to catch fire if they are over charged -- as was the case earlier this month with a 787 at a Boston airport.