Did you know that laptop battery can explode? They do, and they have most famously on airplanes in recent years.
An onboard fire downed a cargo plane on February 8 at Philadelphia International Airport. Investigators found that some of the laptop batteries onboard had caught fire and exploded. Other lithium batteries were onboard and were unchanged.
This is a similar story to one told by another airline, which reported that a laptop battery stored in a bag in an overhead bin started smoking. This was on a passenger flight. Fortunately, the plane had not taken off yet; the battery was removed, and no one was hurt. The bag caught fire outside the plane, however.
The U.S. National Transportation Safety Board is conducting an inquiry into the matter. They uncovered similar stories from 1999, in Los Angeles, and from 2004, in Memphis. In both cases, lithium batteries caught fire on cargo planes.
Thankfully, this does not happen often. Thousands of travelers carry spare laptop and mobile phone batteries with them on planes everyday, and even more batteries are shipped around the world. Yet the threat is there, conceivably for any lithium battery that is damaged or encounters a short circuit.