'Almost like little bombs': Why do lithium-ion batteries explode?

CTV National News: Samsung Galaxy Note 7 recall Samsung is putting a pause on its latest smartphone due to a hazard causing the battery to explode and catch fire. Todd Battis reports.

With Samsung recalling 2.5 million brand spanking new Galaxy Note 7 smartphones after reports of them catching fire and exploding, you might be wondering, ‘Why can lithium-ion batteries burst?’

“Lithium-ion batteries are like little balls of chemicals that are almost like little bombs,” CTV technology analyst Carmi Levy told CTV News Channel.

“Properly designed, properly used, they’re absolutely fine and absolutely safe. But if they’re damaged, if they’re defective in manufacture, if the software that controls them is not proper, they can get very hot very quickly, and when they get too hot, they essentially either burn or explode.”

From smartphones to laptops, lithium-ion batteries fuel just about all of our rechargeable portable devices. They even power Tesla cars.

Over the years, however, they have been subject to massive recalls.

A decade ago, Dell recalled more than four million laptop batteries over reports of fires and explosions. Other companies, such as Sony and Nokia, have recalled millions more that were used in smartphones. Boeing was even forced to ground its fleet of 787 Dreamliner planes in 2013 after lithium-ion batteries overheated during flights.

In scientific terms, the problem is called “thermal runaway” -- a situation in which high temperatures create a chain reaction or domino effect that causes temperatures to continue rising, leading to combustion in the most extreme cases.

While companies have created failsafes, such as software that stops a phone from charging once its battery is full, the problem persists to this day, even though the batteries have been commercial available since the early 1990s.

In the meantime, Levy recommends always charging your smartphone on a hard surface instead of something soft, like a pillow or blanket. You should also unplug your device as soon as it’s fully charged.

“It’s a fundamental issue with lithium-ion,” Levy says of overheating. “The industry has needed to deal with it for years. They need to deal with it now.”