How safe are lithium-ion batteries?

You may have read a recent news story about a teenage girl whose Samsung Galaxy S 4 smart phone slipped under her pillow and began to smolder as she slept. She woke to find, as her father told TV station KDFW in Dallas, "The whole phone melted. The plastic, the glass. You can't even really tell that it was a phone."  

The Galaxy S 4 uses a lithium-ion battery, as do other smart phones and mobile devices as well as many other consumer products. Samsung pointed to a warning in its product guide, which states that covering one of its devices with bedding or other material could restrict airflow and cause a fire. The company also pointed out that this phone's battery was a replacement, not the original Samsung battery. (The company told KDFW it is investigating what actually caused this particular fire.)

So, are lithium-ion batteries inherently dangerous? And should you avoid using aftermarket batteries when your original manufacturer batteries wear out? We reached out to an expert to get some answers.

Jeffrey P. Chamberlain, Ph.D., the deputy director of development and demonstration for the Joint Center for Energy Storage Research at Argonne National Laboratory, explains why this incident likely happened: "If heat is not properly removed from either electronics or battery packs, the device can overheat, and cause a cascading reaction that causes plastic to melt and, in some cases, catch on fire."

Find out how Tesla dealt with a battery issue in the Model S.

But, Chamberlain adds, "There are literally billions of lithium-ion battery cells currently being used by consumers across the world. And, I've only ever heard of a handful of such incidents. So, such failures appear to be infrequent."

As to the question of replacing original batteries, he says: "Every phone and laptop computer I've ever bought comes with a user's guide; without exception, each one I've ever read warns the consumer not to buy replacement batteries or other parts, like chargers, from third parties. So, I assume from the fairly strict warnings that come with these products that, yes, it is unsafe to replace a mobile device's original battery with one made by a third-party manufacturer."

The bottom line: It's better to be safe than sorry. Follow your devices' manufacturer recommendations when it comes to used and replacement parts.  

—Carol Mangis