What Are the Dangers of Lithium-Ion Batteries?

Last month, Samsung ordered an immediate recall of its Galaxy Note 7, S7, and S7 Edge lines of smartphones after a number of customers reported the phones overheating and catching fire while in use. These instances of exploding phones were due to faulty lithium ion batteries, and the incidents have not gone unnoticed. Airlines now warn passengers against taking these Samsung phones on planes, and the US federal government issued an official statement against buying the phones. Samsung’s problems aren’t unique to the company, however. They’re due to the nature of the lithium ion batteries that power practically all the world’s smartphones.

Lithium has a long history of causing the devices it powers to overheat. In fact, the same process that gives your cellphone its charge is the process that causes Samsung Galaxy Note 7s and “hoverboards” to catch on fire. The reason this happens is that lithium ion batteries contain a high amount of energy in a relatively small space. Lithium ion batteries have an energy density of 160 watt hours per kilogram (Wh/kg), which they produce with a positively charged cathode (made from a metal oxide), a negatively charged graphite anode, and a liquid electrolyte (which contains lithium salts) that enables the electrical flow between the nodes. If these nodes are closer than 10 microns in distance away from each other, things get heated, so a permeable polyethylene separator is used to keep the battery from overheating. Of course, when a battery is made more compact, there is far less margin for error.

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If the anode and cathode aren’t sufficiently far enough from each other, it short circuits and triggers a process known as thermal runaway — chemicals inside the battery begin heating up and the separator becomes compromised by the heat. By the time temperatures inside the battery reach about 1,000 degrees Fahrenheit, the electrolyte can ignite or, if exposed to oxygen in the air, literally explode.

Still, this doesn’t mean your phone is a ticking thermal bomb that should be disposed of immediately (unless it’s one of the Samsung models mentioned above). Despite these high profile instances of malfunction, lithium ion batteries are generally safe. Considering there are billions of laptops, cellphones, and computers powered with these batteries, incidents involving defective lithium ion batteries are relatively rare. Still, as our devices become more compact, so too do our batteries, which only compounds the issues of developing safer, less volatile systems for storing power. For now though, just be mindful when using your fire emoji when your phone’s charging.

For more battery solutions, check out PSafe’s PowerPRO battery-saving app — it reduces battery consumption, which means less risk of overheating your battery.