Blowing Up Batteries To Make Them Safer

This is what it looks like the moment a lithium-ion battery explodes after overheating. Fortunately, these catastrophic failures are exceedingly rare and result from an event called a thermal runaway.

This phenomenon happens when a battery undergoes mechanical or electrical trauma, or when it is exposed to an external heat source. In the worst-case scenario, this abuse starts the battery on the path of failure, when the reactions occurring inside start an energy-releasing breakdown and heat generation exceeds the battery’s ability to harmlessly dissipate it.

Because modern societies are becoming increasingly electricity hungry, rechargeable lithium-ion batteries are finding use in more and more applications, from automobiles to airplanes and personal electronics. That’s why researchers around the world are studying the basics of what goes on in the power sources and how to make them safer. Learn more and see a video below.

“As we move to more demanding applications, it’s crucial that we understand how these batteries can operate safely,” said Paul Shearing, a University College London chemical engineer who coauthored a paper published yesterday in the journal Nature Communications. “We’ve seen recently a number of high-profile incidents reported in the press associated with lithium-ion battery failure. Thankfully, these events are extremely rare.”



Now Shearing and his team in England and France have shown for the first time the moment of catastrophic battery failure. They used thermal imaging cameras to measure the details of thermal runaway and powerful 3-D X-ray imaging to peek inside at what the failure physically looks like while it is happening.

“What we’re trying to do here is understand using these experiments exactly how the failure begins and what the consequences of that failure are,” said Shearing. “Hopefully by understanding this mechanism of failure we can begin to mitigate against the likelihood of these failures occurring.”



The batteries they destroyed were subjected to temperatures that rose to almost 500 degrees Fahrenheit. At that point, the dramatic heat input triggered the exothermic breakdown of the battery’s contents and thermal runaway, during which the device’s temperature spiked above 1,800 degrees F. X-ray imaging offered the researchers significant new insights into the process of failure including gas-induced delamination, electrode layer collapse and the propagation of structural degradation. During the next stage of their work, the team will focus in on catastrophic failure at the microscopic level.

“We combined high energy synchrotron X-rays and thermal imaging to map changes to the internal structure and external temperature of two types of Li-ion batteries as we exposed them to extreme levels of heat,” said PhD student and study coauthor Donal Finegan. “By looking at these cells during failure we could potentially improve the safety of them.”

