Safer Lithium-Ion Batteries, Researchers Reveals Batteries with Built in Flame Retardant

Lithium-ion batteries have made headlines for the wrong reason: as a fire hazard. Just this past May, three apparent battery fires in Tesla cars were reported in the United States and Switzerland. In the United States alone, a fire in a lithium-ion battery grounds a flight every 10 days on average, according to the Federal Aviation Administration.

And the same problem afflicts electronic cigarettes, which have been blowing up in people’s faces sporadically.
No other drawback has so hobbled the advance of what is by far the most promising battery technology to emerge in our lifetimes. Lithium-ion batteries store much more energy than previous chemistries could manage, making them crucial to the future success of phones, drones, cars, even airplanes.

Solving this problem would not only protect lives and property, it would also make it possible to use larger battery packs with more closely packed cells. We’d finally be able to fully exploit the great energy-to-weight ratio, or specific energy, that this technology allows. What’s more, we’d be able to make progress with the next generation of batteries, the ones that use lithium metal.
In a lithium-ion battery, a thin piece of plastic separates the two electrodes.

"If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire," said Gabriel Veith from Oak Ridge National Laboratory, US Department of Energy's (DOE), and project's principal investigator. "
To make these batteries safer, some researchers use a nonflammable, solid electrolyte. But these solid-state batteries require significant retooling of the current production process.
As an alternative, Veith's team mixed an additive into the conventional electrolyte to create an impact-resistant electrolyte.
It solidifies when hit, preventing the electrodes from touching if the battery is damaged during a fall or crash.

If the electrodes don't touch each other, the battery doesn't catch fire.
Even better, incorporating the additive would require only minor adjustments to the conventional battery manufacturing process.
"If you put the mixture on a cookie tray, it flows like a liquid until you start poking it, and then it becomes a solid," said Veith. Once the pressure is removed, the substance liquefies again.
Veith now plans to enhance the system so the part of the battery that's damaged in a crash would remain solid, while the rest of the battery would go on working.

The team is initially aiming for applications such as drone batteries, but they would eventually like to enter the automotive market.
The team presented the results at the 256th National Meeting and Exposition of the American Chemical Society (ACS) in Boston on August 22.

August 24, 2018