Follow Up


A look inside lithium-ion batteries and what makes them so dangerous

Posted at 9:15 PM, Mar 31, 2023
and last updated 2023-04-01 00:34:36-04

DACONO, Colo. — Crews at Mountain View Fire Rescue (MVFR), like so many departments across the country, are getting more familiar with a certain type of call — fires that involve lithium-ion batteries.

The batteries have caused devastating fires and create a risk for responding firefighters.

Denver7 reported on an Adams County fire investigator who had a battery explode in their face after a delayed reaction inside of it.

But what makes lithium batteries so dangerous? The answer is inside the battery.

Base of a cylindrical Lithium-ion cell

All of the layers are aluminum current collectors, rolled up into a cylinder to create the battery. One battery pack could contain several battery rolls.

When the aluminum and the white separator is unrolled, it looks like a long flat sheet.

Lithium-ion battery cell unwound, showing the white separator layer and the shiny aluminum current collector

"In order to pack more and more power, the foil and the insulator have to get thinner and thinner and thinner. When they get thinner, they get more delicate," said Deputy Chief Jeff Webb. "You can imagine if I damaged the little bit of insulation, the electrons will try to run from one piece of foil to the other without going through [the electronic being used]. That makes a little hot spot."

He explained the hot spot can get bigger and bigger as it spreads and burns through other layers, and eventually into other cells in the battery pack, causing a delayed cascading effect.

Lithium is also a water-reactive chemical, making the fire fight even more challenging.

"We have to worry about causing the fire to accelerate by using the water that we normally use to put the fire out. In cases that there is a significant amount of the lithium metal, we may use a different extinguisher, like a dry chemical extinguisher or something like that," said Webb.

Firefighters say it's important to only use chargers and batteries that are meant to be used together. Don't mix and match. Electronic users should also get rid of old or damaged batteries as soon as possible.

"If I used to be able to run my hedge clippers for 20 minutes, and now it's only 10. Or when I charge my battery up, it feels a little warm. Those batteries need to go. What it means is you're seeing the first indications of that battery degrading, and the insulation layer and the metals inside the battery are starting to show defects. When they show defects, they have a higher chance of catching fire," said Webb.

Do not throw batteries away in the trash. Firefighters say taking them to a specific battery recycling center is the only way to guarantee they will be disposed of safely.

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