ARI SHAPIRO, HOST:
Lots of Americans are considering buying an electric vehicle, or EV. One of them is engineer John Williams, who spoke with science reporter Ari Daniel outside of an EV charging station.
JOHN WILLIAMS: Inside each of these vehicles are hundreds, if not thousands, of lithium-ion cells, one of the densest ways that we know to store electrical energy in a battery. But they come with trade-offs.
SHAPIRO: One trade-off - every now and then they get too hot and even catch fire. But Ari Daniel tells us more about one material that Williams and the Department of Energy hope will help.
ARI DANIEL, BYLINE: This charging station's outside the R&D lab of Aspen Aerogels, some 35 miles west of Boston. Williams is VP of technical services. He says when a battery in an EV gets too hot, it can lead to something called thermal runaway.
WILLIAMS: The temperature goes up and up and up until eventually the battery catches on fire.
DANIEL: A lithium-ion battery is way less likely to ignite than an internal combustion engine, says Williams, but it burns hotter and is harder to put out - so not an ideal scenario for an EV.
WILLIAMS: So the goal for a vehicle designer is to give a passenger enough time to exit the vehicle, get off of the road.
(SOUNDBITE OF DOOR CLICKING)
WILLIAMS: Go looking for what is the world's best thermal insulation, and 30 seconds of Googling will tell you that that is an aerogel.
DANIEL: I sit down at a table with chief technology officer George Gould, who drops a piece of aerogel roughly the shape of a hockey puck on the table in front of me.
(SOUNDBITE OF AEROGEL HITTING TABLE)
GEORGE GOULD: This is a very ethereal material. It's very delicate.
(SOUNDBITE OF AEROGEL HITTING TABLE)
GOULD: They are a little bit translucent, you might say. There is a smoky appearance to the material. And I want you to get a feel for just how light it is.
DANIEL: It's like a really light, firm Jell-O.
GOULD: That piece is probably 99% air.
DANIEL: The rest is a super-porous material made mostly of silicon and oxygen.
IRENA MELNIKOVA: Can I start?
DANIEL: Yes, please.
MELNIKOVA: I put the timer.
DANIEL: Chemist Irene Melnikova shows me the process of making an aerogel. She takes two liquids - reprocessed silicone materials and an alcohol - combines them and then pours the mixture onto a patch of fibrous material that absorbs the liquid. Within a minute, it's solidified.
MELNIKOVA: It's amazing. Look. You have a fluid, and it's liquid, and after that you have a solid.
DANIEL: A solid with a rather useful property.
MELNIKOVA: It can survive at high temperature.
DANIEL: Next stop to see this high-temperature resilience - another lab. R&D engineer Matt Gwin shows me a piece of this aerogel material held taut inside a metal frame. This is what's placed between the lithium-ion cells of EV batteries currently inside certain vehicles made by GM, Toyota, Honda.
(SOUNDBITE OF PROPANE HISSING)
SHAPIRO: Gwin turns a couple knobs to get the propane flowing.
MATT GWIN: This is a lighter, so it's just going to be a standard, quick...
DANIEL: A jet of fire, some 2,000 degrees, erupts outwards towards the material.
You've got a flaming torch blowing at something that is just a couple millimeters thick.
GWIN: Yes.
DANIEL: And there's no flame coming out the other side. I mean, any other material you put in there would be completely incinerated.
GOULD: The secret of our material is that it's passing the energy on very slowly.
DANIEL: After a minute or two, George Gould says we can kill the flame.
GOULD: You're going to touch it right away.
GWIN: I was touching the hot face. You can touch it if you'd like.
DANIEL: Wow. That is amazing.
It's completely intact and just warm. You'd never know it had been scalded by a raging fire.
GOULD: It's like magic. Yeah.
DANIEL: An aerogel doesn't prevent a fire in the first place, but if a lithium-ion cell wrapped with this material ignites, Gould says the aerogel keeps the fire from spreading. Amar Pradhan is with Mobility Impact Partners, a venture capital firm that invests in emerging transportation technologies. He says aerogels are just one kind of intervention under development.
AMAR PRADHAN: There's different ways to stop the fire, depending on the timeline of battery fires. You can solve it before it happens. You can solve it while it happens. You can solve it after it's already on fire.
DANIEL: Pradhan says a range of approaches is necessary, especially given the lifecycle of a lithium-ion cell inside an EV and afterwards in a landfill.
PRADHAN: You could prevent the problem years before by picking a better chemistry. You could prevent it hours before by predicting it using data.
DANIEL: Still, the U.S. Department of Energy has taken notice of the materials that Aspen Aerogels is developing. They recently provided the company with a roughly $670 million loan to build a new factory in Georgia. For NPR News, I'm Ari Daniel. Transcript provided by NPR, Copyright NPR.
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