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Big batteries are key to the planet’s future. But what’s up with these Bolt fires?
Aug 25, 2021

Big batteries are key to the planet’s future. But what’s up with these Bolt fires?

Despite the recent recall, lithium-ion batteries are still considered the best bet in the electric vehicle market.

The electric vehicle market got a little shake-up this month after General Motors recalled all of its Chevy Bolts due to the risk of battery fires.

The recall comes as the EV market is getting hot … uh, no. It’s set to explo — nope! There are going to be a lot more sales in the future.

I have some reservations. Literally. I have refundable deposits on two different electric trucks. Like many people, I’d like to know how a lithium-ion battery goes pear-shaped.

We asked Kristin Persson. She’s a professor of materials science and engineering at the University of California, Berkeley. She said damaged battery cells can get hot. The following is an edited transcript of our conversation.

Kristin Persson: So the heating of the cell then causes a series of events. First, the film that’s on the anode starts breaking down, and when that heat happens to the cathode, [it] start[s] releasing oxygen, typically. And then that oxygen burns the electrolyte, and that’s when things go bad.

Kristin Persson poses for her headshot in front of a red brick background wearing a grey and black top and smiling.
Kristin Persson (Courtesy UC Berkeley)

Jed Kim: So do we know specifically what the problem was in the Chevy Bolt?

Persson: Well, according to the GM announcement, it’s a combination of manufacturing defects, and those two defects were a torn tab on the anode side and a folded separator. These are real manufacturing defects. They’re not necessarily the materials themselves that are dangerous or worse than any other. It’s just literally something that went wrong during the manufacturing of the battery pack.

Kim: There have been some notable recalls beyond the Bolt, like Samsung Notes. I know that this lithium-ion battery is considered a mature industry, but are these incidences a reality check on that? 

Persson: If you look at the volume of batteries being produced today, and the price reduction that’s happened just in the last decade, we used to pay, like, $1,000 per kilowatt-hour for lithium-ion batteries. Today, I think, we’re below $100. And I would say that that’s a mature technology. I think what you’re seeing more in these sort of Samsung Notes, which were also manufacturing errors not so different from what we’re seeing in the Bolt, is more the fact that they’re trying to squeeze more and more energy into the same packaging. And by doing that, you’re getting down to very small margins in terms of safety, the size of the separator, things like that.

Kim: As electric vehicle sales are going to grow around the world, are you worried that more of these corners are going to get cut?

Persson: Well, hopefully not, right? I think every time something like this happens, it gets a lot of publicity, even though in the end battery fires in vehicles is actually still pretty rare compared to normal gasoline fires. But as you can see, GM is recalling every single one of their sold Bolts, which is a huge economic impact.

Kim: How much of our future is going to depend on lithium-ion batteries?

Persson: In my opinion, in the short term, that’s going to be still the most utilized energy-storage technology. It is a really hard technology to beat today because it’s commoditized, because we know, by and large, how to manufacture it and because it has a really high energy density. And for transportation, in particular, that’s important. For stationary, you could argue that reliability and cost could be more important. But in terms of transportation, lithium-ion is kind of the silicon of photovoltaics. It’s just the best we have today, and it’s reliable. We know its problems, and we can monitor them. Anyone who’s trying to compete with that will first have to scale up or be a lot better on day one, which is hard to see.

Kim: You said “short term.” What is short term?

Persson: Well, for sure, the next five to 10 years. The thing with energy storage is that it’s not like there’s going to be new technology that’s going to come overnight and take over the whole world. You’ll see it pop up in portable electronics, you’ll see it come in other kinds of markets before we see it in cars. So it’s gonna be a slow growth, so we’ll know the new technologies that are coming online.

Related links: More insight from Marketplace’s Jed Kim

Wired’s article about the crossroads between a Nevada lithium mine and a rare type of flower reads as so much more than your usual environmental David and Goliath story. That may be because it’s crafted as a murder mystery set on a mine worth billions. The murder victims, by the way, are a lot of wild buckwheat. It really gets at the angst of needing lithium to fight climate change and what it takes to get said lithium.

Norway is absolutely crushing it when it comes to adopting electric vehicles. Electrek has the latest sales numbers as of July, showing that 58% of new vehicle purchases this year have been electric! Old-fashioned internal combustion has accounted for just 10% of sales so far this year. How’d Norwegians switch over so fast? Their incentives are more stick than carrot. Rather than offer tax breaks for buying emissions-free vehicles like we do, they put heavy taxes on gas- and diesel-powered engines.

There’s a lot of research being done on new materials to put inside future lithium-ion batteries to make them more powerful and safer. In fact, Persson is looking into that. Well, researchers at Monash University in Australia have made some ground on using a new kind of salt that would help develop a more stable, less toxic battery. I share this story because it features a researcher with possibly the best name ever for someone who does this work. Her name is Mega Kar. And now, I hope it is also your dream that we will someday see the Mega Kar battery.

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The team

Molly Wood Host
Michael Lipkin Senior Producer
Stephanie Hughes Producer
Daniel Shin Daniel Shin
Jesus Alvarado Assistant Producer

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