Zero-tailpipe emissions transportation like electric cars may be key to cutting carbon – but manufacturing them has a not-so-green downside: lithium Ion batteries.They’re the dominant technology when it comes to just about anything rechargeable, from cars to cell phones. But mining materials for the batteries is wreaking havoc on the environment, essentially trading out one ecological problem for another.
Now, a new breakthrough from researchers at the University of Texas brings gets closer to a more sustainable alternative to lithium batteries by using sodium.
Sodium-based batteries aren’t an entirely new concept, but creating stable versions has been a challenge. Earlier versions would sometimes catch fire or explode. They also didn’t hold their charge as well as lithium ion batteries.
“Basically we’ve developed kind of an inexpensive metallurgical way to make sodium metal anodes that are extremely stable during cycling,” said Professor David Mitlin with UT’s Cockrell School of Engineering.
Listen to the interview above or read the transcript below.
This transcript has been edited lightly for clarity:
Texas Standard: Sodium batteries are not an entirely new concept, right?
David Mitlin: No, There’s commercial embodiments of them. It’s a very active area of research. Department of Energy is doing a lot of work on that. They’ve been out there for a while. They don’t quite compete with lithium as far as performance, but then they make up for it in some applications in terms of costs and environmental benignness and the fact that you can find sodium almost everywhere.
Texas Standard: I guess one of the big challenges, if you’re trying to do a face-off against lithium batteries, they don’t hold the charge as well, or they’re just not quite as efficient as lithium?
Sodium is just a much bigger ion. So it doesn’t move as well through the battery. So sodium batteries typically don’t hold as much charge, and they don’t have as high power, which for some applications really matters, but others matters less.
Tell us more about your research. Have you achieved a kind of a breakthrough here?
I think we’ve achieved a breakthrough. I’ve been working on sodium batteries since 2012. I’m probably one of the earlier people to get in the field. And this thing is a pretty neat idea. Basically, we’ve developed an inexpensive metallurgical way to make sodium metal anodes that are extremely stable during cycling. So in principle, you could do it cheaply and get much better safety out of it than you could out of other flavors of this kind of an anode.
And I guess that’s been one of the concerns about lithium ion batteries is that sometimes they aren’t that stable, right?
Actually, what we’re looking at are sodium metal batteries and lithium metal batteries. So they’re kind of like the next generation. They hold about 50% higher energy than commercial batteries, but they have a whole bunch of safety problems and manufacturability problems. And I think for sodium metal batteries, what we did probably moves the needle as far as both manufacturing cost and making it safe, avoiding any kind of a fire or catastrophic event.
Let’s talk a little bit about the environmental impacts. What’s so bad about lithium mining as you understand it? And was that something you were trying to address in your research?
First of all. I’m not a mining expert. But I think the things that people are concerned with about lithium are actually not the lithium, but the cobalt and the nickel. Those are the elements that are hard to come by in the lithium ion battery cathodes. Geographically, cobalt mostly comes from the Democratic Republic of Congo anoda few other places. It’s hard to come by and there are geopolitical issues.
With sodium, you can make a battery with iron and copper cathodes and really have a much easier domestic sourcing of, effectively, all your materials. So sodium can come from seawater. There’s also a lot of sodium carbonate out there, a lot of sodium hydroxide. The cathode could be iron and copper. So the whole battery becomes much more democratically obtained.
So how long before we start to see the sodium batteries of the type that you’ve been working with in the mainstream? I mean, available in the marketplace, perhaps as a substitute for applications where we’re seeing lithium ion batteries today
For nonautomotive applications, it’s a real viable option. There is some commercial stuff out there already. In reality, I think as lithium takes over the world, there will be more and more demand for alternative kinds of lower-cost energy storage technologies that are green as well.