Sodium Replaces Lithium In A New Type Of Battery

IRA FLATOW: This is Science Friday. I’m Ira Flatow. To meet green energy goals, experts argue that a crucial component will be a worldwide shift to batteries. For that to happen, we’re going to need a lot more of them. And the current most popular kind of battery, you know, the lithium ion, is not a great candidate for this kind of scale up due to its reliance on scarce resources, controversial mining practices, and polluting production processes.

But solid-state batteries could offer some solutions here. That technology is still in development, but new research from teams at the University of Chicago and UC San Diego details a first of its kind solid-state battery architecture that trades out the rare and problematic lithium for the much more abundant sodium. You know, the kind of stuff that’s in salt.

Their results were published in Nature Energy. And here to tell us more about the advancement is my guest, Dr. Shirley Meng, Professor of Molecular Engineering at UChicago and Chief Scientist for Energy Storage Science at Argonne National Laboratory. And she was an author on that paper. Dr. Meng, welcome to Science Friday.

SHIRLEY MENG: Hi, Ira. Glad to be here.

IRA FLATOW: Nice to have you. Let’s talk a bit first about why we need more batteries for a greener power grid.

SHIRLEY MENG: Well, as we transition to renewable sources like wind and solar, we all know that wind does not blow all the time, and we only get about eight hours sunshine. So I think it’s very important for us to have the energy storage mechanism to deal with the intermittency of these renewable energy sources. That’s why battery is very, very critical for this energy transition.

IRA FLATOW: You know, a lot of people haven’t heard, I don’t think, about solid-state batteries. We’ve talked about it briefly on the show. But please, give us a refresher on why they’re such an appealing candidate for electric cars and this greener power grid.

SHIRLEY MENG: Certainly. Solid-state batteries is referring to replacing one of the important components in the battery, the flammable liquid, to solid materials. This will enable us to build the batteries with very high energy density while not sacrificing the safety aspect.

We are all very excited with this possibility because it’s possible that we will now build an electric vehicle that, per charge, will lead to 500 miles. And it’s possible that we can actually put the batteries in our house, just like a refrigerator for electrons. That provided us a lot of flexibility in terms of how we design the grid of the future.

IRA FLATOW: You said something very important. You talked about the solid-state battery having the same energy density of lithium batteries. That energy density concept is important, is it not? And how then do you build that into these new solid-state batteries.

SHIRLEY MENG: Yeah. So energy density refers to how much energy we can pack in certain weight or how much energy we can pack in a fixed volume. So for instance, the way how current cars, electric vehicles are designed, from outside, you cannot really tell the difference if it’s run on internal combustion engine or it’s run on electric motor and batteries.

So the design constraint is in that fixed volume, we have to put enough batteries that will keep the cars run the long distance. So I would say the energy density concept is a design constraint that all the battery people have to work within. And this is the reason why lithium ion batteries made such a positive impact in the electric vehicle, because you can’t really use your AA batteries or your lead-acid batteries for that purpose because of their low energy density.

IRA FLATOW: And your research actually helped overcome a problem that allows you to use these new batteries?

SHIRLEY MENG: That’s right. Yeah. As you mentioned in the beginning of the show, that lithium and what we use in the lithium ion batteries that contains nickel, cobalt, copper, those elements are scarce, and they take a lot of energy to mine them. So the work we are doing is trying to get rid of those critical elements, build the batteries based on abundant materials, for example, sodium, and then we actually can eliminate the copper, and then just use aluminum as the current collector.

And we can actually build AA batteries made with sodium ion, manganese, oxygen. So all those elements are what we called the rock forming elements, and they are very abundant on the planet Earth.

IRA FLATOW: And some hardware and electric car companies have started to use these solid-state batteries. Is that right?

SHIRLEY MENG: In the prototyping stage, yes.

IRA FLATOW: Yes.

SHIRLEY MENG: I think, for mass production, we still have certain hurdles to overcome.

IRA FLATOW: So let’s talk about the hurdles that need to be overcome and why you think that they can be overcome.

SHIRLEY MENG: The way how current lithium ion batteries are being scaled up is they’re done in the factory called gigawatt factories. And those process right now utilize very large areas to produce the lithium ion batteries. And we are hoping that the process of making batteries could be further simplified and the efficiency could be improved.

So in solid-state battery manufacturing, the hurdles are, at the moment, it is still a nascent technology. So the giga factories are built for lithium ion batteries. So you can’t really do a drop-in solution to make those solid-state batteries, that they require a reinvention of how the factory should look like.

So I think this hurdle is rather challenging. And as many investments have already been made to scale the gigawatt factories worldwide, I think that the pioneers in this area for solid-state batteries really have to think about how we can do this with very strict timeline. And we actually have to showcase solid-state batteries indeed can outperform lithium ion batteries. I think that the scaling challenge is rather difficult.

IRA FLATOW: Your research talks about you’re making a big discovery, which is the development of anode-free architecture for sodium-based solid-state batteries. What is that, and why is that so important?

SHIRLEY MENG: Sure. Let me just step back to talk about how the architecture of a lithium ion battery is. So in any batteries, you need a negative electrode, anode, and you need a positive electrode, cathode, and then you have the electrolyte. These three components are really critical.

So in our architecture design, we figured out a way that during the manufacturing process, we can eliminate the need to fabricate the negative electrode, which is called anode. So we could imagine that the simplification of the manufacturing process could lead to multiple benefits. One of them is, of course, you simplify the manufacturing step, and the other one is that you can reduce the cost because we are not implementing the negative electrode during the manufacturing process, but the anode will be formed during the first operation of the batteries.

I think that’s a novel concept that comes out from our research. Particularly, we are actually doing it with the chemistry that’s based on sodium, some kind of element that everyone knows, that’s very abundant. It’s vastly available. So.

IRA FLATOW: Is that instead of lithium?

SHIRLEY MENG: Exactly. Instead of lithium. In our battery, we don’t need to use lithium. And sodium, actually, if you recall the periodic table, on the first column of the periodic table, sodium is right below lithium. A little bit heavier. But counterintuitively, people don’t realize that sodium can move very fast.

Sodium ions can move very fast in both liquid and solid. So actually, the sodium solid-state batteries can also offer fast charging capabilities and very high power rate. So we don’t have to sacrifice much of the performance when we replace lithium with sodium.

IRA FLATOW: Why didn’t we do that just at the beginning if it’s so much easier?

SHIRLEY MENG: Yeah, there’s an interesting story here that, in fact, sodium is not beyond lithium. We are behind the lithium. In fact, the initial research was initiated by a group of French scientists back in 1960s during the first oil embargo crisis. However, I would say the scientists who work on the lithium chemistry made their breakthroughs in enabling so-called intercalation chemistry.

I know it’s a jargon, but basically, they found that graphite and the lithium cobalt oxide, these two materials can reversibly insert and de-insert lithium for thousands of cycles. So I think that one of the main reasons is that the lithium outperformed the sodium back in the ’70s and sodium was really behind.

IRA FLATOW: So we’re taking a Back to the Future sort of thing.

SHIRLEY MENG: I love that verse. Yeah, exactly. Back to the future.

IRA FLATOW: Yeah. So is there a certain kind of application for sodium solid-state batteries that they would really thrive in?

SHIRLEY MENG: I certainly hope so, even though I think our research is at relatively low technology readiness level. We call it the TRL level 2 or 3. So we demonstrated the concept that sodium solid-state batteries with anode-free architecture could work. But we project that the sodium solid-state batteries can do as well as some of the lithium batteries.

So you can imagine that if electrification for mobility is everywhere, I think in countries like India, China, actually in major metropolitan cities like Paris, Chicago, LA, we could actually use sodium batteries that provide driving ranges comparable to that offered by lithium. So yeah, I think the supply chain security being offered by sodium is very exciting.

I think as a scientist, we typically don’t think about the geopolitics, but in the field of energy transition, we don’t have a choice. I think we do have to worry about the supply chain security. And I think the ability for us to make sodium-based batteries, diversify the choices for batteries, it’s always a good thing when we have more diversified choices.

IRA FLATOW: Well, that’s an interesting point, because I know you’re chief scientist for energy storage at the famous Argonne National laboratory, a federal laboratory. How much of your work, then, on moving forward with sodium batteries and batteries in general, depends on government incentives to keep this going?

SHIRLEY MENG: I think it’s an important role that government incentive will play because the energy crisis and the climate change that we are facing, I think that in order to meet the time constraint, that we probably have two decades to fix our grid of the future, I think that the government incentive will play a critical role in terms of how we could scale things fast and how we can actually make sure that localization, the domestic manufacturing of important energy storage technologies could happen.

So Argonne actually, back in 1992, is one of the first places in the United States that started research on energy storage, particularly lithium ion batteries. I think we continue to focus on how we can actually provide the best efficient energy technologies for the US, and the current focus is really trying to offer a very secure supply chain so that the domestic manufacturing of those important technologies could be accomplished.

IRA FLATOW: Yeah. I understand the teams have filed a patent through UC San Diego for this discoveries. And whenever we get a new discovery, especially in energy, and you’ll ask, When are we going to see this?, it’s always, well, it’s just five years down the road, or it’s 30 years away if it’s fusion. It’s always that far in the distance. How long do you think it really will be before solid-state battery tech is at a place where it could be manufactured on a long– on a large scale?

SHIRLEY MENG: Yep. I think this crystal ball I have back in my office is really working quite well. So let me just say a few things about the future of solid-state batteries. I think a lot of people didn’t realize that polymer-based solid-state battery is already a commercial product. In fact, some people are riding those buses in Paris right now during the Olympics.

IRA FLATOW: Really?

SHIRLEY MENG: Yep. The lithium version of the solid-state batteries, I think the ones that are based on so-called ceramic-based solid-state electrolytes, many tier 1 manufacturing battery companies are working on it right now. Toyota has made a public announcement, followed by Samsung. And I believe the latest one probably is Nissan.

I think that we will see some very interesting solid-state battery design commercial products, probably 2027 or 2028. For the technology we are working on for sodium, I think that if the manufacturing processes, we could leverage on what’s already been developed by the companies who are working on lithium solid-state, sodium solid-state can happen in the next five years, five to seven years.

I do want to emphasize that a lot of it will really depend on the determination of the entire society, that we are indeed going for electrification of everything. I think there are a lot of doubts and the speculations that maybe we won’t be able to do it. I hope that the sodium battery concept show people that lithium is not the only option, that we can make sodium batteries work.

And perhaps in the future, some people will make aluminum batteries, magnesium batteries work. So I think the technology advancement for all these new battery chemistries are extremely exciting. So I want to tell you that in the next three to five years, we could expect some very, very exciting new solid-state battery technologies coming online.

IRA FLATOW: Well, I can’t wait, Dr. Meng. Thank you for enlightening us on that, and we’ll keep an eye out.

SHIRLEY MENG: Pleasure to chat with you, Ira.

IRA FLATOW: Dr. Shirley Meng, Professor of Molecular Engineering at University of Chicago, Chief Scientist for Energy Storage Science at famous Argonne National Laboratory.

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