Volts podcast: battery analyst Chloe Holzinger on the possible futures for lithium-ion

Welcome back, my Volts friends, to the Battery Week that never ends. (Just kidding — this is the last of it.)

For several weeks now, I have had my head buried in batteries, specifically, lithium-ion batteries: how they work, why they have taken over so fast, what different varieties are competing for which markets, and where innovation will take them in the future.

Even with as many PDFs as I’ve read, I'm still learning every day just how much I don't know. I'm not going to lie: I still have the Wikipedia page for lithium-ion batteries open in a tab.

So I thought it would be nice to round out battery week with someone who actually knows what they're talking about. To that end, I was happy to chat with Chloe Holzinger, a battery analyst at IHS Markit. (At least, that’s what she was when I spoke with her, and how I introduce her on the pod; since then, she’s become an Investment Associate with The Engine, a venture capital firm spun out of MIT.)

Chloe keeps up with lithium ion batteries for a living, so I was eager to talk with her about the growing market, the raw materials that make up batteries and their possible supply problems, the coolest new innovations in batteries, from solid state to liquid metal, and much more. She was generous with her time and I learned a ton. Enjoy.

David Roberts   

Hello, everyone, this is Volts and I am your host, David Roberts. For several weeks now, I have had my head buried in batteries, specifically, lithium ion batteries: how they work, why they have taken over so fast, what different varieties are competing for which markets, and where innovation will take them in the future. Even with as many PDFs as I have under my belt now, I'm still learning every day just how much I don't know. I'm not going to lie, listeners, I still have the Wikipedia page for lithium ion batteries open in a tab. 

So I thought it would be nice to round out battery week with someone who actually does know what they're talking about. To that end, I am joined today by Chloe Holzinger, a battery analyst with the clean energy technology and renewables team at IHS Market, a research and analysis firm. Chloe keeps up with lithium ion batteries for a living. So I was eager to talk with her about the growing market, the raw materials that make up batteries and their possible supply problems, the coolest new innovations in batteries, from solid state to liquid metal and much more. She was generous with our time and I learned a ton. So without further ado, let's get to the conversation.

Welcome, Chloe. Thanks for coming on Volts.

Chloe Holzinger

Thanks, David. Thanks for having me.

David Roberts   

All right, let's start maybe just a little bit by telling us how you ended up in the battery area studying batteries, analyzing batteries in the battery market. It's a strange niche field; how'd you end up there?

Chloe Holzinger  

Yeah, I sort of fell into it by accident, as so many people do. I got my undergraduate degree in Marine Chemistry and my master's degree in Mechanical Engineering, and happened to find the one startup in the Boston area that was developing batteries for underwater applications. So I joined them as employee number six, got a patent, and worked for them until they got acquired by a defense contractor. I then hopped over to the market intelligence field, where I've been covering the broader next generation battery technology area, and the various end applications for batteries. And I've been here ever since.

David Roberts   

How long has that been? How long have you been immersed in batteries? 

Chloe Holzinger  

Total, including the startup experience, is probably about five years.

David Roberts   

It's been an active time in that field! Let's just briefly talk about what lithium ion batteries are and where they came from. I think everybody's heard of them. At this point, they've kind of gotten a lot of hype, but maybe tell us when they entered the market, their market development and why they're kind of reaching this crescendo of hype right now. 

Chloe Holzinger  

Sure. So I can provide a very brief history here. Lithium ion batteries were kind of invented separately at different stages by different companies. If I remember correctly, Kodak did some innovation on actual tape casting, which is the process that's used to actually make lithium ion batteries. Some of the core lithium ion battery technology itself was actually developed at Exxon way back when; they just kind of sat on that. Then some other different key breakthroughs were also developed at different corporations; I think Sony was one of them as well. I may apologize if I got any of that wrong. But they really were initially commercialized for the consumer electronics industry. 

Then smartphones and computing power got much better, laptops became more commonplace, they were able to eventually make the jump from consumer electronics and these small applications, to electric vehicles, whether you're talking about a Tesla or Toyota hybrid, lithium ion batteries have been pretty crucial. And now we're seeing them used in all these different kinds of electric mobility applications, as well as the grid storage space.

David Roberts   

What was the first time they showed up in an electric vehicle? Because, just intuitively, the leap from a laptop to electric vehicle seems like a pretty far leap. Who had that idea and made that happen the first time? 

Chloe Holzinger  

You know, I don't actually know the exact history, but various people have been trying to make electric vehicles for a really long time. It's just before they were trying with lead acid batteries. So there were a few electric vehicle prototypes in Jimmy Carter's time, and they obviously didn't really go anywhere. As much as people have lots of lots of opinions – and I certainly do as well – about Elon Musk, you got to credit Tesla for really making the electric vehicle really sexy and popular again. 

David Roberts   

Is it fair to say that Tesla, back in the Roadster era, which I guess was like 2008 or 2009, that that's kind of what kicked off the current frenzy of development? Or do you think it was inevitable?

Chloe Holzinger  

I think both. I think Tesla was really there. Right place, right time, right idea, which is a pretty tough combination to come up with. I think regardless, you're seeing electric vehicles really rise in all different parts of the world and different companies really leading the charge. And it's such an integral part of decarbonizing transportation and industry. You know, if it wasn't for Tesla, I'm sure it would have been some other company. But it happens to be this particular American company that really got it started here in the States at least.

David Roberts   

So, what's so great about lithium ion batteries? Let's just, just briefly kind of look at the chemistry in the materials. We had lead acid batteries, we had nickel metal hydride, nickel cadmium batteries; batteries have been around. So, at the sort of the chemistry level, what is it about lithium ion batteries, that's so great, that has allowed them to colonize these markets?

Chloe Holzinger  

I could wax poetic about lithium ion batteries. A lot of what I do in my various market roles is talk about all these other non lithium chemistries that people are trying to develop. And there really isn't a better alternative to lithium ion batteries for electric vehicles. Lithium ion batteries are exactly the right combination of energy density, it has good enough cycle life, which means that it has a fairly good battery life, it has great power density, it's able to charge in a reasonable amount of time, you know, all of these different factors. There are certainly some safety issues, but they're pretty safe. All of the other different kinds of battery chemistries out there, they have various strengths and weaknesses, but they're really unable to compete on all of those fronts for a vehicle application. 

You have these various different grid alternatives like flow batteries, some of which use vanadium or zinc. Those are really big and heavy; they are not light enough, simply, for a vehicle application. Lead acid batteries –  you replace your lead acid battery every few years or so in your car. It doesn't have a great cycle life; it certainly doesn't have a strong enough energy density in order to fully electrify a car with a reasonable all electric range. There's really just no competition with lithium ion batteries for mobility applications.

David Roberts  

Does that have something to do with lithium itself, just as a material? I mean, is lithium itself the secret sauce?

Chloe Holzinger  

In some ways, yeah. If you'd whip out your handy dandy periodic table that I know everybody carries around with them, lithium is towards the top [left] of the periodic table, which means that it's one of the lightest elements.

David Roberts   

So it's top left, I'm checking here. It looks like it's the [third] lightest material. 

Chloe Holzinger  

It is, and right below lithium should be sodium. I haven't completely disappointed my chemistry teachers. Even if you go to that one row below lithium, that's a much bigger atom, and that bigger atom means that the energy density of that battery system is going to be smaller: you're going to have less ion exchange per kilogram of material. So the lightness of the lithium atom or element or ion is definitely a part of what makes lithium ion batteries superior to so many other different battery technologies. 

There are a few other different arguments here–there are some batteries that are multi-valence, in that they exchange a couple electrons instead of one electron, but those are still extremely early on in their development.

David Roberts   

Well, let's talk about the lithium ion battery market then. So you said, they sort of grew and completely ate consumer electronics, and then have jumped up and basically now dominate  EV's, I think. So what's the sort of lay of the land on lithium ion – where they're being used, what's driving all of this development and innovation?

Chloe Holzinger  

It's really the electric mobility space. Lithium ion batteries today are definitely good enough for an all electric vehicle, as we're clearly seeing. There are a few different factors that are driving further innovation in this area. So first is that automakers really want to be able to rely on this lithium ion battery value chain for the long term. There are a variety of different questions; whether or not they're valid is another point, but there are a lot of doubts about whether or not various key metals are able to scale up their production to meet some of these astronomical projections that automakers have around electric vehicles. Some of the crucial ones are nickel, cobalt, and lithium. There's a lot of innovation right now around developing technologies that are more robust against some of those fluctuations in key metals’ supply, demand, and pricing.

David Roberts   

I know they're expected to grow; every chart you see has the line shooting up into the right. But in terms of scale, compared to current nickel or cobalt demand for batteries, are we looking down the road at 2x, 10x, or 100x? When people are daunted about the scale of these metals, what do we mean by scale exactly? What are these projections?

Chloe Holzinger  

I think right now, for scale, all electric vehicles are 2 to 3% of annual new car sales. Automakers are saying that they're going to go all electric by 2035 or something, and California wants to ban ICE [internal combustion engine] vehicles by 2050.

David Roberts   

Washington actually just said no new ICE vehicles sold after 2030.

Chloe Holzinger 

Yeah, I mean, that's even more aggressive. And so to even meet that kind of target, you're talking some pretty dramatic scale ups of these upstream industries. In the lithium industry, lithium ion batteries were something about 30% of the total lithium market before electric vehicles took off, when it was really just consumer electronics. Today, 65%-67% of all lithium products go into lithium ion batteries, with the remainder being like glass and pharmaceuticals and all of these other kinds of niche applications. The lithium industry is really being driven by the lithium ion battery market. The nickel and cobalt industries are a bit different. But that's just [?????]

David Roberts   

Is this driving prices up? I mean, with all this new demand for lithium, has price become a problem yet, just for the raw material?

Chloe Holzinger  

No, not for any of the raw materials really. But right now, cobalt is really both the most expensive battery raw material, and the most well known to be sustainably problematic, whether you're talking about the human rights issues or the mines themselves. There's been a lot of coverage on the issues with cobalt mining.

So there's been this effort over the past several years to move away from cobalt, because of these primarily price and sustainability reasons, but also because there are simply better technologies out there than some of these high cobalt chemistries. There are a ton of different battery chemistries and a ton of different lithium ion battery chemistries. And there are strong advantages to battery chemistries that don't use cobalt on the energy density front, on the cycle life front for some chemistries; there's just a wide diversity of chemistries out there that really make it possible for automakers to pick and choose what types of lithium ion batteries they really want to use for which models.

David Roberts   

Let's get into some of those variations and I'm curious about the sort of variations in chemistry and also sort of like what performance sort of advantages and disadvantages come with us with these different chemistries. 

So, the two sort of dominant chemistries, right now, or what have been for a while are NMC and NCA. NMC has nickel, manganese, and cobalt with its lithium, and NCA has got cobalt and aluminum. Both those notably involve cobalt. I know there's been some effort just within those categories to sort of change the proportions and shrink cobalt. Who's doing that, and what does that involve? What do you lose by losing cobalt, and what do you need to compensate?

Chloe Holzinger  

Pretty much everybody's working to reduce the amount of cobalt in these batteries. The NCA technology is really almost exclusive to Panasonic and Tesla, and they're currently really the only NCA mass producers. So NCA batteries are therefore used predominantly by Tesla for its electric vehicles, and they're not used at all in grid energy storage systems.

David Roberts   

And that's because they're extremely high energy density right? Is it something to do with the aluminum?

Chloe Holzinger  

Yes, they are very high energy density, and the Tesla Giga factories have been struggling to keep up with Tesla demand for a few years now. So even if there was demand for NCA batteries and energy storage systems, there just isn't supply for that. For Tesla in the NCA chemistry, they've been able to reduce the amount of cobalt in their batteries from 20% to 10% now. So they've been able to significantly reduce the amount of cobalt in those systems. 

For NMC, you know, this is the most commonly used cathode formulation in lithium ion batteries today. And as you noted, there are many, many different NMC formulations with varying ratios of those key nickel, manganese and cobalt components. This is where, to your question, it gets very interesting, in terms of varying the amount of cobalt. The early versions of NMC had equal amounts of nickel to manganese, cobalt, or NMC111. And the technology has since progressed to now, where there's a lot of talk and support for high nickel cathodes, which would be eight parts nickel to one part manganese to one part cobalt. So that's, again, if you're thinking about the ratios, dramatically reducing the amount of cobalt there, and the benefit is that these high nickel cathodes enable much greater energy densities. But the converse, the trade off here, as you noted, is that these high nickel cathodes are a bit less thermally stable than the lower cobalt cathodes, and that can impact cycle life and safety. So some of the reason why it's been a bit more difficult to commercialize these high nickel cathodes for mass produced electric vehicles, outside of China, is that some of these batteries need extra safety features at the pack level in order to counteract some of that increased thermal instability.

David Roberts   

Right. And when you add cooling systems and whatnot, you add weight and thus, lose a little bit of your energy density advantage.

Chloe Holzinger

Right, exactly. 

David Roberts

But the NMC 811 chemistry, that's the thing now, right? It was a GM that just sort of debuted that fairly recently. I thought it's all it's all the rage. 

Chloe Holzinger  

Yeah, it's definitely a thing. It's been used in various electric vehicles in China for a year or two now, maybe a bit longer. And as you noted, it's definitely made its way outside of China as well. Even Volkswagen says that they are planning on using high nickel cathodes in their luxury vehicles. 

But, at the same time, you've also seen the rise of this other chemistry called LFP which is lithium iron phosphate, which has the lowest energy density compared to NMC and NCA, but it doesn't have cobalt and its core feedstocks, Iron and phosphate, are much easier to procure and much less vulnerable to price spikes than nickel, manganese or cobalt.

David Roberts

Right. And the loss of energy density for these LFP batteries–is that mainly because of the loss of nickel, just because iron and phosphate just won't hold as many ions as nickel? Is it that simple?

Chloe Holzinger  

It's a little bit more complex than that. It has to do partially with the cathode crystal formulations and really the cathode structure, which I really don't think I could explain at an intelligent level. You know, suffice it to say that LFP is structured entirely differently from NMC and NCA, and that different structure isn't able to hold as many lithium ions in a small enough space as NMC and NCA. And, iron’s heavy. These are not necessarily light batteries. 

But there have been innovations in pack design. With LFP, one of its advantages is that it does have better cycle life and it does have higher safety performance than NMC and NCA. We saw last June that BYD released a new battery pack architecture that removed a bunch of the safety features that were in there for NMC and NCA, and this pack architecture is specifically for LFP batteries in electric vehicles. At the pack level, these LFP batteries do achieve very competitive energy densities such that Tesla can use an LFP battery pack in its vehicles in China, and have those vehicles really achieve very competitive ranges and energy densities, compared to its NCA batteries back here.

David Roberts   

Right. I think in the Tesla battery day presentation, I believe the way they put it was that LFP–just the chemistry–has 50% of the energy density of their high nickel chemistry. But at the pack level, you get 75% of the range, because of the lack of safety and cooling, and everything. VW actually said something similar with that–they're going to use LFP in their lower end, sort of workaday cars where you don't need energy density. 

Let's just pause here and talk about energy density for a minute. Energy density – tell us what energy density is, and why it's so prized in these applications.

Chloe Holzinger  

Yeah, so energy density is basically, very simply, the amount of energy you can cram into a particular kilogram or volume of space. So there's gravimetric energy density and volumetric energy density. You want more energy in that set unit, because then that extends the vehicle’s range, if you're talking about a vehicle application. So higher energy density batteries are able to go further, drive further between charges. And range anxiety is really one of the key things that particularly Americans cite as one of the reasons why they're not interested in buying an electric vehicle. They're concerned about not being able to easily drive to visit family or friends, or their annual trip to their favorite vacation spots, or go skiing. You know, there are so many different things to do in this country, and some of them are pretty far away. EV charging station networks are continuing to be built out, but people are still citing range anxiety as one of the key inhibitors for them to actually commit to an electric vehicle.

David Roberts 

Right. So when we talk about energy density, we're mostly talking about range. We're just talking about how much energy you can cram into the battery in the same space. 

I had this in a separate section, but we're into it now. Let's distinguish that quickly from power density, which is a slightly different thing. Can you tell us what power density is?

Chloe Holzinger  

Yes. Energy and power are like two sides of the same coin. So, energy is basically the total amount of, let's say, electrons in a given volume in a battery, for example. So your battery pack will have a very specific energy capacity. Power is the rate at which those electrons leave that battery to go do other things. So power density really refers to how quickly can you get that energy out of the battery, how fast those electrons leave.

David Roberts   

Oomph Is the word I use. 

Chloe Holzinger  

Yes, exactly. With lithium ion batteries, they do have their own particular variations in power density. But a lot of that ends up being irrelevant when you put it into a pack. You're seeing a lot of different pack architectures; there's some high voltage pack architectures that are more efficient now. And so, the power density isn't really something that folks are optimizing for at the moment.

David Roberts   

Isn't that, though, what gives you your zero to 60 in two seconds, or whatever it is they're saying now? 

Chloe Holzinger  

That really doesn't really have to do with the battery chemistry so much. Just like you can fast charge your car, you can definitely discharge your battery pretty quickly if you want to. It's just whether or not that harms your battery system. So there has been some research on better enabling fast charging for electric vehicles.

David Roberts   

Right. So fast charging, it's just for the flip side of power density, right? It's like how quickly you can release the energy and how quickly you can accept it. Is that sort of together? Those are kind of the same thing?

Chloe Holzinger  

Yeah, yeah. The flip side is that if you discharge your batteries super quickly, you can, A) harm the lifetime of your battery, and B) then that impacts your range, because there's fewer electrons in your battery then. So that's why your hybrid, or I guess my little Honda Insight, has an Eco Mode, where it controls how fast you can accelerate and things like that.

David Roberts   

Oh, interesting. And how is that Eco? Is it just Eco because it makes the battery last longer?

Chloe Holzinger  

Sure, I’m pretty sure that's the only thing it does. It does seem to impact my air conditioning, too. But I'm not entirely sure what good Eco Mode does, except I get five stars if I do well.

David Roberts   

So, obviously, energy density is dominating in the EV space, since most of what people want out of an EV these days is greater range, and that's kind of what people are pushing toward. So I'm sort of curious, EVs are by far the biggest market for these batteries, so my sort of assumption is that whatever the EV market wants, that's what's going to drive innovation. And sort of whatever the EV market ends up choosing is just going to scale up so big and get so cheap that it's going to be cheaper for other applications too. 

So I guess what I'm asking is, outside the EV space, what are the other applications for lithium ion batteries, maybe where energy density is not the prime consideration? Are there other factors that developers and researchers will be chasing, sort of other performance characteristics other than energy density?

Chloe Holzinger  

Yeah. So I think what's important to clarify is that, range and energy density, those are what consumers want. But what automakers want is a reduction in costs. And really, that's what every sector wants. They don't want to pay too much for the battery. So some of these high energy density technologies that are really cutting edge and technologically incredible, some of them are really expensive, and it's hard to see how those costs can come down. And so there will likely always be some kind of market for those extremely high energy density technologies, but it's still a huge open question on whether or not those technologies will even be used in electric vehicles beyond the luxury vehicle segment. You even really see those different chemistries in an economy car. And I think from the past couple battery power day announcements by Tesla and Volkswagen, they're not planning on those high energy density batteries being used in most of their vehicles. They're looking at tailoring their vehicle battery strategy to some of these cheaper chemistries that are more robust to price bikes. 

And, to answer the other half of your question, when you're thinking about the impact of these automotive trends on other end uses for batteries, whether that's consumer electronics or energy storage, you see a couple different things. So for consumer electronics, that's a market that pretty much at this point scales with population growth. Everybody has a laptop, cell phone, some people have multiple, and the battery technologies for those systems are pretty stable. Those are not really where a lot of the cutting edge innovation really is at this point in the battery world. 

For the energy storage market, the energy storage market has fluctuated in what battery technologies it will use, depending on what's available, and how much they cost. And so this recent increase in LFP demand in the automotive industry, for example, has actually caused a shortage of LFP battery availability in the stationary storage sector. And this is definitely temporary. I don't really want to scare anybody –

David Roberts   

It's just manufacturing capacity, right?

Chloe Holzinger  

Right. I mean, if you think about it, electric vehicles are like 90% of the battery market. So if you are a battery manufacturer, and an automaker comes up to you and says I want you know, this huge amount of LFP batteries, are you going to go fulfill that order? Or are you going to go, “No, I'm committed to these other orders that are much smaller for these other particular applications.” Sometimes they'll commit to the energy storage contracts that they have, and sometimes they'll say, “Well, actually, this is really tempting, I'm just going to go with this much, much bigger order.” 

And there are a lot of efforts to increase manufacturing capacity for LFP batteries at the moment. But for the short term, first half 2021, it's been basically impossible for stationary energy storage companies in the US to order new LFP batteries for systems this year.

David Roberts

Interesting. Let's talk about storage briefly. In EVs, obviously, energy density is a big thing, because you want to go a long way. What are the sort of performance characteristics that you're selecting for, in say, a home storage battery–a Powerwall or some variant? What do you want out of that battery?

Chloe Holzinger  

The fascinating thing with the grid storage sector is that, unlike electric vehicles, every application is really different. Comparing an economy car to a luxury car, you might say, one person does city driving, and the other person likes to do long treks or whatever. But comparing a home energy storage system to a utility-scale solar plus storage system that's a gigawatt in scale, those are completely different systems, with completely different demands and needs. That utility scale system is probably going to want to cycle once a day, twice a day, maybe. And that's a lot more often than you would charge your car; that's a pretty heavy use case. And, in the US, we have a lot of land here, so footprint isn't really a huge issue. 

Whereas, in your home, you really want a small system that’s very safe because it's in your house, and you want to make sure, ideally, it's paired with a solar roof. I think Tesla right now has just said that they aren't selling any home batteries without solar. But that's probably not going to charge and discharge as deeply as a commercial, industrial, or utility scale battery.

David Roberts   

So for a big grid battery, then, maybe you don't care so much about energy density, because space is not as prized like volume is. It's okay to be a little bigger, and it's okay to be a little heavier as long as you're very resilient, or have a high cycle life, right? So, if I'm going shopping for a battery purely on cycle life, where do I look? Who's the leader there?

Chloe Holzinger

Yeah! Some of it's also just discharge rates. Really the only two battery chemistries right now that are really used in stationary storage applications are LFP chemistries and NMC chemistries, and not necessarily high nickel NMC like 811 formulations – it's like NMC 532 or 111. They're not the ultra high density, lower cycle life chemistries. 

Among those three chemistries, if you're talking the two different NMC formulations and the LFP, that pretty much covers the vast majority of stationary storage systems. There's much less diversity in chemistries in the stationary energy storage market, in part, because there's different needs than the mobility market, and a lot of the efforts to make new technologies for lithium ion batteries are focused on the needs of the mobility sector and not necessarily the needs of the stationary energy storage sector. 

And so you see that these non-lithium alternative batteries are almost exclusively targeting the stationary energy storage sector because there are so many discrete niche applications that maybe lithium ion isn’t best suited for. In an ideal world, one of these non lithium alternatives, would be able to find a place in it. So an example is some of this long duration seasonal storage that people are talking a lot about now. California, in particular, has been supporting these through grants, and various Community Choice Aggregators are supporting these through RFPs. Those types of seasonal duration, really, really low discharge systems, enormous systems for meeting those various occasional needs, [lithium batteries] are not appropriate.

David Roberts   

Enormous systems, that may only charge and discharge like, once a season - once every couple of months.

Chloe Holzinger  

Yeah. And so for those systems, lithium ion batteries are way too expensive. You could hypothetically, still do it with a lithium ion battery; it's technically feasible. But you would never want to – it would be extraordinarily expensive. And so you are seeing a bunch of different technology developers developing entirely different systems for long duration storage specifically, that are using various different kinds of low cost feedstocks. And they're claiming we'll be able to meet those types of needs at reasonable capital expenditures.

David Roberts   

Right, let's return to EVs real quick and look at a few of the sort of more hyped, cutting-edge technologies that are coming along, see if we can figure out if any of them are really going to change the game, as they say. 

Let's talk about one that I think everybody's heard about at this point, which is solid state batteries. Maybe just tell us, what is a solid state battery and why would you want to make one? And is it in fact going to [make a huge difference?] I mean, I've been immersed in batteries for weeks here and I have read an enormous array of very strong opinions about the future of solid state batteries, all of which are mutually contradictory. So maybe you can just give us your sense of sort of, what is solid state, why is it so hyped, and will it revolutionize batteries all over again?

Chloe Holzinger  

Yeah, yeah, definitely, there's definitely a variety of opinions here. And really what solid state refers to really just means that the electrolyte and separator in an all solid state battery are replaced with one solid material that you know, is non flammable, that doesn't use the same materials as today's incumbent electrolytes and separators do.

David Roberts   

We should just pause and note that most of the incumbent electrolytes are liquid, some form of goop– 

Chloe Holzinger

Liquid or gel.

David Roberts

–which tend to be flammable, among other things, which is part of the problem.

Chloe Holzinger  

Yes. That’s really where the safety concerns around lithium ion batteries come from. It's because of these flammable electrolytes.

David Roberts   

So you replace the electrolyte with a solid material that obviously gets you safety, since the solid material won't catch fire. But what else? What else does it do? 

Chloe Holzinger  

That's really it. That's the definition of a solid state battery. 

David Roberts   

But don't they also improve energy density, though?

Chloe Holzinger  

So this is where it gets tricky. Because for a long time, people thought that in order to use a lithium metal anode, which is really a much higher energy density than today's incumbent, graphite anodes, you really need a solid electrolyte, because when lithium metal anodes charge and discharge, lithium plates back onto the anode. And so there's a risk of the lithium plating unevenly on that anode.

David Roberts

Dendrites!

Chloe Holzinger

Yep. And these branch-like dendrites can short the system and cause the battery fires; you really don't want dendrites. 

David Roberts   

This was an interesting fact, I just learned in my research, which I'll insert here, is that using solid lithium metal as an anode actually preceded lithium ion batteries. And it was these problems, namely, the formation of dendrites and such, that actually led researchers to say, well, let's put graphite on top of the lithium. And that way the ions can nestle in the graphite or intercalate in the graphite. They won't be able to hold as many, but they'll be stable, and it won't have these problems of dendrites and etc. So it's sort of interesting that the solid metal anodes are coming back. Like, they were around in the 1970s, and they're coming back; it seems like everything comes back eventually in the battery world. 

Chloe Holzinger  

Yes. And lithium metal anodes are really the key to maximizing energy density in lithium ion batteries. And for a long time, a lot of people thought that you could only use them with a solid electrolyte. What we're finding now is that that's not necessarily true. You're starting to see a lot of other startups that are using lithium metal anodes with liquid electrolytes – Scion power has been doing it for a long time. And Cuberg, which was just acquired by Northvolt. These battery developers aren't using a solid electrolyte and are still achieving the same types of cell level energy density that the solid state battery developers using lithium metal anodes are also achieving.

David Roberts   

Well, why wouldn't you want to use a solid electrolyte though? Are there considerations governing why you choose one electrolyte or the other? 

Chloe Holzinger  

So the solid electrolyte benefit is that added safety, right? You're not going to get that added safety with any kind of liquid electrolyte.

David Roberts   

Right. I guess I'm just wondering, why isn't everybody sort of herding to solid electrolytes if they're safer? Is there is there a drawback of some kind?

Chloe Holzinger 

Yes, there are a few. The first electrolytes were made of this polymer called polyethylene oxides, I think PEO electrolytes, and these are solid. They're actually in use in vehicles today and have been for a while, in a few ride sharing vehicles, I think in Paris. But they need to be heated up in order to actually achieve the kinds of ionic conductivities, in order to basically allow the battery to charge and discharge efficiently. And that external heater impacts the total battery efficiency. If you have to use part of the battery output to heat itself, you're having less battery to drive the vehicle. That's one main issue with electrolytes is that room temperature ionic conductivity is difficult to achieve. It's difficult to make a solid state battery that can charge and discharge at reasonable rates at room temperature without an external heater.

David Roberts

Interesting. Is there such a thing in the world yet? I assume some researchers are on that.

Chloe Holzinger  

Yes. So that's really one of the first things that a lot of these solid state battery developers that you're seeing today have been focused on and working on, since they were founded. That was really their first starting goal. And so companies like Solid Power and Ionic Materials, they both claim to be able to have very competitive charge-discharge rates at room temperature. The other factor is, with any new battery technology, it's going to have a lower cycle life than one of these incumbents. And this is a case for solid state batteries, for lithium metal anodes, for some of these high manganese cathode chemistries that you're hearing about now. These are all new materials that are still in their development stages. And so because of that, they're not 100% optimized for full functionality yet.

David Roberts   

And that's just a matter of learning by doing right–just making a bunch of them and figuring out incremental improvements.

Chloe Holzinger  

Exactly. Science is a slow process. And, some of these batteries are only able to achieve 500 cycles, for example, which is much less than, you know, the 1000 cycles plus that you would really need to be qualified for use in an Electric Vehicle. All these companies have been getting much better over time, Bbt that's still a weak area for solid state batteries.

David Roberts   

So it sounds like a lot of the hype around solid state is less about the solid electrolyte in particular, and more about the combination of a solid electrolyte with lithium metal as an anode. 

Chloe Holzinger

Exactly.

David Roberts

That's what people think is going to be the next revolution, or whatever.

Chloe Holzinger  

Right. So if you take a look at QuantumScape, for example, QuantumScape uses this lithium metal anode. And it claims that it has spent these past many years of its development really optimizing and solving the dendrite issue. But QuantumScape uses a solid ceramic separator, yet also uses some liquid electrolyte at the cathode. So it's not what I would call an all-solid state battery. It is a lithium metal anode battery, but not all solid state. And it's because it uses a solid ceramic separator, it can be lumped into some of the semi-solid batteries. These different terms kind of get conflated. 

David Roberts

Semi-solid state.

Chloe Holzinger

Yeah, yeah, I mean, really. So, the lithium metal anode, that is the part that enables this huge energy density increase that QuantumScape has been able to show through its data that it’s shared.

David Roberts   

It's a little weird to me, then that solid state gets all the hype, since it's really the lithium metal, it's the metal anode that's really giving you the sexy kind of performance boosts that you want in the solid state. The electrolyte is a little bit of a footnote to that. Why did things work out that way? Is it just people not being careful with their terminology?

Chloe Holzinger  

Yeah, it's a little bit of an artifact from when people thought that you needed an all-solid electrolyte for a lithium metal anode. And so “solid state battery” really referred to the combination “lithium metal anode” and “solid electrolyte”. But you're seeing companies now that are developing lithium metal anode batteries without solid electrolytes, and you're seeing solid electrolyte developers developing batteries with a graphite anode. So it's not really the uniform term that people assumed it would be when it started becoming part of the lexicon two to three years ago, 

David Roberts   

I'm just gonna clarify this for readers who are confused. You have a lithium metal anodes, which can be coupled with either solid or liquid electrolytes. And then you have solid electrolytes, which can be coupled with either lithium metal anodes or traditional graphite. And so they're sort of separate in that you got a matrix of possibilities. But the solid state that everybody's excited about, the one that's supposedly setting off this whole new round of innovation and everything, that's mostly about the lithium metal metal anode involved. 

Chloe Holzinger

Yes, yes. 

David Roberts

And so the lithium metal anode holds more lithium ions. And if you can overcome the dendrite formation problem, you just get a ton more – they're saying double the energy density, which would mean theoretically, double the range for an electric vehicle. And there's a bunch of these that are supposedly, just over the horizon, right, like mid 2020s? Is all the really sexy hype stuff still out a few years? Are any of these in use yet?

Chloe Holzinger  

Yeah. A lot of these different battery technologies are still pretty far away from commercialization. So, probably the most aggressive companies are saying that they'll be able to use solid state batteries in an electric vehicle by 2025. And that's pretty aggressive when you're thinking about how long it takes to get a battery qualified for use in a vehicle by an automaker. And also, when you're thinking about the scale in production, if you're going from a pilot plant to a mass produced vehicle, that's a huge jump in production capacity. And that's a whole different hard part of this whole equation. You can make the best battery in the world at lab scale, but that doesn't really mean anything if you can't make it in a cell that can integrate into a pack for an electric vehicle, and then produce the same high quality battery over and over and over again for many vehicles. That's a huge stretch.

David Roberts   

Yeah. One of the sorts of considerations I keep stumbling into is, you've got, at this point, a pretty enormous manufacturing capacity built up for conventional lithium ion batteries, which means just a lot of learning by doing a lot of scale, and just a lot of built infrastructure. And so one of the things I see a lot is, if you're going to get a competitor to conventional lithium ion batteries, it's probably going to have to be able to make use of existing manufacturing capacity. In other words, like, you can't just require a whole new set of factories, whole new kinds of factories. So I'm wondering, of these kinds of solid state batteries, are any of them going to require new factories? Or are they going to be able to make use of existing manufacturing techniques?

Chloe Holzinger  

The startups are really pursuing mostly one of two different strategies. So the first strategy is really becoming a material supplier for incumbent cell manufacturers and producing their solid state batteries on today's manufacturing lines. And as you said, that really is able to leverage existing infrastructure, which is phenomenal; you can really access that very quickly if you can integrate yourself into or integrate your technology into these manufacturing lines. That's a great way to be able to make a lot of your batteries quickly. Also, some of these manufacturing lines – these costs quite a lot of money to build. So many factories and automakers aren't going to want to pay for new factories that require new facilities. When you have governments really throwing billions of dollars at a single factory, if you consider all the amounts of money that the European Union and various European countries have given to sell manufacturers to build factories within Europe, it's incredible. So that's one strategy. 

The other strategy is, if the battery company is unable to integrate its technology with today's manufacturing lines, there's really no other option except for that company to become a cell manufacturer themselves, and build the relevant manufacturing lines using whatever specialized equipment that they need. They're going to have to do that themselves.

David Roberts   

And that, to me, just sounds daunting. I mean, to me, it almost sounds more challenging than the sort of scientific work of developing a new chemistry, just the nuts and bolts work of becoming a large scale manufacturer. This other manufacturing process has been around for decades, and it's been coming down at cost for decades. I mean do you see any of those possibly getting anywhere or succeeding?

Chloe Holzinger  

Yeah, I mean, I don't want to pick favorites, or say that anybody's absolutely not going to succeed, because I could absolutely be wrong, and I don't want to insult anybody. But I think one of the factors that is supporting groups in the second category that want to make batteries themselves – because you're right, this is in a lot of ways even more difficult than the actual battery development in the first place. But there are huge amounts of money out there looking to support solid state battery development, whether you're talking about automakers, or cell manufacturers, or chemicals suppliers, or now, financial institutions. SPACs are here for at least the near term, and the amount of money available to companies looking to go public by merging with a special purpose acquisition company, or SPAC is just phenomenal. You have a valuation of a billion dollars, which used to be a lot of money for a startup. And suddenly, overnight, go to a $10 billion valuation.

David Roberts   

Yeah, it's got a bit of a bubble feeling, as I read around solid state. Do you think that's right? Do you think there's gonna be some high profile crash and burns happening at some point?

Chloe Holzinger  

I mean, I think it really depends on the company. Not all the SPACs, the companies in the electric mobility space that have chosen to go public this way, they're not all equal. There are some companies that are already making revenue, and that haven’t really changed their business plan at all since going public. They're just continuing ahead and saw an opportunity to make a lot of money really quickly, and who am I to blame them for that? I actually support some of that strategy in part because there has been a lot of government support for electric mobility technologies in a lot of countries but not really in the United States over the past four years, since 2016. So a lot of these developers and these companies that are operating in this space, if they're targeting a market that they're expecting will grow with these kinds of exponential rates that automakers are expecting, they want to grow quickly in order to meet that demand. And going public via SPAC is a quick way to make that money to scale your process and go get that market. And you don't want to miss that opportunity.

David Roberts   

There's a lot of money floating out there. 

Chloe Holzinger

Yeah.

David Roberts

Let's talk about one or two more of the areas of innovation. We hit solid lithium metal anodes, which gets you a bunch more energy density. We talked about solid electrolytes, which gets you safety – no more fires. One of the other ones I see come up a lot that Tesla is leaning heavily on, and that I know some people are very excited about, is using silicon as an anode. Can you tell us a little bit about about who's doing that and why?

Chloe Holzinger  

Yeah! So Silicon is a little bit different from these other different technologies, in that it is much closer to commercialization than either solid electrolytes or lithium metal anodes.

David Roberts   

You mean silicon anodes specifically? 

Chloe Holzinger  

Yes. And really when I say silicon anodes, for the most part, I’m meaning silicon graphite composites. These won't really be pure silicon anodes. I’ve really yet to see a pure silicon anode battery that is cost competitive with lithium ion batteries. 

David Roberts   

Why is the graphite still in there? What goes wrong when you add more and more silicon? Like, why is it difficult? 

Chloe Holzinger  

It