Liar, Liar, Battery Supplier

Edition #010: A conversation with Charlotte Hamilton, CEO of TAF Carbon

Welcome back to CNT Dispatch, and a warm hello to all the new subscribers. Today's edition is a bit of an experiment: an reasonably honest attempt at being a neutral source on carbon nanotubes. We are others see the potential, and we're firmly in the believers' camp, but the field is better served when we're willing to be critical too.

So with that, edition #008 got some pushback. The piece argued CNTs are going from “nice optimisation” to “structural necessity” across every next-generation battery chemistry. Alvin’s response was fair: talk to someone who’s actually been in the trenches. Enter Charlotte Hamilton.

Charlotte has been running chemistry startups for 20 years. She founded Conamix (a silicon anode company that pivoted to sulfur cathodes) out of Cornell and ran it for a decade. She’s now CEO of TAF Carbon, a sister company to TrimTabs inside the Endeavour Ventures ecosystem, making fire-resistant carbon foam for buildings. Endeavour is also the lead investor in Tiamat, the French sodium-ion company Charlotte flagged on the call as one of the most promising new chemistries going. She has also deliberately avoided working with carbon nanotubes her entire career, until recently.

Not anti-CNT though. She wants to use them in what she’s building now. But she’s watched the material come across her desk for 20 years and watched almost everyone fail, and the view from that position is worth listening to.

What I Learned

1. A battery is four problems pretending to be one

Battery chemistry is so unforgiving because power, energy, lifespan, and fit (manufacturability plus cost) all have to work together inside one system. Semiconductors are hard, but at their core they’re doing one thing. A battery is an “almost biological system” of cathode, anode, electrolyte, and separator, each with its own chemistry constraints and all of them talking to each other. Change the cathode to boost energy and you might break the interface with the electrolyte. That’s why new chemistries take 20 years to commercialise, and most of them don’t.

2. “Liar, liar, battery supplier” is the industry’s 120-year-old open secret

Thomas Edison said it in 1900: the chemical energy storage business is filled with liars. Nothing has changed. You can make almost any chemistry look brilliant on one parameter, massive milliamp hours per gram on the cathode, beautiful cycle life, wild power density, while ignoring the other three. That single-parameter cherry-pick is how many first-wave CNT battery company, many early silicon anode, many solid-state demo got funded. But the data gets measured on a toy system has nothing to do with the battery in your phone.

3. The bullshit test is multi-layer pouch cell data

Coin cell data is not data. A coin cell has excess electrolyte, one layer, and no real geometry constraints. If a company shows you coin cell data, walk away. The real test is a multi-layer pouch: 10 to 20 stacked sandwiches with limited electrolyte, the same format that goes into a phone or a car. You want to see power, energy, cycle life, and cost all measured off that same system.

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The Conversation

I. Why She’s Contrarian on Batteries

Lawrence: You’ve been running chemistry startups for 20 years. Give me the short version of how you got to TAF.

Charlotte: I founded Conamix out of Cornell. We started as a silicon anode company, switched to a sulfur cathode company. There’s a UK publication that tells the whole story of that pivot, and a Wall Street Journal piece I’d recommend on how hard it is to judge hype versus reality in the battery world. I ran that for 10 years. Before that I was looking at new technology in chemistry from about 2004 onwards. Now I run TAF Carbon. Different material, different problem. And Alvin and I are buddies, our companies both came into the Endeavour Ventures ecosystem within a few months of each other.

Lawrence: Let me say something stupid so you can reflect it back. In my previous fund we didn’t invest in any battery chemistry companies even though we had a material scientist on staff, and my heuristic is similar to semis: it’s easy to come up with a theoretical new design that solves X or Y, there are 100 theoretical designs, and the real bottleneck is making it at a price that competes with lithium.

Charlotte: Sure. But the bottleneck is more complex than that. Price is a huge driving factor, but batteries have to have price, performance, and fit. All three, together, inside a complex system. I’d look at semiconductors and say, at their core, they’re doing one thing. A battery is doing four things at once.

Every battery is a sandwich. A cathode on one side, an anode on the other, electrolyte in between, and a separator in the middle. The ions have to go from one side to the other, whether they’re sodium or lithium. You need capacity on the cathode, capacity on the anode, ionic solubility in the electrolyte, and some things have to pass through the separator while other things don’t. Depending on your chemistry, you’ve got an almost biological system.

The problem is that you end up with high performance on one aspect and convince yourself you’ve got the greatest thing ever. You’ve got really high milliamp hours per gram of cathode material? Great. But the interface between your cathode and your electrolyte might be broken. Maybe it’s too strong and now you’ve got no cycle life. Maybe it’s too weak and lifespan drops off the first time you use the battery. All of these subsystems have to work together.

“There’s a saying in the battery world. Liar, liar, battery supplier. Everybody knows it, nobody says it.”

Lawrence: The Edison quote.

Charlotte: Edison said the chemical energy storage business is entirely filled with liars. I’m misquoting him a bit, Edison said it better, you can look it up. From the very earliest time, when you were storing chemical energy, you faked it in one way or the other. You could say, look at all this power I can get out. Fine, you get all the power out, but you can only do it for a very short period, so you’ve got very low energy. Or you say, look, I can cycle it a thousand times, isn’t that great, but you’ve done it at very low energy. You can take one piece of the system and make it look brilliant to an inexperienced observer. That affects investors, it affects buyers. And then getting to market is a whole different thing.

As a result, the lifespan from new development to full commercial scale is very long, and almost everything fails along that path.

Lawrence: Even if you got the chemistry right, wouldn’t cost still kill you? Lithium-ion keeps falling off a cliff. If you hit market in five years, who knows what lithium costs by then.

Charlotte: Lithium-ion has been dropping in cost per kilowatt hour by about 5% a year, and it keeps doing it. There’s a floor based on the chemistry and materials involved, and eventually it’ll hit an asymptote and stop falling. If you’ve got a step-change improvement that’s 30% better than the current lithium-ion lowest price, then yes, potentially interesting. It’s measured in dollars per kilowatt hour. So if you can improve the kilowatt hours without changing the dollars, you’ve done something. But you’d have to have a price-performance improvement of over 30% to even consider going into the development costs.

And then there’s scale. This chemistry isn’t just complex, the scale of your competition is massive. People have tried to build competing gigafactories outside China and failed. Korean, Chinese, some in Japan, a few in the US. A VC would say it’s approaching a fully built market. A new chemistry is going to have a really hard time.

II. Twenty Years of Avoiding Carbon Nanotubes

Lawrence: Have you ever used CNTs in any of your companies?

Charlotte: No. I’ve deliberately avoided them.

Lawrence: Tell me why.

Charlotte: I started looking at companies like this in 2004. CNTs were the next big thing. There was a whole nanomaterial bubble, lots of nanomaterial companies got invested in and never actually succeeded. CNTs, really novel high-performance material, extremely hard to make very long, extremely hard to make at very high volume. So anything that came across my desk and said, “Charlotte, you should help us start a CNT company”, I basically ignored it. I looked at it as always just around the corner. I let other folks work on that. I was first approached about a CNT company in about 2009. It’s been a long time. I worked on other polymers, batteries, biotech, and now carbon materials.

What’s unique about what Alvin is doing is he’s figured out how to produce them very long and at higher volume. Aggressive chemical engineering to get there. I think it’s got a lot of potential, and I’d love to use these materials in what TAF is doing. We talk all the time.

Lawrence: So on one hand, CNT pitches have always claimed extraordinary performance, 10x better than copper on electrical conductivity, magical thermal numbers, whatever. That would sound miraculous if it came out of a new AI materials discovery tool tomorrow.

Charlotte: Oh God. Don’t invest in AI for materials discovery. It’s a bad idea.

Lawrence: Not me personally, but you know, it’s a whole category.

Charlotte: AI materials science is a very fast blind robot spinning around in a room trying to run into a good idea. I’d much rather work with some of the world’s most amazing chemists, people like Alvin, who understand what’s going on. AI is a tool. Discovery is bunk without people to drive it. But that’s a rant.

The point on CNTs stands though. If AI discovered carbon nanotubes tomorrow, you’d have a new startup raising $100 million on day one. But it’s been 25 years. That’s the real timeline for a wonder material going from lab to commercial scale. And I think CNTs are finally coming to fruition. I’m excited about the future for TrimTabs.

III. The Tradeoff Nobody Talks About

Lawrence: In the batteries edition I wrote that “for high-silicon anodes at scale, there is no commercially viable alternative to carbon nanotubes.” Is that true?

Charlotte: Say that again.

Lawrence: For high-silicon anodes at scale, there’s no commercially viable alternative to carbon nanotubes.

Charlotte: I can’t weigh in, honestly. I know silicon anodes well, I’ve made them before with my own hands, but I haven’t been close to the state of the art in probably 10 years. I don’t know exactly how CNTs and silicon anodes interface at that scale now. Silicon anodes are really interesting. Multiple companies working on them at scale. I just can’t tell you if CNTs are the only answer.

Lawrence: Fair. Different angle then. The mental model I’ve been using is that CNTs in batteries are a drop-in, you sprinkle a bit in to improve performance, similar to how they’re used in concrete. If that’s right, where do you imagine CNTs actually have to live in a battery?

Charlotte: Go back to the four factors. Power, energy, life, and fit. Increased conductivity is going to increase your power. So CNTs are going to matter around power output. But I’m not sure which part of the battery the bottleneck is in, and it’s different for different chemistries. Solid-state batteries are all the rage right now. Solid electrolytes, higher energy densities, you might have a conductivity limit where increased conductivity matters more. But I couldn’t tell you which part of the battery that limitation is sitting in.

It’s not the wire coming out of the battery. It’s not the current collector, that’s aluminium or copper. You get to the cathode, and here’s the problem. If you have a higher electrical conductivity cathode material, did you just lose how much energy you can store?

Lawrence: Because the lithium ions have to find a home in the cathode.

Charlotte: Right. Lithium ions have to intercalate into the crystal structure. You’ve got to store a lot, that’s energy. And then you’ve got to get power, how fast you can get the energy out, that’s where increased conductivity matters. If you drop a carbon nanotube into that crystal structure so you can get the electron out faster, did you just block up a bunch of space that could have held a lithium ion?

This is the trick. I haven’t done the experiment. You could build a battery with a CNT-infused current collector that excels at getting electrons out. Awesome. You’re using CNTs instead of regular graphitised carbon. But did you just sacrifice energy for increased current? And you replaced something that was super cheap with something that is traditionally really expensive and hard to make. That’s the question.

“It’s easy to gin up a positive result in one of the four things. And it’s been that way for 120 years.”

Lawrence: That’s useful, because it’s the same pattern you just described. Ace one factor, lose on another, and nobody notices until the pouch cell fails.

Charlotte: Yes. The people who know the answer are the electrochemists actually in the cell, engineering the system. I trust them. I’m not in the battery world anymore. I worked in it for a long time.

IV. The Tiamat Exception

Lawrence: Is there a company that’s knocked down enough of these factors to get close to real volume production outside of lithium-ion?

Charlotte: Tiamat. Another sister company in the Endeavour ecosystem. Sodium ion. Lower cost on the basic ion, sodium is much deeper than lithium. They’ve got some phenomenal performance data, they’re the real experts. Their published strength is C-rate, how fast you can charge and discharge. It’s phenomenal. Because of that, they have a really strong position specifically for data centres.

Lawrence: That’s the use case everyone wants right now. You could sell to anyone but you’d probably pick data centres.

Charlotte: Right. Sodium-ion has been something people tilted at that windmill for a long time. What’s different about Tiamat is the scale of the improvement on C-rate. That makes it genuinely viable.

For context: Tiamat’s published specs show charge/discharge rates exceeding 60C, roughly 20-60x faster than typical lithium-ion. Sodium-based chemistry, free of lithium, cobalt, and nickel. Endeavour is the exclusive distribution partner for data centre deployments.

V. The Multi-Layer Pouch Cell Test

Lawrence: Last one. You’re a deep domain expert and even you say you don’t know unless you’re in the weeds with the electrochemists. For an average reader trying to assess whether a battery company is real, what’s the heuristic?

Charlotte: Real data off a multi-layer pouch cell.

Lawrence: That’s specific. Good. Go on.

Charlotte: Real data on power, energy, life, and cost. Manufacturability. All in the same system. Coin cell data is typical, and it’s nonsense. A coin is very small, it’s got an excess of electrolyte in there, it’s just not a fair system. An actual battery, the one in your phone, is a multi-layer pouch cell. 10, 15, 20 layers of stacked sandwiches.

Those stacked sandwiches have a limited amount of electrolyte because you can’t have a huge bath of electrolyte in a pouch cell. You need to see, on a full multi-layer pouch, how much power you’re getting, how much energy, what the cycle life looks like. I want a graph of energy per cycle. What C-rate did you run that cycle at? Did it last to 80% charge over several thousand cycles, depending on what the battery is doing? The battery in your Ferrari has different performance than the battery outside your data centre. But you’ve got to see performance on a multi-layer pouch, of all those things, off the same system.

“If you see one coin cell of data, just walk away. If it’s milliamp hours per gram in isolation, walk away. That’s not useful in the full system.”

Lawrence: Before multi-layer pouch data, it’s dreams.

Charlotte: It’s dreams. And the industry knows it. That’s why the saying exists. You’ve got to see complete data off a complete system, and almost no one leads with it because almost no one has it.

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Thanks, as always, for reading the CNT Dispatch. This is the second long-form interview I’ve run, and honestly, it’s the one that’s forced me to sit a little uncomfortably with my own Edition #008 take. Charlotte has, after all, watched 20 years of nanomaterial pitches come and go, and that’s the sort of perspective that’s genuinely worth taking seriously.

So where does that leave us? Well, CNTs work on paper. They also work in specific systems. But whether they’re actually essential at scale, that really comes down to a set of questions the battery industry isn’t all that willing to answer in public.

Which brings us to the test, really. What you want to see is multi-layer pouch cell data. Power, energy, life, cost, all measured off the same system. Coin cell data, frankly, is not data. Say it with me next time a battery deck lands in your inbox.

And on a related note, Tiamat is going straight onto my list. Sodium-ion, 60C, no lithium, no cobalt, no nickel, sitting in the same Endeavour ecosystem as TrimTabs and TAF, and pointing right at data centres. Probably worth an edition of its own, in due course.

In the meantime, if you’re working on a silicon anode, solid-state, sodium-ion, or lithium-sulfur play and want to push back on any of this, do reply to this email. More than happy to be wrong online, again.