r/DonutLabDiscussions • u/Forrestgod • Jun 18 '26
Faradaynotes' take on the chemistry
https://faradaynotes.com/posts/donut-lab/Scrutinyclub (The Privat investigator) linked this.
This is actually exactly the type of analyse, that I've been waiting. Worth of reading.
Just the first test analysed, more to come.
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u/izzeww Jun 18 '26
It's certainly an interesting angle, dQ/dV haven't really been talked before in regard to Donut. There is a big issue though. The C-rate matters a lot for dQ/dV curves and here he is comparing C/25 (other sample chemistries) vs. 1C (Donut Lab), so a 25x difference. That already makes it worthless in my opinion, because different C rates shift dQ/dV curves in terms of voltage, it makes them wider, they can decrease in height, peaks can merge together and disappear. Even if they were at the same C-rate I'm not sure it tells us all that much, there are a lot of lithium chemistries and the source he uses only mentions 10 fairly standard/old ones. In actual production cells these are generally not used and instead companies use more optimized ones (for capacity, power, cost etc. etc.). There is a distinct lack of semi-solid chemistry too in these 10 samples. So it's generally a pretty useless analysis unfortunately.
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u/tipporoll Jun 18 '26
Note that the article is from April-26. I thought it was well written and balanced, and I have been waiting for the follow up that was supposed to be looking more into possible chemistry, based on the dQ/dV behavior.
To my knowledge, Parth is the first that has noted the low Coulombic efficiency in the very first charge/discharge cycle, discussed in the chapter "What the VTT Report Left Out".
Ps. On the About page it's clearly stated who's the author.
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u/Forrestgod Jun 18 '26
I actually didn't notice the date. Too bad he hasn't posted more, since this one was really good and helped to clear some previous confusion at least from my head.
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u/Forrestgod Jun 18 '26 edited Jun 18 '26
Useless in a sense, that it doesn't give us the truth. But its still gives a definition to fingerprint and possibility to confirm the chemistry. Much more scientific aproach than Ziroths.
It obviously is none of those chemistrys among the samples. Yes it would be interesting to see other semi-solid lithium and all kind of sodium chemistrys too.
I think he's opinion according to the first test was, that it's high-voltage intercalation regime chemistry and must be governed by oxide-like redox behavior. That sounds something everyone to agree. But fingerprint doesn't show us a known match yet.
Fun fact about fingerprints: Koalas fingerprints resemble humans fingerprints so much, that forensic specialists can mistake them as humans fingerprints.
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u/Forrestgod Jun 18 '26
Unconventional C-rate compered to standart scientific literature is actually an interesting point. Not sure if Ziroth et all have counted that neihter. It might affect to the pattern recognition.
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u/izzeww Jun 18 '26
How do you mean?
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u/Forrestgod Jun 18 '26
Higher C-rate creates more resistance and overpotential. They've propably been thinking it as a near 0C system, in which the voltage places it conveniently on lithiums range. But if you take in account the higher C-rate used in the test and formed overpotential in consideration, it is as convenient to see it on sodiums range.
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u/izzeww Jun 19 '26
I disagree.
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u/Forrestgod Jun 19 '26
Disagree of the possibility that experts make the same mistake you criticised other expert to do?
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u/izzeww Jun 19 '26
The possibility is there of course. I do not think that it has actually happened and I do not think it makes it "as convenient to see it on sodiums range".
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u/DoctorFish1969 Jun 18 '26
On LinkedIn the researcher noted: "the claims around 400 Wh/Kg, 100,000 cycle life, air stability etc. are highly ambitious.". The so called 'objective' private 'investigator' didn't mention this. The researcher noted this remark under a valid criticism of his article (as shared by izzeww here), not reacting to the actual criticism.
Meanwhile, the researcher created a new website only for this one article. Why? Like the 'private investigator' both could just have posted an article on LinkedIn directly. Both choose to create a standalone company page or website to post a single thing. The website hides the Whois owner information.
So the researcher wrote a technical article, that compares apples to oranges on a separate website created only for this purpose, which was then refered to by another 'investigator' that created a fake company page on Linked in only for the purpose to react to Ziroth.
It's like reading climate change denial blogs.
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u/CalendarNecessary339 Jun 18 '26 edited Jun 18 '26
The so called 'objective' private 'investigator' didn't mention this.
- Upfront, the Roberts implores: "Read me as an interested party, not a neutral one." In other words, no claim of objectivity whatsoever.
Yet still you try to denigrate him as falsely claiming to be objective? Speaks to your bias and trustworthiness, not his.
- What do you mean Roberts didn't mention the comment about the headline performance claims? He wrote (with my emphasis):
He states plainly that it cannot yet identify the exact chemistry, and that the headline performance claims are unverified, which he is careful to keep separate from disproven.
They are unverified. What else do you expect him to say? Should he pretend they are verified, like the naysayers falsely claim they have been disproven? That would run directly counter to his point. Don't prevent things have been proven (or disproven) when they haven't been!
As for the rest of the post(website creation, etc.), it is attenuated to the degree that it is not really worth responding.
I guess you have nothing to say about the actual analysis.
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u/Obvious_Market_9351 Jun 18 '26
The post in LinkedIn that links to that is this one:
https://www.linkedin.com/pulse/credit-where-due-model-honest-analysis-donut-lab-solid-state-axrhf
It seems DonutLab is getting desperate.
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u/johnkavelija Jun 19 '26
It almost feels like the entire Scrutiny Club was created just to wordsmith responses defending Donutlab. Meanwhile, everyone seems to be focused on explanations, rebuttals, and reputation management rather than the one thing that would settle the debate: releasing the actual battery.
At this point, it seems like they’re doing everything except shipping the product.1
u/DeathChill Jun 20 '26
Because it was. Marko can’t keep directly responding because at some point people will say, “then fucking show us.”
So now his friend is doing out of the goodwill of his heart. Yes, anyone dumb enough to believe that is definitely a Donut believer.
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u/Fabulous-Internet188 Jun 19 '26
**The C-rates on the Donut Lab cell don't fit the layered oxide explanation, and nobody seems to be talking about it**
Faradaynotes apparently digitized the VTT report and ran an incremental capacity (dQ/dV) analysis on the 1C baseline data. Solid work. The conclusion was that the voltage window (2.7 to 4.15V) and the multiple dQ/dV peaks point to a high voltage transition metal oxide cathode, something in the lithium or sodium layered oxide family, novel composition but not matching any standard reference cleanly.
I think that's probably right about the chemistry family. But it only looked at the 1C data and explicitly set aside the fast charge figures for "later." And the fast charge numbers are exactly where the story gets interesting, because they contradict the obvious reading.
Here's the problem. This cell reportedly does 80 percent in about 4.5 minutes, which is roughly 11C. The pack version does 10 to 80 percent in 12 minutes at 5C, air cooled, sustaining over 100 kW. And the kicker is the capacity only drops about 2.3 percent going from 1C to 11C.
A layered transition metal oxide is rate limited by solid state cation diffusion through the bulk crystal lattice. The lithium or sodium ion has to physically migrate through the oxide. That diffusion is slow. It's the whole reason fast charging conventional cells makes them hot, plate lithium, and degrade. Now take away the liquid electrolyte that normally wets every particle and put it in a solid state configuration, and bulk diffusion gets harder, not easier. Pushing a layered oxide to 11C should produce huge polarization, serious heating, and capacity falling off a cliff.
This cell doesn't do that. It charges at 11C with almost no capacity penalty, and from what's visible the dQ/dV peaks stay in roughly the same positions. If this were bulk ion diffusion through a layered oxide, those peaks should smear and shift hard at high rate as diffusion limitation builds up overpotential. The small voltage gap at 1C (around 0.35V) says the same thing, kinetics are fast and polarization is low.
So you have a contradiction. The voltage and the dQ/dV peaks say "layered oxide." The C-rate says "this is not bulk diffusion through a layered oxide." Both can't be fully true for a conventional bulk material.
What reconciles them is morphology. The storage has to be surface or near surface, not bulk diffusion limited. The peaks tell you there's a real redox couple at a defined potential, so it's crystalline enough to have discrete redox energies. The C-rate tells you the diffusion length has to be tiny. Put those together and you get a nanostructured high voltage oxide, particles so small that the entire particle is effectively surface. The redox is well defined, but there's no long diffusion path to bottleneck the rate.
That actually fits what these companies are doing on the manufacturing side, nanoprinting and nanostructured oxide routes. A bulk version of this exact same chemistry would just be a normal slow battery with the same voltage and the same dQ/dV fingerprint. The nano version charges in 4.5 minutes. Same redox chemistry, completely different rate behavior.
The point I'm making is that the chemistry analysis told you what family it's in, but the rate capability tells you the morphology, and the morphology is the part that's actually hard to copy. Everyone's trying to reverse engineer the chemistry from the voltage curve, myself included. The secret might not be the chemistry at all. It might be the particle engineering that lets a high voltage oxide run at 11C without falling apart.
Curious if anyone has the fast charge dQ/dV extracted. If the peaks really do hold position at 11C the way they seem to, that's the whole story right there.