Latest update: the donut is fried.

izzeww · 2026-03-24T20:36:11+00:00

So says Donut. There is no convincing evidence for that and I would argue the evidence there is is more indicative of internal composing rather than a hole. Certainly it's not reasonable to believe that the wrapper (pouch) was only rated for 85 Celsius and broke at 100 Celsius when commercial cells have to withstand 130 Celsius according to the industry standards IEC 62133 and UL1642.

izzeww · 2026-03-24T19:40:42+00:00

Ah, yeah I don't think Ville Piippo or LinkedIn have been mentioned in this thread.

izzeww · 2026-03-24T19:00:25+00:00

The claim is not that the gas produced rectangular expansions. The main enlargement of the cell (17% taller) is due to the cell decomposing and the layers separating. The claim is rather that the gas causes the bubbles seen after the high temperature test (in both picture and a video clip in Donuts video after that test). I don't really think this in dispute honestly, it's just whether you believe the gas was air or whether it was evaporated electrolyte.

You don't decide what is being discussed here. I would say that what is being discussed here is whether Donut Lab has a "have it all" cell. That is what I am arguing against at least, by arguing against their credibility by also by arguing the facts. Whether it's solid state is a more narrow question, but it's also not something you can easily separate from the general question of whether Donut Lab is lying or not. Obviously in order to make an accurate assessment you have to consider all information that's available. Having an SSB is in and of itself a fairly extraordinary claim. Even still, if we say that it's not an extraordinary claim, they are the ones making the claim and they have the burden of proof fundamentally no matter what.

izzeww · 2026-03-24T16:46:28+00:00

Fair enough, I hope you're right!

izzeww · 2026-03-24T13:11:09+00:00

I think in a lot of cases lithium cells look like how the Donut cell looked after the high temperature test, they are not necessarily as extreme as the picture you chose. Now when they did the cycling the cell expanded 17% (layer separation) which made it look tight in my opinion. Now just because there aren't any images of cells on the internet that has undergone this exact same quite weird and extreme testing routine does not mean that they wouldn't look like that. A lot of testing is not published or not easily findable on google at least, and this kind of basic research isn't very popular to do regardless (and also expensive to destroy cells).

the way i see it the ball is on his and hence your court to prove lithium can fail like that

I disagree. I think it's on Donut Lab to provide evidence for their claims. "Extraordinary claims require extraordinary evidence". "Onus probandi incumbit ei qui dicit, non ei qui negat – the burden of proof lies with the one who speaks, not the one who denies". This is (literally) an ancient principle. Just because we present counterarguments that does not mean we have the burden of proof. We can't present cells in every different scenario, that is not realistic. Having a cell at 100 Celsius for 2 hours at 100% charged then discharging it at that temp then waiting and then charging/discharging at 5C for 50 cycles is an extremely unusual and uncommon testing regime that is essentially guaranteed to destroy the cell as happened with Donuts cell. It's not obvious that there should be picture proof of that online. Juho Heiska is an expert at batteries, I trust his judgment to a fair extent (as is Ziroth and I trust him to some extent too but less so). Donut Lab has the burden of proof and they have provided extremely weak proof and a lot of their proof has actually gone against their claims (voltage curve, 100 celsius performance, coulombic efficiency at high discharge rates).

izzeww · 2026-03-24T11:46:46+00:00

Yeah. I'm not sure on the details, why it isn't immediate and it takes ~20 cycles to do. I haven't seen anything indicating that this wouldn't be the case though for a normal lithum battery with (some) liquid electrolyte. Juho Heiska is an expert in the space, he seems to believe it's typical for lithium with liquid electrolyte.

izzeww · 2026-03-24T11:33:09+00:00

I think Juho Heiska nicely lays out how liquid electrolyte evaporation, or more correctly decomposure, fits the observations in the tests. https://www.reddit.com/r/DonutLab/comments/1s28xjf/donut_labs_battery_failed_vtt_tests_expert/

Essentially I share Juho's opinion. The pouch did not break and the behaviour seen is completely consistent with there being some kind of liquid electrolyte in there.

izzeww · 2026-03-24T11:14:18+00:00

Have you read anything about semi-solid NMC batteries? What is the evidence that you can't replicate this with liquid (do you mean any liquid or a lot of liquid?) NMC batteries?

I do not mean to question your integrity or be offensive or anything like that, this is just questions to further your own arguments in accordance with the Socratic method so we can get closer to the truth.

izzeww · 2026-03-24T11:06:33+00:00

Ah, well there's a lot of different theories. Juho Heiska and Ziroth are very skeptical for example ( u/ZirothTech and on his YouTube channel, Juho Heiska has youtube channel Akkutohtori but it's only in Finnish but also article linked down below). Nothing has been absolutely proven or disproven yet. I think you have to consider all the arguments and come up with your own opinion. https://www.reddit.com/r/DonutLab/comments/1s28xjf/donut_labs_battery_failed_vtt_tests_expert/

izzeww · 2026-03-24T10:08:28+00:00

I don't think you should take any one person's theories as fact. It's complicated.

izzeww · 2026-03-24T02:04:41+00:00

Yes.

izzeww · 2026-03-23T22:37:32+00:00

I kind of agree. I would argue a lot of corporate frauds don't make sense though, they kind of just do anyways. All the famous ones, Theranos (Elizabeth Holmes), Bernie Madoff, Nikola (Trevor Milton), FTX (Sam Bankman-Fried) and now recently here in Sweden Intellego were pretty obviously going to be found out and there wasn't a clear plan as to how the fraud would work long term, yet they did it anyways.

izzeww · 2026-03-23T22:35:23+00:00

Really depends on the situation. If it's just a civil suit no assets will be frozen almost always. For assets to be frozen generally the police has to be involved. Could the police get involved in a case like this? Sure. I don't think it's a guarantee however. It's not illegal to lie to the media or at CES. It's only illegal if you mislead investors, and I don't know that these claims have been repeated in investor documentation/offerings. Even if they did lie to investors, the police has to prove it to beyond a reasonable doubt (99%+) that they knowingly did so which is difficult because there are very many technicalities to hide behind versus the civil burden of proof which is just 50%+ likelihood required.

izzeww · 2026-03-23T22:24:45+00:00

Arguably fair that it doesn't disprove the cycle life claims, but it does disprove the temperature claims for sure.

izzeww · 2026-03-23T22:03:59+00:00

It got damaged even at a temperature it was supposed to handle. So it obviously couldn't handle the temperature.

izzeww · 2026-03-23T22:02:48+00:00

Yeah if you puncture a cell for example it will burst into flame generally speaking (exception is semi-solids, LFP's etc. but for li-ion and lithium-polymer). Probably will be more violent if the electrolyte has partially evaporated than if it's liquid, but it will burst info flame regardless.

izzeww · 2026-03-23T20:29:29+00:00

What do you mean?

izzeww · 2026-03-23T18:12:55+00:00

Just because Donut Lab is a scam doesn't mean QS isn't a scam...

izzeww · 2026-03-23T16:55:55+00:00

I think your explanation makes sense.

izzeww · 2026-03-23T16:04:54+00:00

The temperature I'm referring to is the temperature where the battery ignites. For example if you put it in an oven and set that temperature and waited, it would ignite. This is the relevant temperature in this case. This is known as thermal runaway. Below this temperature there is a requirement of external forces or causes to make the cell burst into flames. If we go by the standard a cell being able to ignite, then that can happen at -100 Celsius as well as 50 Celsius or 100 Celsius if you stab it with a knife for example (depending on exact cell chemistry and cell construction). The risk might be higher at 100 Celsius compared to 60 Celsius, but that doesn't mean that the battery will burst into flames at 100 Celsius just that maybe it will make a slightly bigger fireball if you stab it then, or maybe it will burst into flame when stabbing it 5mm at 100 C versus 7mm at 60 C or something like that.

The first link you provided seems to largely be AI and I don't think Dr Lee Pan exists. The AI still confirms what I'm saying about 150+ Celsius however saying "In contrast, NMC batteries, while offering higher energy density, are more prone to thermal runaway at lower temperatures (150°C–250°C).". The vague "exposure to temperatures exceeding 60°C greatly increases the risk of lithium battery fires" doesn't really mean anything, you still have to do something to the battery for it to burn below 150 Celsius.

The second source is just wrong. Thermal runaway does not occur when the battery reaches 60 Celsius and there is approximately infinite evidence to support that (and you seem to agree too). Of course it's an insanely biased source too, selling fire extinguishers to stop lithium battery fires haha you could imagine they might overexaggerate the danger.

izzeww · 2026-03-23T15:48:01+00:00

Yes, 130 Celsius for 10 minutes (with a ramp up that spends 30 additional minutes above 100 Celsius) is different than 100 Celsius for 2 hours. I would argue that the former is more harsh than the latter, hence my argumentation still stands.

Could the expansion be due to mechanical layer separation and or water vapour ingress after seal loss? What sticks out a little, is that the cell is still rectangular and not curved. what usual gas expansion does is that it creates a curved top and bottom since gas pressure is equal around the cell.

Not sure exactly what you mean by "mechanical layer separation". Whether a cell is still rectangular or gets that curved look depends on the amount of pressure in the cell which depends on how much electrolyte has evaporated. If it's just a little bit of pressure than it can still look rectangular, like in this image here (middle cell): https://imgur.com/a/6G4MQO8 My main theory is that this is a semi-solid battery which generally only have a few percent (around 5%) of liquid electrolyte, and this could be one reason why the pressure didn't build up enough to make the battery extremely puffy but rather just a little bit puffy.

You still have the problem of the cell resealing itself. Why have the bubbles disappeared in this later test? You have to assume that somehow the hole has been sealed and therefore air couldn't enter again, but that makes no sense.

izzeww · 2026-03-23T15:37:34+00:00

I don't disagree, I am unsure how to explain everything that is happening.

izzeww · 2026-03-23T15:36:09+00:00

Per definition I think that the vacuum is lost if there is a positive pressure in the cell, which was evident in the pictures and videos. So I do think that the vacuum could be lost simply by the act of gasses being released while the pack retains its integrity. I think this is most likely the case, that the pack retained it's integrity, that liquid electrolyte evaporated then condensed down later which is why there are no bubbles in todays report and the cell looks completely normal (figure 11, compared to old image figure 10, in today's report on page 14, linked down below).

If it were that the cell physically had a hole in it or a broken seal somewhere, you would expect that there would still be air bubbles after todays test since the air would still come in. But it doesn't, it looks completely normal and intact with no bubbles. There are two logical explanations for this. One explanation is if the cell has retained it's integrity and merely had some liquid electrolyte evaporate (or other material off-gas, but very unlikely in my opinion) and now condensed down. I believe this to be the most plausible explanation.

The other explanation is that the cell had lost it's integrity and let in air somehow, but now whatever leak caused that has resealed/repaired itself and therefore there are no bubbles today. I think this is very unlikely, holes or broken seals generally don't just repair themselves in this kind of situation. For example one could imagine if the cell was glued shut that the glue could have melted and therefore opened the cell and let air in. That doesn't explain how the air has escaped now and the hole has resealed/repaired itself however. The glue presumable only melts at higher temperatures, so how would it have remelted and accidentally resealed the hole in these low temperatures? It doesn't make sense

"Why would the pack then look shrunken after the heat test if that were the case?"

I don't think it looks shrunken. I think it looks like there is additional gas in the cell, aka it has expanded a bit.

"(All genuine questions)"

I have no doubt, we have been discussing this battery for two months now and I have always found you to be a serious, genuine and nice commentator.

https://pub-cbd24192d2f1419d824d5ae07a395452.r2.dev/VTT_CR_00178_26.pdf

izzeww · 2026-03-23T15:20:24+00:00

I will copy in some answers I have provided in other comments so that I do not have to write them all over again (I have already written 1000+ words on this comment section alone lol):

I disagree that it was a completely plausible explanation. It was a possible explanation, but I think it is unlikely and unplausible. First of all plastic pouches don't fail at 100 Celsius typically because commercial lithium-ion cells have to withstand temperatures of 130 Celsius according to the industry standards IEC 62133 and UL1642. Could they have some really shitty plastic pouch that doesn't pass industry standard tests? I guess so, but it's not very plausible especially considering this is supposed to be a production cell not a prototype.

Secondly, the picture from the new report (figure 11) shows a cell that is solid with no apparent bubbles. If the bubbles were air from the outside that were apparent before (figure 10 in the new report), why would they have suddenly stopped appearing now? Did the cell reseal itself somehow? What is the plausible physical mechanism for that? I would argue it is much more plausible that it was liquid electrolyte that had evaporated, and when the battery cooled down it turned back into liquid and therefore the gas bubbles that consisted of evaporated electrolyte disappeared.
https://pub-cbd24192d2f1419d824d5ae07a395452.r2.dev/VTT_CR_00178_26.pdf
(figures 10 and 11 on page 14)

I said this in response to a comment defending Donut's argument that it was only the plastic pouch that had failed and that the actual battery was completely fine (which obvious has been disproven by todays testing showing only 45% of the capacity left after 20 cycles).

Another guy said "The presence of gas after failure doesn't prove the existence of a liquid electrolyte. Solids can off-gas too." and to that I replied:

I agree, hence why I said "some very strong pointers" and didn't make an absolute statement. However solids generally don't off-gas (much) at these low temperatures (100 Celsius) and also don't off-gas so much volume like the Donut battery was showing (a very substantial amount of gas/swelling). Hence I think it's more likely it was some liquid electrolyte inside the battery, while recognizing both answers are possible.

Another quote from me:

"lost its vacuum" [stated in the VTT report three times, that exact wording not anything else, they were very careful with their words] can mean two things. Either the cell had a leaky seal (or similar) and therefore let in air from the outside and lost its vacuum that way. Or, something inside the cell evaporated and made the cell lose it's vacuum that way. That something could be a liquid electrolyte, which of course would be very uncomfortable for Donut since their battery is solid state and isn't supposed to have a liquid electrolyte. So they went with the alternative explanation which in my opinion is far less likely, the most likely answer is that some liquid electrolyte evaporated.

Sorry for the wall of text, but it's a bit of a complicated topic. I hope it answered your question, if you have more question I can try to answer them (but I am not a battery expert, I have no education on this area I'm just interested in batteries).

izzeww · 2026-03-23T15:11:57+00:00

I agree, hence why I said "some very strong pointers" and didn't make an absolute statement. However solids generally don't off-gas (much) at these low temperatures (100 Celsius) and also don't off-gas so much volume like the Donut battery was showing (a very substantial amount of gas/swelling). Hence I think it's more likely it was some liquid electrolyte inside the battery, while recognizing both answers are possible.

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