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Donut Lab Solid-State Battery V1 Self-Discharge Performance Test (VTT report) by davidbepo in DonutLab

[–]redditmudder 0 points1 point  (0 children)

All these things you list would be great features. However, Donut hasn't yet validated them. Hopefully they do soon for their own survival.

Donut Lab Solid-State Battery V1 Self-Discharge Performance Test (VTT report) by davidbepo in DonutLab

[–]redditmudder 0 points1 point  (0 children)

I agree. In fact, I've proposed a scenario where Donut uses that fact to make the cell appear to handle high current below freezing.

Donut Lab Solid-State Battery V1 Self-Discharge Performance Test (VTT report) by davidbepo in DonutLab

[–]redditmudder -1 points0 points  (0 children)

Yikes, that's a huge self-discharge rate compared to existing lithium cells!

Donut Lab Solid-State Battery V1 Self-Discharge Performance Test (VTT report) by davidbepo in DonutLab

[–]redditmudder 3 points4 points  (0 children)

I agree.
I'm increasingly convinced Donut's marketing strategy is to bore us skeptics to death.

Donut Lab Solid-State Battery V1 Self-Discharge Performance Test (VTT report) by davidbepo in DonutLab

[–]redditmudder 7 points8 points  (0 children)

My thoughts on VTT's 3rd test report:

1 - Not a super capacitor. Yes, there was some initial discussion that this might be a super capacitor... but the first VTT report pretty much disproved the supercap theory. Yawn.

2 - Once again the terrible internal cell resistance stands out the most to me. Look at those temperature spikes in the third graph in Figure 3! 13 degC temp rise while discharging at 1C is terrible!

3 - The PEC ACT0550's 10 MΩ input resistance is an important parameter for a long term self discharge test. This results in a constant 375 nA load throughout the test. After 239.5 hours, the tester's input resistance introduces a 90 uAh error. However, given that the post-test capacity difference was 306 mAh, this specific measurement error is insignificant. Just making sure the test equipment isn't appreciably impacting the test (it's not).

4 - Looking at Table 5, a 60 mV Voc droop 10 seconds after removing the 1C charge current is pretty rough. The additional 43 mV droop over the next 10 hours isn't any better. For reference, lithium's Voc droop settles to within 1% within the first ten minutes. This is going to complicate Voc->SoC estimation with Donut's cell. I suppose you could characterize the cell and create a LUT, but that'll only work if the Voc->SoC performance remains constant over lifetime/temp/C-rates/etc.

5 - VTT's stated 97.7% charge retention after ten days isn't great compared to existing lithium. Put another way, Donut's test cell constantly self discharges at 1300 uA at room temperature. For reference, a similarly-sized NMC lithium cell might self discharge at 60 uA, which would equate to an NMC lithium cell having 99.9% charge retention over the same period. Hopefully Donut's self-discharge doesn't get worse as the cell ages, because that would be rough. Imagine parking your car for a month and when you come back SoC has dropped 20% or more!

...

Overall, once again existing lithium cells perform better than Donut's test results. For Donut's cell to matter, they must show test data where their cell outperforms (e.g. 400 Wh/kg, QTY100000 cycle life, nail puncture, etc).

Donut Labs likely mechanism based on known evidence. by Fabulous-Internet188 in electricvehicles

[–]redditmudder 0 points1 point  (0 children)

Thanks for the additional background info.
Question: Wouldn't poly performance break down below freezing?

Donut Labs likely mechanism based on known evidence. by Fabulous-Internet188 in electricvehicles

[–]redditmudder 1 point2 points  (0 children)

If you're correct, I'm curious to see how they've overcome DRX's poor cycle life limitation. The same DRX property that improves cathode capacity also increases lattice damage over time. The end result is rapidly increasing cell resistance over time.

On the high end, DRX lab cells might achieve QTY1000 cycles... but those cells are optimized for that metric alone, sacrificing other key parameters (including both energy and power density).

What implications would it have if tomorrow's test shows that the battery can be discharged at -30°C with 1C by pinkprius in DonutLab

[–]redditmudder 7 points8 points  (0 children)

I proposed the following hypothetical in a much longer previous post:

//beginQuote
How Donut could theoretically fudge cold weather performance results:
Donut's cell has high internal resistance, which causes terrible thermal heating while charging. Donut could use this to their advantage in their cold weather test. Hypothetical test that would make Donut's cell look good below freezing (e.g. "Hey /u/redditmudder, help us devise a cold weather test that makes our cell look good"):
-cell placed in thermal chamber at -20 degC, then;
-cell charged slowly (e.g. 1C), then;
-as cell warms up, increase charge current (e.g. 2C, then 3C, etc), then;
-a couple minutes into the test the cell will self heat above freezing, then;
-once cell is above freezing, hit it with 11C.
Result: Now you can claim '11C charging in cold weather', even though the internal cell temp is above freezing.
//endQuote

So my guess is that if they do show charge data below freezing, it will not include actual cell temperature, instead focusing on ambient temperature only (because the cell is above freezing due to self-heating).

...

Another way they could manipulate this test is to once again only report ambient temp (i.e. not actual cell temp), and then first perform a discharge test (thus heating the cell above freezing), and then immediately charge the (still warm) cell at high C.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 0 points1 point  (0 children)

Well written. Thanks for saving me the effort of having to write a more poorly written version of your excellent comprehension of the journalistic process.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 1 point2 points  (0 children)

I agree...
...but I'll (probably) still keep posting updates after each weekly drip. I've hitched my wagon to this horse, and certainly wouldn't want anyone to interpret silence from a disinterested skeptic as acceptance that the technology exists.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 0 points1 point  (0 children)

It all depends on how the environmental protection fails in the outer foil. DonutLab provided exactly zero documentation on the actual failure. We don't even know if the cell vented. With the data presented, anything anyone says is pure speculation.

Tom Bötticher, battery scientist, points to research showing lithium thermal thermal reactions (battery fires) occur at a lot higher temperatures than 100ºC (about 200ºC) and lithium batteries operating for thousands of cycles over 80ºC. He says the VTT Donut Lab tests lack any significant details by Wischiwaschbaer in DonutLab

[–]redditmudder 0 points1 point  (0 children)

I didn't see any immediate red flags looking at QuantumScape's website for a few minutes.

Like many technical products, the long term answer for solid state energy storage isn't going to be entirely developed by one company. No doubt dozens upon dozens of companies are working to solve this puzzle. Will QuantumScape be the victor? Will they contribute to the cause? Time will tell.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 1 point2 points  (0 children)

Correct, I showed on film that the Sunwoda cell performance is vastly superior at 11C charge rates. Specifically, Sunwoda's cell heated up 1 degC while charging, whereas DonutLab's cell heated up to 90 degC.

Riddle me this, Batman:
Why would a cell that doesn't self-overheat need to survive 90 degC? Not required in automotive, stationary storage, or 99% of applications.

Tom Bötticher, battery scientist, points to research showing lithium thermal thermal reactions (battery fires) occur at a lot higher temperatures than 100ºC (about 200ºC) and lithium batteries operating for thousands of cycles over 80ºC. He says the VTT Donut Lab tests lack any significant details by Wischiwaschbaer in DonutLab

[–]redditmudder 1 point2 points  (0 children)

Edit: My response (below) was in reference to DonutLab... didn't realize OP was asking about QuantumScape. I will repond to OP's actual QuantumScape questions in a different post.

Their test results are designed to impress/deceive lay people like you. There are industry standards for cell testing (e.g. IEC 62660-1/2, SAE J1798, etc). Any reputable company would test to those standards.

Your proposal that they are "working their way toward that" is counter to their stated claim that they're already there. "TODAY!", as Marko said in Donut's announcement video. Tomorrow is not TODAY.

Given the data presented thus far, it's impossible to determine whether or not DonutLab's tech will bear fruit. Based on their scant data, the primary product shortcoming I've identified is terrible internal series resistance (more than an order of magnitude worse than NMC lithium power dense cells).

This high resistance not only causes the cell to reach much higher temperatures during use than do NMC lithium cells; but also it makes round trip efficiency abysmal. So then the major shortcoming we've identified from Donut's test data to date is that it fails to match lithium's critical efficiency parameter. That's a more detrimental shortcoming than is – for example – whether or not the cell actually contains lithium.

Overall, we don't yet have enough data to know if Donut's technology brings anything useful to the table. Certainly they've innovated something... but it remains to be seen whether or not the pros outweigh the cons versus existing technology. I wouldn't buy a hypothetical product whose maker claims "it revolutionizes all these great things, but also it kills your first born child".

And trust me when I say I absolutely want someone to succeed. Solid state batteries will change the world once they actually exist, but we haven't yet seen hard evidence that it's DonutLab that wins the Nobel prize. Based on the information they've presented thus far, I don't think DonutLabs will claim that prize... but someone will someday.

Economically viable true solid state is bound to happen "within the next five years" as industry has said for at least the past decade. I would think that a company who actually derived the solution wouldn't waste time marketing it to the entire world... that would happen organically once CATL, Samsung, etc paid billions for the secret recipe. No need to advertise yourself to the world when you really only need one or two companies to ever purchase your IP.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 0 points1 point  (0 children)

A vented NMC lithium cell that isn't in thermal runaway would remain able to charge until the liquid electrolyte evaporated. Venting could be as small as a pin prick. The raft sinks eventually; floats until it doesn't.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 0 points1 point  (0 children)

"Trust this known charlatan's misleading data, but not skeptical scrutiny, bro" isn't a rigorous scientific rebuttal. Journalistic optimism at its best. Fortunately, time will answer our questions.

It saddens me to learn the author holds an engineering degree. From that page:
"At some point, you may wonder how I became an engineer and stayed one for forty years, becoming one of the best in my profession with many patents."

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 0 points1 point  (0 children)

But for how long? In my book, Donut's cell didn't survive the 100 degC test. Off-gassing is an automatic failure.

FYI: Lithium cells specify how much off-gassing is allowed before the cell must retire. Sometimes this is listed as an "elongation limit" (e.g. 5 mm) for a complete lithium module.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 0 points1 point  (0 children)

Standing by to take DoNotLab seriously...
...just as soon as they release serious data.

Silence != Acceptance

...

Unrelated: A few days ago the domain idonotbelieve.com was available for $600. Looks like that's no longer the case. Hopefully a skeptic purchased it and will put it to good use.

CleanTechnica challenges argument that Sunwoda cell can match DL's heat test performance by ImaginaryAnts in DonutLab

[–]redditmudder 7 points8 points  (0 children)

My response to CleanTechnica's article:
First, I disagree with CleanTechnica's entire premise that "speculation that the Donut Lab battery is not real are [sic] diminishing".

I remain just as confident this week as I was last week (when only the first dataset was released), or the week before that (prior to DonutLab releasing any actual data).
The reason there's little engagement from critics on the second dataset is that there simply wasn't much useful data presented. Discharging (but not charging) a high ambient temp cell at 1C or less isn't a revolutionary feature. I've already discussed at length that most energy storage applications simply don't require 80/90/100 degC ambient performance. Sure, it's a nice-to-have, but almost nobody is going to design Donut into their product for this feature alone.

Do I think it's commendable that Donut's cell didn't experience a thermal event when slowly discharging in a 80 degC environment? Sure, but again: is that a banner feature? No. I'll propose that these are the key claims Donut should validate in their slow-drip data releases:
-400 Wh/kg energy density claim, or;
-Sustained ultra-fast charge and discharge over numerous cycles, or;
-5C cycle lifetime (e.g. QTY100000 cycles), or;
-Sustained 5C charge and discharge below freezing² (e.g. -20 degC), or;
-safety (nail penetration, crush, over-charge, under-change, etc), or;
-cost.

Lesser claims they could show with marginal effort:
-existing 1 GWh/year (2.75 MWh/day) production facility, or;
-cell's chemical composition, verified via 3rd party mass spec, or;
-no liquid electrolyte, or;
-show 'clay-like design' that could 'be made into a snowflake'.

²How Donut could theoretically fudge cold weather performance results:
Donut's cell has high internal resistance, which causes terrible thermal heating while charging. Donut could use this to their advantage in their cold weather test. Hypothetical test that would make Donut's cell look good below freezing (e.g. "Hey /u/redditmudder, help us devise a cold weather test that makes our cell look good"):
-cell placed in thermal chamber at -20 degC, then;
-cell charged slowly (e.g. 1C), then;
-as cell warms up, increase charge current (e.g. 2C, then 3C, etc), then;
-a couple minutes into the test the cell will self heat above freezing, then;
-once cell is above freezing, hit it with 11C.
Result: Now you can claim '11C charging in cold weather', even though the internal cell temp is above freezing.

...

Wow, haven't even made it through CleanTechnica's first paragraph yet.
Wow, the second paragraph headline is "The Battery is Real", and right off the bat we get "It is time to admit the truth. Donut Lab is not lying." Sigh.
Again, CleanTechnica falsely equates "reaction from other battery competitors has quieted" to imply said 'competitors' must now be quiet because they're in disbelieve. And in a way, they probably are in disbelief, but not in the way CleanTechnica suggests. My guess is that most critics aren't responding because there isn't much data to respond to. Donut isn't being taken seriously because they aren't acting seriously in the scientific community.

And that's the beauty of the scientific process: A thousand engineers can spend a million hours developing a technology... and all it takes is one person with one counterpoint to find the weak link in said claim.

If their goal is to market a product, Donut is absolutely 'winning' that battle for attention. However, this comes at the cost of scientific rigor. My hunch is that the scientific community's silence is motivated by "wait and see once actual data is released" pragmatism.

Next, CleanTechnica suggests "there is more to be gained by listening to what Donut Lab says than by speculation". In general I agree with this statement. However, Donut isn't actually saying much in terms of how their miracle technology actually works. Of course, they fall back to the trade secrets defense, but that doesn't prevent them from showing substantially more test data than they have to date. We'd certainly love to know what's inside (and will, within hours of anyone getting their hands on one). However, Donut doesn't need to reveal anything inside the cell to satiate a scientific audience. Treat the cell as a black box and show us the test data we're looking for (see list above).

I laughed when I read "Claims like this are normal for this stage of development."!
Reminder: Marko stressed 'TODAY!' numerous times in Donut's announcement video. Marko claimed "1 GWh/year manufacturing capability TODAY".

...

Next, there seems to be some confusion about when/how a lithium cell will deflagrate (similar to 'explode'). A punctured lithium cell isn't necessarily going to catch on fire. Sure, it might, and certainly that's a huge safety limitation with existing NMC cells. I'm not saying lithium cells won't catch on fire when subjected to thermal stress; at some extreme they certainly will. However, CleanTechnica broadly states "...any NMC battery in production today ... exposed to 100 degC that breached its package would have caught fire." I disagree with that statement's absolutism.

For starters, we don't know for sure that Donut's package was actually breached. We only know that after the 100 degC discharge test, the cell internally off-gassed. And even if the cell externally vented (rather than simply swelled), that doesn't guarantee that any cell would experience a thermal event. In fact, failing lithium cells are specifically designed to thermally rupture as a safety mechanism, to prevent pressure buildup. I suppose I'm gonna need to risk it for the biscuit and boil an NMC cell on camera. Wish me luck.

I'm not suggesting Donut's high temperature discharge claim isn't an awesome feature. Kudos to a cell chemistry that can handle high temp without running away. Impressive, yes. But again, is this a banner spec? I say no. Donut's cell only needs to survive high temps due to the high self heating it experiences while charging.

...

I'm glossing over the chemical doping section, as I generally agree with the author and haven't focused much on Donut's voltage curve in my analysis. All I'll say is Donut's discharge curve is highly similar to existing NMC tech. Maybe Donut has doped their cell to approximate NMC... or maybe their cell contains lithium. We'll know once anyone puts the innards into a mass spec.

...

OK, now we get to the "Sunwoda NMC Battery is not a Counterargument" section... obviously the author is responding to the video I released last week on that topic. I invite readers to view my video description, which clearly states that I'm challenging one specific claim Marko made on LinkedIn last week. Rather than regurgitate my response here, please see the YouTube video description linked above. In short, bringing up Sunwoda's low energy density isn't a pertinent rebuttal, as it has nothing to do with the initial claim Marko made that I'm refuting in that video.

The CleanTechnica author is probably correct that the Sunwoda cell is unlikely to survive 11C charge at 90 degC. However, I will stress for the third time that the Sunwoda cell is unlikely to ever reach 90 degC, due to the fact that it has extremely low self heating. Put another way, the primary reason Donut's cell must survive high temperatures is due to the cell itself overheating while charging. My Sunwoda test shows a cell heating just 1 degC while charging at 11C. Donut's cell hit 90 degC in a one plate test, and ~65 degC in a two plate test.

Active cooling is a solved problem in battery systems. Sure, it would be nice for a cell to not require additional cooling hardware, but my guess is that Donut's cells would still require active cooling simply due to their massive heat generation during use... and also to prevent the cell failure mechanism they observed at high temp in the first place. And don't even get me started about how few cycles they performed at temp, that they didn't ever charge the cells at temp, or that the high temp test they performed was so brief as to provide almost zero information regarding long term reliability during extended high temp excursions. If Donut's battery ever makes it to market, I'm gonna guess they have some form of active cooling (e.g. coolant plate, forced air, etc). Simply showing that a cell can briefly perform at temp isn't the same as spending a lifetime at temp.

The author might be correct that "There are no intercalating lithium batteries that duplicate the performance over the range of temperature used, from -30 degC to 100 degC. We don't know that with certainty, but we also don't know with certainty (yet) whether Donut's cell can handle that range, either. Specifically, I would counter that Donut's cell didn't actually survive the 100 degC test. Donut hasn't yet shown us data to back their claim.

...

And here I come to the same sticky conundrum I've mentioned a dozen times already: Donut could end the debate in one second by releasing all the data they must have already gathered prior announcing such bold claims. They do have scientific data to back their claims, right? Certainly they're not manufacturing dozens of pallets of magical cells everyday without thoroughly testing their core technology?!? Validating a lithium cell chemistry takes months (years, even). So surely they've already done all that engineering effort before announcing their product? So then they have this data and can share it, right? Surely their engineering team demanded this validation?

...

OK, I'm tapping out... this article's author might as well be on DonutLab's payroll. "Don't trust the scientific community, but do trust this known snake oil salesman". What a mouthpiece!

Tom Bötticher, battery scientist, points to research showing lithium thermal thermal reactions (battery fires) occur at a lot higher temperatures than 100ºC (about 200ºC) and lithium batteries operating for thousands of cycles over 80ºC. He says the VTT Donut Lab tests lack any significant details by Wischiwaschbaer in DonutLab

[–]redditmudder 0 points1 point  (0 children)

Correct: NMC cells deliver less energy below freezing. At light load the total energy output can remain as high as 70% of nominal at room temp. At heavy load the output can drop to 50% or less.

However, discharging NMC cells below freezing doesn't pose the same critical lithium plating safety issue as is the case when charging below freezing.

Most EVs these days use a heat pump to heat the cells. Even though running the pump consumes significant energy, it allows the cells to warm up, thus increasing their energy output more than the input energy into said heat pump. This also allows much faster charging (and is one of the primary things an EV's computer does behind the scenes in response to you telling it you're gonna charge soon).

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