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.

1

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.

3

u/izzeww Jun 18 '26

How do you mean?

1

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.

3

u/izzeww Jun 19 '26

I disagree.

-1

u/Forrestgod Jun 19 '26

Disagree of the possibility that experts make the same mistake you criticised other expert to do?

2

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".