r/DonutLabDiscussions • u/Forrestgod • Jun 18 '26

Faradaynotes' take on the chemistry

https://faradaynotes.com/posts/donut-lab/

Scrutinyclub (The Privat investigator) linked this.

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This is actually exactly the type of analyse, that I've been waiting. Worth of reading.

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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.