Jay Whitacre presentation about the inner workings of a LiFePO4 battery cell
- Thread starter BjornM
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Wow - that looks like a very old video, a lot of things he talks about have proven over time to be incorrect.
It was disappointing that he didn’t expand on the SEI formation of the A123 cells, seemed like he wasn’t privvy to their method.
Still some good basic information though, took me back to when i first started looking at LiFePO4 cells in 2010.
It was disappointing that he didn’t expand on the SEI formation of the A123 cells, seemed like he wasn’t privvy to their method.
Still some good basic information though, took me back to when i first started looking at LiFePO4 cells in 2010.
OffGridForGood
Catch, make or grow everything you can.
Is there a better - updated video available that explains the cells better?
I imagine my eyes would glaze over just as well with a new 4k video as they did on the low rez older one posted above
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Not that I know of. I get my information directly from cell designers / manufacturers. Over the years I’ve seen too many people follow information from this type of video and prematurely destroy cells. Unfortunately often tens of thousands of people end up circle jerking over information presented in this way making it very difficult to correct.
Examples from this video are:
- cell over / under voltage limits. “You won’t harm a cell unless you go over 4V or under 1V”
- cell temperatures. “You won’t harm a cell even if you charge it at -20°C, and up to 60°C”
- Matched cells in series don’t need BMS cell level intervention (admittedly very few manufacturers were using cell level balancing in EV’s at that time, most do now)
He did have a grasp on the importance of electrolyte and build up of SEI, and briefly touched on the crystal formation of the LiFePO4 and graphite layers. If you talk direction to a cell designer, these things, along with the initial charge SEI formation are the critical factors to cell lifespan.
I doubt you’ll find someone that actually knows about these details that is willing to publish their work - it is pretty closely guarded. (as he found out even back then when asking A123 for their SEI formation charge routine).
OffGridForGood
Catch, make or grow everything you can.
I feel a majority of the members on the forum would know all three of these statements are 'patently wrong' however, in the absence of a more up to date video, most of the general public would not know this.
Point being there are plenty of current videos and forum information that is also ‘patently wrong’, yet widely circulated as truth - even on this forum. When this happens, it is very difficult to correct as it was with the information in that video a decade ago.
What makes it worse, especially with LiFePO4 in a low C environment, is that the result of following misinformation may take many years to manifest. I know of several practical studies that began in 2007 that are still ongoing and at this stage inconclusive.
The fact that the formation of lithium ions from the LiFePO4 lattice is literally a different reaction at low C rates makes some aspects of lifespan analysis difficult.
OffGridForGood
Catch, make or grow everything you can.
Where we see errors and have documentation to combat it, we each should take the time to correct patently wrong information and bring the forum to a higher level of understanding.
My earlier comment that the three examples would all be recognized by forum members as patently wrong is based in the evidence I have seen posted on the forum, not just opinions or widely held and circulated beliefs. For example the affects of charging and discharging LiFePO4 at high temperatures was discussed and members provided links to credable research papers on the topic illustrating the results of cycling at low, moderate high and very high temperatures. in great detail. We could all read the research papers for ourselves and draw our own conclusions (I will be sure to keep my ESS in mild temp range). The state of the art is constantly changing, the best we can do is pay attention and try to keep up on the best information available while speaking up on misinformation where we have credable sources to refute it.
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Yes, modern society’s greatest challenge is to determine which source of information is credible.
The views in the video posted were also accompanied by research papers at the time confirming their accuracy.
This years credible information is next year’s falsehood.
Good luck!
The views in the video posted were also accompanied by research papers at the time confirming their accuracy.
This years credible information is next year’s falsehood.
Good luck!
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