paper on dendrites and current pulsing

EGOksy said:
9 mA cm-2 .. how much does it calculate to for 18650 ...
Click to expand...

Should be easy to calculate if you find the area of the "jelly roll" inside the 18650. Couldn't find this info from an hour or so of searching however.
 
Clive is awesome! :D
 
SecondHandPower said:
Found a new study on fusing dendrites with high current pulses in experimental chemistries....
Click to expand...
That first post was a bit shorterthan I wanted to post, butI was boarding a plane.

I mentioned chemistry because the paper sounded like it was research on a Lithium chemistry with sulfur.

Code: 
"We show that repeated doses of high-current-density healing treatment enables the safe cycling of Li-sulfur batteries with high coulombic efficiency," the researchers noted...

To be clear,the 18650 cells we are processing have different ingredients than they are using in the lab, so the dendrite paperis not how to "heal" a typical 18650 cell.

I like the optical photos of the "jelly roll" in the video by Clive. (and the points cautioning against high currents for extended periods). Kind of scary to see those conductive shapes growing inside.

Here is a page with some pictures of some cells Ihave seen from laptop packs, grouped by chemistry with a short description of common ones.
https://batterybro.com/blogs/18650-.../18880255-battery-chemistry-finally-explained

Cheers
 
"Researchers first demonstrated this smoothening (healing) of the dendrites in a lithium-lithium symmetrical cell. They then showed the process with the same results in a proof-of-concept demonstration using a lithium-sulfur battery."
https://www.nanowerk.com/nanotechnology-news/newsid=49823.php

They tried it on diffrent cells, not just sulfur..

Reverse discharging is obviously going to destroy any cell due to the electron potentials and electro chemistry.

Reading the original article (I could not get hold of the actual research paper with the rest of the detail in) the effect of high current charging is part of the reason some electric vehicles see a difference in cycle life. Fast chargin above 1C and in some instances well obove 1C is closer to the 3-5C charge rates they seem to be performing with the sulfur cells. Dendrite electron potentials and chemistry should show some form of response in other cells.

For a typical powerwall with 100p packs and 2Ah cells, you may need to push close to 1000A through the pack. The article did not state how long the charge pulses were and the thought of pushing 1000A through any of the DIY packs I have seen would be impossible due to the small cell fuse wiring.

What would be interesting is to take say 5 or 10 cells that were originally around 2-3Ah and the current state is 1Ah and discharge them to around 3.3V and then give them a 2-5 minute charge at 10A, pause for it to cool and the then perform a couple of full cycle capacity tests...
This could be a way to partly recover some time of cell failures...
 
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