[rkagerer]

TLDR: During a battery's initial "formation" charge, some of the lithium deactivates, forming a squishy, protective layer around the negative electrode, called the solid electrolyte interphase (SEI). Today, manufacturers typically do a slow formation charge, during which about 9% of the lithium is lost to the SEI. It was thought this was needed to form a robust layer. But the researchers found at the higher initial charge currents used in this study, 30% becomes SEI - so you loose some battery capacity (for a given amount of lithium), but wind up with a beefier protective layer on your electrode and better longevity across subsequent charge cycles.

[user_7832]

> so you loose some battery capacity (for a given amount of lithium), but wind up with a beefier protective layer on your electrode and better longevity across subsequent charge cycles

If there's a capacity tradeoff, why not use a slightly modified chemistry (like how LTO is, for example)? Though I guess this article was more about the existence of the phenomenon rather than using it.

[bluSCALE4]

And how long does it take to achieve this 9% layer?

[rkagerer]

From the article it sounds like 10 hours, which is reduced to 20 minutes using the higher current.