Yes, that is my point about heat in the battery being charged. I’d guess that the improvement being touted involves less heat generation as the current is pushed in, and / or less tendency to go exothermic, but, still, 20x is dumping in a LOT of energy quickly.
This can be seen in high capacity batteries being charged by “quick chargers” (ie., high current chargers) available even a few years ago. The batteries get HOT.
Internal resistance of the cells would need to be much lower too — making for high output capacity without overheating, but, if the thing ever shorts out, oh boy!
I happened to accidentally short out a plain ‘ol Alkaline cell in my pocket the other day: It left a very nice burn mark on my leg...
Ow! Don't DO that!
Sony made some batteries (about 300,000, IIRC) for Apple IBooks and for some Fujistsu and Dell laptops way back in the in the early 2000s that had some defective electronics in them. The Apples merely overheated by rapidly discharging and discolored the cases, but the Fujitsus and the Dells, in a few cases, actually caught fire. Apple recalled 50,000, and the other two makers recalled 250,000, but guess which company got the lion's share of the bad publicity? Yup, Apple. . . and it was reported that it was Apple laptops that caught fire, not the Dells and Fujitsus that actually ignited. LOL!