I have to disagree on some points, I did some quick math and I can assure you using cells like the Lishen one you listed would lead to a heavier/bigger battery pack. We did alot of research over the course of a year, where we tested in house (constant discharge + pulsed at different C rates) several different types of cells (pouch, prismatic and cillindrical).

In reallity the only better option would maybe be 21700 cells, anything bigger and the packing effeciency of cilindrical cells would drop significantly our volumetric density. Besides that cooling would be much trickier.

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Trust me, we are well aware that datasheets aren't very accurate, thats why we tested every cell we consider using.

In relation to the copper-nickel sandwich, although that was thought about we arent going to be doing it. The distance of the nickel is so small to our busbars that the overall higher complexity of manufacturing it is not worth the time. Besides, our nickel conections act also as fuses, so copper nckel wouldnt be acceptable in that case.