Comment by cyberax
14 hours ago
Yep. Prismatic cells have poorer packaging-to-material ratio (circles are optimal). They offer better thermal properties, but thermals are not the main limiting factor anymore.
And the US automakers tried prismatic cells before. Chevy Volt used them in 2012!
Chevy sells EVs with prismatic and pouch cells. I don't recall any they've widely sold that used cylinder cells. Most automakers use prismatic cells on their cars, even non-LFP variants.
How are circles optimal???
Circle packing = 90%
Blade battery packing = 100%
it's not just a basic geometry problem, it's an engineering problem. You need to account for far more details.
With cylindrical cells, you have more leeway in the overall shape of the battery pack and can fill nooks and crannies with them.
It's more complicated. You can't pack the battery at 100% anyway, because you need cooling. Cylindrical cells are also more rigid, so they need less supporting material, or they can even be a part of the support structure itself.