3 ms·
It definitely isn’t the same. The square packing in the first picture uses pi/4 ~ 79% of the space; the second uses pi/(2*sqrt(3)) ~ 91% of the space. They don
by Armisael16 5y ago
It definitely isn’t the same. The square packing in the first picture uses pi/4 ~ 79% of the space; the second uses pi/(2*sqrt(3)) ~ 91% of the space.
They don’t bother with smaller secondary batteries because the extra manufacturing cost and operational complexity isn’t worth it for a 5%-10% bump in volumetric energy density.
- cma 5y agoI didn't mean to say the two packings were the same. 90% is better than I thought circle packing was though, I've mostly seen multi-scale packing used in thermal pastes and stuff and it is probably a bigger difference in 3d sphere packing.
- hinkley 5y agoDidn’t someone prove about 15 years ago that there’s an oval shape that packs tighter still? Given the hollow core that could probably be done, but cylinders are probably easier for the assembly line to handle. So then it comes down to whether that space is being utilized (for cooling, or weight per cubic inch of the support structure).
- cma 5y agoI think there are a couple companies with hollow designs for improving surface area for cooling, or at least patents around it.