It isn't just a matter of just optimal-packing the material, you have to figure out the thermal runaway problem. That's the big argument between prismatic vs cy

It isn't just a matter of just optimal-packing the material, you have to figure out the thermal runaway problem. That's the big argument between prismatic vs cylindrical cells, anyway. Prisms do a good job of filling a block of space but they don't provide nearly the structural integrity to contain, isolate, and direct the venting of a misbehaving cell.