longer 10440?

there it is

10440 volume:
= 4.4 x (0.5^2) x pi
= 3.45 cubic cm

Lithium Ion Volumetric Energy Density is 900 to 1900 J/cm³

So a 10440 can contain a max of:
6555 Joules or "watt-seconds"

Convert to watt-hours:
= 6555 / 3600 (sec/hr)
= 1.82 Watt Hours
= 1820 mW Hours

Divide by average discharge voltage:
= 1820 / 3.7
= 492 mAh

So the absolute theoretical MAXIMUM mAh of a lithium ion rechargeable battery is:
492 mAh

Then consider the fact that this calculation fails to subtract the volume of metal making up the casing, contacts, protection circuit (if there is one), and further that it represents the HIGHEST POINT in an energy density range for li-ions that on the low end is less than half the figure used here.

In other words, I would be surprised if a 10440 exceeded 350mAh. And my math may be totally wrong. I just pieced this together out of intrigue, from a bunch of different sources. It was fun. It could be totally incorrect