The max you could get in an 18650 form factor right now is right around 3000mAh, but good luck actually getting them! It is pretty easy to get legit cells that

The max you could get in an 18650 form factor right now is right around 3000mAh, but good luck actually getting them! It is pretty easy to get legit cells that are around 2600-2800mAh though. The ones that are advertised above that are 100% lies and are generally pretty crappy batteries.