I'd best get my arse into gear. There are a lot of misconceptions about batteries and that ain't not safe.
For where you are now PV and until you become more conversant with what is probably the most involved and crucial subject in vaping, i.e. batteries, I think rather than get bogged down in technical details, albeit necessary ones, it might be best if you progress with bite sized pieces for now.
Basically, there are three types of vaping 1800 series batteries. ICR, which stands for Lithium-ion Cobalt Rechargeable. IMR, which stands for Lithium-ion Manganese Rechargeable and a fairly recent innovation from Panasonic, which although technically is of an ICR structure, they are in fact a combination of the two formats making them a hybrid if you like.
Now before Panasonic, you more or less had to choose between a market driven longer amp/hour ICR which is known to be of a volatile composition or a less volatile but safer, IMR battery. Safety was winning the day at long last.
An IMR battery will:
charge faster
discharge at a higher current
be safer
deliver higher amounts of power to the source,
but have lower overall capacity
Than an ICR battery.
However, the new Panasonic hybrids, using a mix of both chemistries (so I understand), will meet just about all vaping needs. As a for instance, take the Panasonic CGR18650CH. That has a Constant Current discharge of 10Amps which equates to nigh on 40 watts and if anyone vapes at anything like approaching that figure, they will be holding their mod between top quality oven mitts and using a welder's mask for face protection. If you are thinking of sub-ohm vaping PV then I would advise giving the CGR's serious consideration. Failing that stick with IMR's.