I just found this while looking for a AW IMR battery and remembered this thread, so here is a copy and paste along with the link. I will be using what ProVape recommends, the AW IMR. Hope this answers your question.
There are 3 categories of rechargeable lithium cells:
Red cell, safe/unprotected (IMR - available from Oveready)
Black cell, unsafe/protected (LiCo with PCB - available from Oveready)
Blue cell, unsafe/unprotected (LiCo without PCB - not available from Oveready)
The 2nd type are popular because they offer the most capacity while being safer to use than type 3. But PCBs use electronics which can break under extreme conditions and like a circuit breaker in your home, PCBs can turn off your cell when you least expect it - sometimes permanetly.
AW IMR 18490 (18500) Rechargeable Battery - Batteries & Chargers - OVEREADY Flashlights/Torches - Control The Dark