There's some perfectly good stuff on Alibaba. However, from afar, it is hard to tell it apart from things posing as quality products.
Those cells are most likely made up of a bunch of 18650s, and of those, there is a wide variety of quality out there.
Best case scenario you get a great deal on a battery. Worst case scenario, it burns your van and home to the ground. Since I really don't like the potential worst case outcome, I'll continue to source my lithium ion batteries from companies with US based engineering resources that imply some level of accountability.
I'm not implying that these or any other specific batteries on Alibaba are bad at this very moment. Just that there's no easy way of knowing how safe a particular item is.
'99 EB ex ENG KSWB news van, low rent 4x4 conversion (mostly fixed by now), home built interior.