I had a 14500 blow up in a completely normal everyday charging situation. I still use li-ion cells, but do things significantly different since that incident.
I’m sure that you have read the FBI report:
The NASA report, although very dry, gives some ways to make em blow (and there fore to prevent ’em from blowing):
I now treat multi-cell lights with real caution; charge my batts outside or in a closed room to contain that black crap in case another one goes off, etc. I don’t generally use Cr123 primary or rechargeables, except in my Trustfire mini.
The biggest change, I think, is that my Chinese battery days are over. I use all brand-name bats that can’t be fake because 99% of them are pack pulls. When I use protected cells, they come from reputable sellers like kumabear.
Even before the explosion, I would never strap two 18650s to my head, but other people do without much concern.
I prefer to keep my li-ion batteries next to my genitals 
……Which if you think about it, is where a flashlight spends a good amount of time when walking … If not directly next to that region, my light end-cap/clickie (the part that would blow off like a bullet in a battery incident) spends a LOT of time aimed at that general area. :–0