I feel like you don't know what you're talking about. LiFePo4 is SAFER than LiIon, but with a lot less energy density. It's not widely available in eBike battery packs. I believe its energy density is between LiIon and NiMH.

When I was heavy into R/C airplanes, LiIon was considered too heavy and weak; we used pouch-type LiPo (lithium ion polymer) which is even MORE sensitive. I'll be surprised if that segment hasn't moved onto super caps soon.