Also, "lipo" batteries are actually the least safe configurations for liion. LiFePo and LiTi are inherently safer, but liion pouch cells are probably the worst even amongst other batteries of the same chemistry. A regular 18650 is very hard to puncture or deform, does not swell and has built in vent ports on the top- a li-po usually doesn't. So they have very little structural integrity, can be easy to puncture (which sometimes lead to internal shorting), have a hard time venting gases when they overheat, and need to be kept compressed to avoid swelling.
The reason they are still used is because of the huge weight savings that comes with not having a heavy steel casing and because they are a lot more modular. That also means they can be made larger and push a much higher amperage. At the very high end you can go up to 200-300 amps per cell vs 30-35 for high current 18650s.
