Lithium Batteries come in two sorts, Lithium Ion (L-ion) and Lithium Polymer (Li-Poly, LiPo). The Lithium Ion batteries can be prone to overheating and exploding if not watched and monitored carefully. But it's usually the fault of improper charging or a lax approach. This is due to their being held in an organic solvent and it is flammable.

LiPoly batteries are in a solid polymer composite. The solid polymer (electrolyte) isn't flammable and aren't as dangerous if mishandled. There is also something to the way the cell is built that makes them more stable but I forget what that is.

I often see the "sky is falling" Lithium comments and think them a bit over the top. It's just like handling nitro fuel htere are safetey precautions to take. Not that I am doing a smack-down on former spad I just though this info pertinant.