Thermal runaway is no fucking joke friends! I vape, and until last summer used one if those big mods with removable lithium batteries. I was not safe about it, and carried spare batteries in my pocket.
One day, almost exactly a year ago, I won the stupid games stupid prize and my leg exploded like a road flare was in my pocket. I grabbed at it instinctively, torched my hand and ended up stripping off my pants in my restaurants kitchen and having servers pour water over my hand and thighs while i waited for EMTs.
I was out for about 5 weeks and thankfully didnt require grafts. I got to learn all about burns and how the body can heal, which was neat. The hand was fully functional 10 days after intense second degree burns over 70% of it. The thigh took forever to heal, but fully did.
Anyways, be careful with those things! Any exposure of that lithium to the outside environment and it's a wrap, it burns until the lithium is gone. There is no extinguishing it and its hotter than a welding torch.