I had an old Li Po pack that was swollen and would not hold a full charge. I wanted to see just what would happen if handled WRONG.
I took them outside on the gravel driveway.
I gently unwrapped the battery pack and then unwound the lithium coated strips from the insulation plastic strips on one cell. Still nothing, looked harmless enough. Then I wadded this lithium strip up into a ball and tossed on the ground. In about 20 seconds a tiny trickle of smoke came from it. Then suddenly it went off with a bright flash and a lot of smoke lasting several seconds similar to a small pile of gun powder that had been ignited.
WOW..now I know.
This was hot enough to ignite almost anything that was close to it. I then drove a nail through the three remaining cells, two of them went up in flames. The third one did nothing. I had found my problem.
You definitely want to handle Li Pos with respect and use all precautions when charging or using these.
Charles