Wasn't there a problem a few years ago with iPods and batteries overheating?
Li-ion/Lipo packs do not have anything in them to prevent this, unless someone adds such circuitry. That can be part of the pack or part of the device using them.
I had run lipo (same battery in cell phones and readers, different from the li-ion in laptops) in RC modeling for a number of years. Failures of usch batteries come from several causes:
Too high if discharge rate - short one of these and it gets nasty.
Charging after being overly discharged - if the battery is discharged to too low of a voltage, when trying to charge it, it can have issues.
Overcharging - these cells are limited to 4.2 volts per cell MAX voltage. Higher voltage applied to a cell will cause it to fail.
Damage - if a cell is damaged it can fail or it might not fail until the next time being charged.
Leaving the cell fully charged for a period of time will cause a loss of capacity, but not a violent failure.
The cells contain an amount of flammable solvent, so whenthey over heat, and the envelope ruptures, the solvent can catch fire. The industry calls such failrues as "venting with flame."
