LiOn is pretty reactive, and if you do things like put a overly discharged battery in series with a fully charged battery, they get pretty hot and vent a lot of gas and can flame on. On BudgetLight forums there are lots of warnings to just be nice to the batteries and take some precautions when charging. Over discharge, overcharge causes problems. Shorting them out really causes problems. High capacity and low internal resistance give them excellent high current capability.
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Disclaimer: 99% of what I know about cycling I learned on BF. That would make, ummm, 1% experience. And a lot of posts.