During my travels, I have come to learn that some products used at home or at work can be dangerous when transported in an aircraft. Temperature and pressure variations can cause some items to leak, generate toxic fumes, or start a fire.
Lithium and Lithium Ion batteries are such items that may catch fire when not handled properly. First, you should not use aircraft power ports to charge these batteries. When packing, place spare lithium batteries in carry on baggage's, not in checked baggage. See battery size limitations at safetravel.dot.gov. It is preferable that you use the original packaging to store spares. If the original packaging is not available, store each one in a separate plastic bag or use electrical tape on terminals to prevent the batteries from making contact with metal objects.