I don't know if the rule still applies, but in 2008 they banned airplane passengers from carrying spare lithium ion batteries in checked luggage. But you know, jet fuel also packs a lot of energy.
http://safetravel.dot.gov/whats_new_batteries.html FWIW, the new Airbus planes also use lithium ion batteries.
AFAIK, that rule is still in effect.
These incidents have been covered extensively here (The Seattle environs), and they have not ever reported that the rule had been changed.
No lithium ion batteries in luggage.