Li-Ion kept the dreamliner 787 caged, lot of safety issues have been raised against use of Li-Ion in aviation mobile phones etc, here are some interesting articles on the Lion


http://www.ainonline.com/aviation-news/aviation-international-news/2012-02-01/battery-fires-keeping-li-ion-caged

http://www.wsj.com/articles/boeing-warns-carriers-about-flying-bulk-shipments-of-lithium-batteries-1437256427?mod=e2fb

http://www.neowin.net/news/uk-pilots-warn-putting-devices-with-lithium-batteries-in-hold-baggage-is-aircraft-fire-risk