MIT Professor: Battery Fix Could Ground 787 Until 2014 - Forbes

In a nutshell, Sadoway thinks that Boeing
needs to monitor the temperature and
cool each of the eight cells of the
787′s lithium-ion battery or switch to an
older battery technology that has a far
better safety record — nickel metal-
hydride (NiMH).
If Boeing opts to substitute NiMH for
lithium-ion, certification could result in
delays of up to a year — effectively
grounding the 787 until 2014

http://www.forbes.com/sites/petercohan/2013/01/27/mit-professor-battery-fix-could-ground-787-until-2014/