This from FAA:

FAA ON LITHIUM BATTERIES
The FAA Friday released a Safety Alert to address "risks in transporting
lithium metal batteries in cargo by aircraft," noting that UPS Flight
006, a 747 that crashed on Sept. 3, was carrying large quantities of
lithium batteries. Fire was reported on the UPS flight but the FAA notes
that a cause of the crash has not yet been determined. The crash
destroyed the aircraft and killed the crew. The FAA has found that
lithium metal batteries are not only "highly flammable and capable of
ignition" but also possess destructive explosive potential. The agency
says Halon 1301, the fire suppression agent found in Class C cargo
holds, "is ineffective in controlling a lithium metal cell fire" and
lithium metal battery explosions can lead to "rapid fire spread" in
cargo compartments. Lithium-ion batteries are somewhat different. They
can exhibit the same thermal runaway as lithium metal batteries, but the
FAA says Halon 1301 is capable of suppressing lithium-ion battery fires.
The FAA's alert offers recommendations that are limited to batteries
flown in cargo holds and do not apply to batteries carried by passengers
or crew. The FAA is considering courses for further action.