I don’t think the lithium-ion battery is a smart move. There are known issues [battery fires] with them in laptop computers, the Volt and, now, on the Boeing 787. The 787 has had several battery fires and the fleet has been grounded until the reason is found. I’m not an engineer, but I know trouble when I see it.
The A123 type is safe or as safe as any battery. The Lithium Cobalt Dioxide (LiCoO2) chemistry in the Dreamliner, however, is much more prone to high-temperature incidents but is higher performance as well.