Another interesting article mentions cobalt v alternatives..
Faulty Lithium-Ion Batteries Ground Boeing's Dreamliner: Should EV Drivers Be Concerned? - Translogic
..it's worth noting that the Dreamliner's lithium-ion batteries use different cathode materials than the batteries found on most electric cars. According to Green Car Reports, the cobalt oxide (CoO2) battery chemistry found on the Dreamliner "has the highest energy content, but it is also the most susceptible to overheating that can produce 'thermal events' (which is to say, fires)." The report goes on to note that the only other electric car to use cobalt oxide battery chemistry is the Tesla Roadster, which is no longer for sale.
Boeing's battery problem can be traced back to 2005, when Dreamliner engineering stages were still ongoing. At the time, only lithium-ion cells made of cobalt oxide (CoO2) were deemed air-worthy. Since then, the FAA has approved additional cathodes, including the safer lithium iron phosphate compound (LiFePO4). LiFePO4 batteries are being used by some EV manufacturers like Chinese automaker BYD, who claim their Fe batteries offer "excellent safety performance" because of the material.
Using cobalt oxide (CoO2) as a cathode material has begun to fall out of favor, as lithium iron phosphate, nickel, manganese and other metals have been found to be safer, although cannot offer the same capacity. In all types of battery design, safety is a top priority. Lithium-ion batteries contain safety devices to prevent overheating, but if contaminants enter during production, the safety systems fail.