BOEING

Boeing's 787 Dreamliner demonstrates that not all lithium-ion batteries are created equal

Kyle Thibaut
The Federal Aviation Administration has grounded its first passenger airliner since 1979. The new Boeing 787 Dreamliner has had multiple issues leading up to the directive, but the main problem involves the high-tech commercial jet's lithium-ion batteries.

On January 7, a battery overheated and started a fire on an empty 787 at Boston's Logan International Airport. On January 16, an All Nippon Airways Dreamliner had to make an emergency landing because there was purportedly smoke in one of the electrical compartments.

The batteries in question are used as part of backup systems to support major flight controls when the main power fails. But these systems, and their redundant protection systems, failed. That was more than enough to get attention from the feds.

A probe by the National Transportation Safety Board confirmed the aircraft's batteries were at fault, but the notice states uncertainty as to why the batteries are acting up. As of now, speculation surrounds contaminates in the cells and/or manufacturing defects.

But are the lithium-ion batteries used on Boeing's 787 really all that similar to those used in plug-in electric vehicles?

Electric cars have had their share of public battery missteps--most notably when the Chevy Volt and Fisker Karma extended-range electric vehicles were found to catch fire under certain circumstances, prompting investigations. Under high temperatures, lithium-ion batteries can ignite or explode. If one cell short-circuits and overheats, it's possible for the heat to spread and affect other cells.

But, before making a connection between Boeing's battery issues and passenger EVs, 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.

That's why the planes have been grounded. Not only did the batteries overheat, their redundant safety systems didn't kick in.

TRANSLOGIC reached out to Boeing's head of Media Relations, Marc Birtel, and was told that, "[Boeing] has formed teams consisting of hundreds of engineering and technical experts who are working around the clock with the sole focus of resolving the issue and returning the 787 fleet to flight status."