Earlier this month, one of the fuel-efficient passenger jet’s lithium-ion batteries caught fire while the airplane was parked, and another suspected battery fire on January 16 forced an emergency landing. By the following day, governments in the US, Japan, India and Europe had grounded the planes.
The underlying cause of the Boeing fires is still unknown. But Lux says the Dreamliner uses a high-energy battery inherently at risk of thermal runaway, and should switch to an alternate type of lithium-ion battery.
Boeing would not say whether it agreed with the research firm’s assessment, stating only, “We are supporting the investigations that will determine the cause of the recent incidents involving 787 batteries. Until those investigations conclude, we can’t speculate on what the results might be.”
In a January 16 statement, Boeing chairman, president and CEO Jim McNerney said the safety of 787 passengers and crewmembers remain the company’s top priority, adding, “We are confident the 787 is safe and we stand behind its overall integrity.”
Lux says otherwise.
According to the analysis, the Dreamliner’s lithium-ion battery, supplied by Japanese battery manufacturer GS Yuasa, is not the safest battery. It use a material called lithium cobalt oxide (LCO), which imparts excellent energy density — but has several known safety concerns. The material does not resist overheating well.
Lux says once started, Li-ion fires typically generate oxygen and are very difficult to extinguish. But while some Li-on batteries start to break down at over 300 degrees C, LCO can break down at as low a temperature as 175 degrees C, which seriously lowers the battery’s safety margin, according to Lux analyst Cosmin Laslau.
The first 787 battery blaze took 40 minutes to snuff out, injured one firefighter, and damaged the airplane’s equipment bay.
Lux says major automakers early on refused to even consider using LCO in passenger vehicles because of safety concerns, and recommends Boeing switch to a safer cathode material such as lithium iron phosphate (LFP). Even when overcharged, LFP changes only slightly in structure, preventing oxygen release and resisting thermal runaway.
In the wake of this incident, Lux says it expects the US Federal Aviation Administration to tighten its lithium-ion regulations and airplane makers to move towards safer cathode chemistries like LFP.