Trial by fire: Boeing should have chosen a safer type of Lithium-ion battery chemistry for its 787
Potential cost savings and more demanding electrical loads are pushing airliners like the Boeing 787 towards lithium-ion (Li-ion) batteries. However, according to Lux Research, the type of Li-ion battery chemistry must be carefully chosen and well-managed. Failure to do so may result in serious safety issues.
On January 7, a 787’s Li-ion battery caught fire while the airplane was parked. Then, on January 16, another suspected 787 Li-ion fire forced an emergency landing. The Li-ion batteries in question are supplied by Japanese battery manufacturer GS Yuasa. Lux Research analyzed the Boeing 787 battery specifications and found the following:
Boeing did not choose the safest battery type.
The 787’s batteries use a material known as lithium cobalt oxide (LCO), which imparts excellent energy density. However, there are known LCO safety concerns, most notably that the material does not resist overheating well. Once started, Li-ion fires typically generate oxygen and are very difficult to extinguish: The first 787 battery blaze took 40 minutes to snuff out, injured one firefighter, and damaged the airplane’s equipment bay.
Boeing should switch to a safer cathode material. In choosing LCO, Boeing eschewed safer alternatives such as lithium iron phosphate (LFP). Even when overcharged, LFP changes only slightly in structure, preventing oxygen release and resisting thermal runaway. This decision is all the more shocking considering major automakers early on refused to entertain the possibility of using LCO in passenger vehicles due to safety concerns.
Regulatory changes should be expected. In the wake of this incident, Lux Research expects the U.S. Federal Aviation Administration (FAA) to tighten its Li-ion regulations, airplane makers to move towards safer cathode chemistries like LFP, and opportunities to arise for more sophisticated battery management and safety systems.
Boeing’s reputation has taken a major hit, and it must invest considerable funds to prove the safety of the aircraft to anxious regulators. Shortly after the incident, the FAA grounded all U.S. 787s, and started a review of the airplane. Furthermore, GS Yuasa has felt the ramifications of the widespread attention surrounding the 787, losing over 5% of its stock value in a single day.
The underlying cause of the Boeing fires is still unknown. Though there may be faults elsewhere in the system electronics, the fact remains that LCO is inherently at risk of undergoing thermal runaway, exacerbating problems that may arise elsewhere in the system. “Boeing made a design decision favoring higher energy over safer options, and is now paying the price,” said Cosmin Laslau, Lux Research Analyst.
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