Li-ion battery safety under aircraft simulated speed impact:Risk and mitigationOA

Lithium-ion batteries(LIBs)play a critical role in the early adoption of small,electrified aircraft by providing the required energy,power,and cycle life.However,safety is still a concern,especially in dangerous situations such as aircraft crashes or operations in harsh conditions.If damaged,the battery can release stored energy rapidly,leading to rapid chemical decomposition and possible battery fire,known as a thermal runaway(TR).Despite their critical role,limited information is available in the open literature about LIB behavior when installed in electric aircraft powered by LIB that crashes into hard surfaces such as steel,concrete,wood,or even soft objects like sand or water.Herein,we present the crash survivability of LIB cells when launched into a rigid steel surface with speeds ranging from 50 to 300 miles per hour(mph).At 300 mph,all bare pouch LIB cells shattered into pieces,whereas cylindrical cells either caught fire or were severely damaged.At 120 mph,all bare pouch cells caught fire while cylindrical cells flattened and lost voltage due to electrolyte spillage.Bare cells tested at 50 mph survived the impact with slight visible cell deformation.As a mitigation strategy,sheets of metals and carbon composites,were used as shock absorber to protect cells.It was found that a 1 mm thick titanium sheet can protect cells from a crash into steel at speeds>150 mph and a 2 mm titanium sheet can protect cells from a crash at 200 mph.We have proposed a notional battery packaging design based on the preliminary high-speed impact data.The data presented herein is encouraging.However,rigorous research may be needed to find protective materials that can provide adequate crash safety—both mechanical and thermal—from cell to module to pack level,upon impact when aircraft speeds reach or exceed 500 mph if the crash is otherwise survivable or unmanned.