Mechanical Characterization of Li-ion Batteries in Abusive Loading Conditions

As the aerospace industry furthers development into long term missions in often remote regions, a consistent supply of power has become a niche that batteries, most commonly lithium-ion batteries (LIBs), have dominated in recent years. Due to the high volatility and relatively unpredictable nature of LIB combustion, which can have catastrophic consequences for aerospace vehicles if left unchecked, recent development in the industry have been oriented around containment and mitigation of these events. Prediction of these failures has proven unreliable as degradation of battery performance and safety has shown to be complex with coupled thermal, electrochemical, mechanical and environmental variables. To investigate the effect of mechanical abuse on these cells, LIBs were impacted with dynamic mechanical loading and changes in their electrochemical performance in the short, medium and long term were monitored. Through this we characterized trends in experimental battery performance which allowed us to predict degree of damage and safety levels within cells. Further structural analysis and thermal abusive testing were performed on failed cells to allow for a better understanding of the leading mechanisms of cell failure and long term consequences for sudden mechanical abuse. Using this knowledge, Multiphysics modeling frameworks were developed to predict both sudden and long term failure modes of LIBs subject to mechanical impact, and protocols were developed to determine degree of internal damage utilizing live electrical prognosis techniques. Additional models are proposed which consider mechanically abusive conditions and damaged internal structure in long term safety determination of LIBs. Through this investigation additional insight can be taken when developing battery packs considering protection from inciting incidents and operando safety analysis to considerations of long term battery health given extreme conditions.