Probing of Internal Short Circuit in Lithium-Ion Pouch Cells by Electrochemical Impedance Spectroscopy under Mechanical Abusive Conditions

Though lithium-ion batteries (LIB) are becoming prevalent energy storage systems for electrifying vehicles, their high energy density often makes them susceptible to various thermal instability problems. Also, due to the battery abuse that can barely be avoided and as LIBs are exposed to many accidents, mechanical damage of different intensities often facilitates internal short-circuiting of the components and leads to thermal runaway events. Herein, we demonstrate resistance measurement by electrochemical impedance spectroscopy (EIS) as a tool for the detection of an internal short circuit (ISC) and health monitoring in LIBs. The changes in the EIS at different mechanical deformation levels are evaluated through a proper equivalent circuit model. The fitted results reveal that the cathode-electrolyte interface resistance can be used to predict the onset of ISC due to the mechanical abusive conditions. Changes in the EIS are traced to the battery deformation levels or local strain changes due to the internal damage leading to ISC. The obtained results demonstrate that impedance spectroscopy provides information about the emergence of ISC and battery health.