Deformation and Failure Behavior of Cylindrical Lithium-Ion Batteries Subjected to Mechanical Loading

It is of critical importance to understand the failure behavior of Lithium-ion batteries subjected to mechanical loading order to improve crash safety of electric vehicles. The deformation of battery pack during collision/crash results in catastrophic events and thus it becomes necessary to study the failure of the battery during such scenarios. The goal of this research was to understand the mechanical and electrical failure characteristics of cylindrical Lithium-ion cells subjected to deformation. This paper discusses on experimental investigations on material failure in the electrode assemblies i.e. the jellyroll of Li-ion batteries after mechanical loading which eventually leads to electrical failure, short circuit and at times violent thermal runaway scenarios. Experiments were carried out on NCA chemistry 18650 cylindrical cells under various loading conditions in a custom designed fumehood which capture the various failure modes of the cell in a module or a battery pack in crash events. The loading conditions include, compression between two flat plates in horizontal and vertical terminals orientations, lateral indentation by a cylindrical rod, hemispherical punch, flat circular punch and three-point bending. The understanding of mechanical abuse induced short circuit behavior of Li-ion cells will aid in further development of battery crash models thereby optimizing battery pack development cycle for xEV applications.