Numerical and Experimental Evaluation of a Battery Cell under Impact Load

Impact damage is one of the most critical scenarios for the lithium-ion battery pack of an electrical vehicle, as it involves mechanical abusive loads with serious consequences on electrical and thermal stability. The development of a numerical model for an explicit dynamic simulation of a Li-ion battery pack under impact implies a significant computational effort if detailed models of a single battery cell are employed. The present paper presents a homogenized finite element model of a battery cell, validated by experimental tests of individual materials and an impact test of an entire cell. The macro model is composed of shell elements representing outside casing and elements with a homogenized and isotropic material for the jelly roll. The displacements and deformed shape of the numerical model of the battery cell were compared with those measured on real test specimens; full-field optical scanning was employed to reconstruct the 3D shape of the deformed battery. The overall deformation of the simulation and experimental results are comparable with a deviation of the maximum intrusion of 14.8% for impact direction and 19.5% for the perpendicular direction considering the cumulative effects of simplifying hypotheses of the numerical model and experimental side effects. The results are a starting point for future analyses of a battery pack and its protection systems under impact. The model presented in this paper, considering the low computing power needed for calculation and acceptable mesh size for crash, should be able to be used in bigger resources consuming crash simulation models. In this way, the cells' deformation and behavior can be tracked more easily for safety management and diagnosis of the crashworthiness of the packs or car batteries.