Impact modeling of cylindrical lithium-ion battery cells: a heterogeneous approach

Abstract

In this study, a heterogeneous finite element model was developed in LS-DYNA to investigate lateral impact on 6P cylindrical lithium-ion battery cells manufactured by Johnson Controls Inc. The results were compared to those from a homogenized model previously reported by the authors and also experimental data and showed a good agreement. In order to find the stress-strain curves needed for the finite element simulations, compression tests were conducted on stacks of jellyroll's individual layers, i.e. coated aluminum, coated copper and separator. It was found that the load carrying capacity of the jellyroll comes primarily from the coated aluminum layers. SEM images of the separator layers showed their trilayer structure and how they collapse under excessive compressive loads. Compression experiments were also performed on flattened jellyroll samples after being soaked in electrolyte for 24 h. The measured stress-strain relations showed a very good agreement with the results from a similar set of experiments on dry jellyrolls. This suggested that characterizing dry cells could predict how live cells would react under compression/crash tests without dealing with all the safety provisions needed for those experiments.