A universal anisotropic model for a lithium‐ion cylindrical cell validated under axial, lateral, and bending loads

Abstract

Li‐ion batteries are widely used in electric vehicles (EVs) propulsion. Therefore, ensuring their safety under mechanical abuse and accidental loads is a major challenge for the industry. To get a better understanding of the battery behavior in such cases, material calibration and computational modeling of the battery cells are essential. This paper aims to develop a universal homogenized model for an 18,650 cell that can predict cell behavior under both axial and lateral loading cases as well as three‐point bending. Previous homogenized models presented in the literature have covered one or two of these cases, but none have been validated in all these three major loading scenarios. To achieve this, precise shell casing and jellyroll material calibrations were performed. The features included in this universal model are (I) uncoupled calibration of axial and lateral properties for the cylindrical jellyroll from experiments performed in these two loading directions and employment of an anisotropic crushable foam model to simulate these features, (II) using Hill's anisotropic yield criteria and modified Mohr–Coulomb fracture criteria for the shell casing. The universal model developed here was able to predict the response of the cell in all lateral, axial, and bending loading scenarios. A comparison of this model with the previously developed isotropic models shows the special advantage of the new model in cases of axial loading and bending. However, for lateral compression cases, even the isotropic model provides a very close prediction. The experiments used for this study were all performed on fresh discharged cells under quasi‐static loading.

Homogenized characterization of cylindrical Li‐ion battery cells using elliptical approximation

“…The thickness of the casing was 0.25 mm, its outer radius was 9 mm, and the total length of the battery was 65 mm. Material model 122 of LS‐DYNA library (Hill 3R model) was used to model the shell casing, with parameters and hardening curves calibrated according to Song et al and Zhang and Wierzbicki 42,43 . The transverse crush model was developed by setting up a stationary rigid wall underneath the battery model while a rigid plate was crushing the battery from the opposite side at a constant velocity.…”

Modeling Electric Vehicle’s Battery Module using Computational Homogenization Approach

“…In this work, material properties from the literature explained below are used to define the properties of the parts in the RVE. Song et al [55] determined the averaged mechanical properties of the jellyroll of an 18650 cell in transverse and axial directions. The specifications and properties are listed in Tables 2 and 3, respectively.…”