MECHANICAL ABUSE MODELING OF LITHIUM-ION BATTERIES WITH ELECTROCHEMICAL COUPLING

Abstract

Electric vehicles contain hundreds of high-energy density lithium-ion batteries. The crashworthiness of these vehicles can be improved by better understanding the response of these batteries in an event of an accident or abusive loads. These loads can induce short-circuit and thermal runways in extreme cases. Therefore, an efficient finite element model of a battery that can precisely predict the coupled multi-physics behavior of a cell in a real-world application is desired. This investigation incorporates detailed and homogenized multi-physics modeling of various form factors of lithium-ion batteries. In the first two chapters of this thesis, a multi-physics homogenized model of a pouch cell was developed and validated in a wide range of multi-disciplines of the battery. In contrast to other similar models described in the literature, which are only applicable in certain scenarios, this model has a much broader range of applications due to the innovative techniques developed for material calibration and cell modeling. In addition, due to the homogenized nature and computational cost efficiency of this technique, the developed model has significance in the crashworthiness analysis of battery packs and electric vehicles where hundreds of these batteries exist. In the final chapter, a detailed layered model of an 18650 cylindrical cell was developed. Component and cell-level tests were performed on the cell to calibrate the material properties and extract the geometries of all the components of the cell. This model is the first of its kind that precisely predicts the load-displacement response and shape of deformation in various loading scenarios. This developed model has crucial importance in the safety assessment of the batteries by providing insight into the sequence of deformation of the internal layers and components and their interplay during mechanical abuse loadings. Overall, the two developed models in this thesis provide battery-related industries with a tool to improve the safety of future electrified industries.