Progress Toward Understanding Catastrophic Failure of Electric Vehicle Li-Ion Batteries: Multi-Physics Modeling

The goal of this work is to enhance understanding of critical design aspects that would prevent automotive lithium-ion battery packs from catastrophic failures. Modeling lithium-ion batteries is a complex multiscale multi-physics problem. The most dangerous energy producing component of a lithium ion cylindrical cell, jellyroll, is a layered spiral structure, which consists of thin layers of electrodes and separator only microns thick. In this study, we investigate the feasibility of using commercial explicit finite element code LS-DYNA to understand the structural integrity of lithium-ion batteries subjected to crushing condition through computer simulation. The jellyroll was treated as homogeneous material with an effective stress-strain curve obtained through characterization experiments of representative jellyroll samples and individual electrode layers. Physical and numerical impact tests have been conducted on cylindrical cells using developed drop test system. Results of material homogenization, experimental drop testing, and initial structural simulations are discussed. The investigation of structural cell deformations coupled with thermal heat generation and distribution after the crash brings us one step closer to accurate modeling of the entire battery pack that consists of hundreds of cells.