Phantom Battery Pack for Destructive Testing of Li-Ion Batteries

The objective of this study is to find a structural alternative to jellyroll in order to safely conduct experimental crash testing of lithium-ion battery packs in academic laboratory environment. A procedure for lateral impact experiments has been developed and conducted on cylindrical cells and phantom cells using a flat rigid drop cart in a custom-built impact test apparatus. The main component of a cylindrical cell, jellyroll, is a layered spiral structure which consists of thin layers of electrodes and separator material. We investigate various phantom materials — candidates to replace the layered jellyroll with a homogeneous anisotropic material. During our experimentation with various phantom cells, material properties and internal geometries of additively manufactured components such as in-fill pattern, density and voids were adjusted in order to develop accurate deformation response. The deformation of the phantom cell was characterized and compared after impact testing with the actual lithium-ion cells. The experimental results were also compared with explicit simulations (LS-DYNA). This work shows progress toward an accurate and safe experimental procedure for structural impact testing on the entire battery pack consisting of thousands of volatile cells. Understanding battery and battery pack structural response can influence design and improve safety of electric vehicles.