Characterizing and modeling mechanical properties and onset of short circuit for three types of lithium-ion pouch cells

Three types of lithium ion pouch cells ranging from small consumer electric cells with LiCoO2 cathode to large (electric vehicle size) cells with nanophosphate chemistry were tested under several local and global compression scenarios, including compression between two flat plates and local indentation with a flat cylindrical punch, a conical punch, and three hemispherical punches. Load, displacement, temperature, and voltage were recorded in all tests. The punch displacements were stopped when a drop in force and voltage of the cell, as well as a rise in temperature indicated a short circuit in the cell. Finite element models were developed for each cell type. Two tests were used for calibration of the constitutive properties of each type of cell, and the remaining tests served for the validation of the computational model. The models successfully predicted the load displacement relation and contour of deformations in the cells. Additionally, the models closely predict the force and punch displacement corresponding to the onset of short circuit in the cell. The current results are building confidence in robustness and accuracy of the present calibration and modeling approach.