Mechanical Deformation of Lithium-Ion Pouch Cells under in-plane Loads-Part II

Abstract

Based on the experimental observation, pouch cells can withstand severe deformation during fully confined in-plane compression with flat punches without any risks of a short circuit. During the deformation, the structuralbehavior is characterized by regular kinks, buckles, and shear bands. This study aims to provide a modeling approach for the in-plane compression on lithium-ion pouch batteries in a fully confined case with a flat punch. To capture the right mechanism of buckling while maintaining a satisfactory computational efficiency, two approaches are proposed: a homogenized model with imperfections and an enhanced homogenized model with equivalent layers of metal foils. The first approach introduces periodic geometrical imperfections with a wavelength as observed in the experiments. The second one creates a model in between the homogenized model and detailed model with equivalent properties of coating materials and metal foils. It is concluded that the introduction of imperfections could not correctly capture the folding mechanism, while with the latter hybrid approach, it is possible to capture the right progressive folding pattern of the battery cells during the in-plane compression test. Different potential approaches of the simulation model are investigated for obtaining a better agreement of the prediction and the measured experimental load-displacement response.