Deformation of lithium-ion batteries under axial loading: Analytical model and Representative Volume Element

Abstract

Using lithium-ion batteries requires an understanding of their deformation and failure under mechanical abuse. Properties of batteries under through-thickness loading has been the subject of various studies over recent years, however, in-plane properties are not yet fully understood. In-plane loading can lead to buckling, short circuit, or failure of connecting tabs. In this research, parameters controlling the in-plane deformation of cells are investigated, first by an analytical approach, then by a computational model of the cell’s Representative Volume Element (RVE). Analytical results show that cell lengths larger than the buckling wavelength do not affect the buckling strength thus allowing experimental results on a small specimen of the cell to be used for buckling analysis instead of expensive full cell testing. Computational models show that the RVE can be used to extract homogenized anisotropic material properties of full cells. Models of full cells calibrated from the analytical estimates and RVE were validated against experiments and show the efficiency of the approach, providing a tool for simulation of battery failures and designing efficient protective structures.