Multi‐scale modelling of the tensile behavior of lithium ion battery cellulose separator

Abstract

AbstractAs a satisfactory green material for a lithium ion battery separator, cellulose possesses better wettability and superior thermal and chemical stability compared to commercial polyolefin separators. The macroscopic mechanical properties of the separator are determined by structural parameters on different dimensional scales. In this paper, a two‐scale modelling method is proposed for a cellulose separator. At micro‐scale, a single fiber structural model was established with a cross‐sectional profile extracted through image processing, combined with the fiber helix angle. At meso‐scale, a representative volumetric element model and a two‐dimensional random fibrous model for the fibrous network of the cellulose separator were developed. The elastic modulus in the machining direction (MD) and transverse direction (TD) of the two models were calculated by finite element simulation and compared with experimental data. The results show that the elastic modulus of the models is slightly larger than that from experiments. Compared to experiments, the relative errors in the MD and TD of the representative volumetric element model are 2.80% and 6.78%, respectively. The relative errors in the MD and TD of the two‐dimensional random fibrous model are 6.70% and 8.47%, respectively. Consequently, multi‐scale modelling is proven to have considerable value in investigating the properties of fibrous materials. © 2019 Society of Chemical Industry