Effect of graphene nanosheet dispersion on diffusion-induced stresses in layered sn-based nanocomposite electrode for lithium-ion batteries

摘要

An analytical method is proposed to evaluate the diffusion-induced stresses (DISs) in a layered electrode consisting of a current collector and two graphene nanosheet (GNS)-reinforced nanocomposite active plates for lithium-ion batteries. The main focus is placed on investigating the dispersion effect of GNSs within the Tin (Sn)-based nanocomposite active plates on the DISs of the layered electrode. Three types of GNS dispersion, including aligned, randomly distributed, and agglomerated state are considered in the analysis. The effective material properties of the Sn-based nanocomposites reinforced by different GNS volume fractions are predicted using the Mori-Tanaka micromechanical model. It is found that the DISs in the nanocomposite electrodes are very sensitive to the GNS dispersion type. Aligning the GNSs within the Sn-based nanocomposite active plates can reduce the peak stresses in both current collector and active plate. So, from the mechanical viewpoint of designing an electrode, alignment of GNSs within the nanocomposite active plates is an optimized condition. However, agglomeration of GNSs may increase the stress in the whole electrode. Also, the effects of amount and dispersion type of GNSs as well as the thickness ratio of current collector to active plate on the DISs and the curvature of the bilayer Sn-based nanocomposite electrode for the lithium-ion batteries are extensively discussed. Addition and alignment of the GNSs within the Sn nanocomposite active plate can significantly decrease the peak curvature of the bilayer electrode.