Elasticity and Size Effects on the Electrochemical Response of a Graphite, Li-Ion Battery Electrode Particle

Abstract

The interactions between electrochemical response, elasticity and particle size of a cylindrical, Li-ion battery, graphite electrode particle is studied. First, a potentiostatic study is conducted to demonstrate the role of higher-order stress terms of the chemical potential on the distributions of flux, stresses and concentrations. Then, two cyclic voltammetry experiments are simulated to study the effects of elasticity on the voltammograms. In the first, the electrode is discharged and then charged, while the second, involves the opposite. Effects of elasticity on the anodic (discharging) portion of the voltammograms are more pronounced in the first experiment when compared to the second. The effects of the elasticity also vary with particle size in different ways for the two experiments. In the first, the effects of stresses on the anodic current increases with particle size and then reaches a plateau at around 30 µm. In the second, a maximum effect of elasticity is seen for a particle size of 5 µm. Our study shows that, stresses induced due to diffusion of Li atoms not only affect the mechanical integrity of the electrode particle, but also change the way the particle responds to an applied external potential, thereby affecting its electrochemical response.