Impact of particle size distribution on the rest phase behavior of LIB cathodes – Model based analysis

Abstract

Dynamic measurements like the galvanostatic intermittent titration technique (GITT) and other pulse response measurements methods are widely used for the parametrization of battery and electrode models. These methods are based on the analysis of the transient cell potential in response to a change in the current. Most of them focus on the development of the cell potential as a current is applied to a formerly equilibrated cell. On the contrary, the interruption of the current and the development of the cell potential during the rest phase is more challenging to analyze. This is in parts attributed to the non-uniform particle size distributions of electrodes, while many analytical methods rely on the assumption of a single, representative particle size.In this model study, we systematically analyze the impact of non-uniform particle size distributions by means of the extended Doyle-Fuller-Newman model. This is done both by analyzing varying distributions of discrete particle classes and comparing their effects on the voltage relaxation curve. From this, we derive recommendations for a more accurate design of relaxation experiments and provide a framework to interpret frequently observed deviations between electrochemical experiments and reduced order simulations.