Enhanced Rate Performance in Electrode Materials for Lithium-Ion Batteries

Abstract

Lithium-ion batteries are dominating the field of energy storage and have already started to enter the electric vehicle market. This market is striving for better electrochemical performance, such as higher specific energy and energy density, longer lifetime and improved safety. In order to fulfil these challenges, the exploration of new materials is usually preferred. Through this study we prove that electrode design using established anode chemistry is a powerful tool to enhance the performance of Li ion batteries. One of the main limitations of current batteries lies in the transport of lithium ions, especially at high cycling rates and in high loading electrodes. This shortcoming does not arise from the insertion/extraction kinetics within the bulk active particles [1] but from the slow diffusion of lithium ions across the electrode. In particular, reduction of the tortuosity would accelerate such rate-limiting transfer process [2]. Minimising the ion and electron path tortuosity within thick electrodes would lead to batteries capable of sustaining higher cycling rates and power densities. We used a combination of electrochemical measurements, 3D imaging and diffusion modelling by Finite Element Analysis to study the charge carrier transport properties in architectured electrodes. Through this presentation we will show that advanced electrode engineering can be used to greatly improve the electrochemical performance of anodes for lithium-ion batteries. Tortuosity of electrode materials is significantly decreased in favor of higher specific charges (up to three times) at high cycling rates.