The origin of the superior fast-charging performance of hybrid graphite/hard carbon anodes for Li-ion batteries

Abstract

Hybrid anodes formed by blending graphite and hard carbon have been demonstrated to be an effective method of overcoming the inherent tradeoff between the energy density and fast-charging capability for Li-ion battery electrodes. However, owing to the complex interplay between the constituent active materials, a fundamental understanding of the electrode parameters that enable the fast-charging performance in hybrid anodes has remained elusive. Such understanding is crucial for an effective electrode design. In this work, we employ continuum-scale modeling and analyze the results using the regression tree algorithm and the second Damköhler number to quantify the impact of material and electrode properties on the SOC achieved at the anode voltage of 0 V vs. Li/Li⁺. Our results show that the effective electrolyte transport properties of Li ions and the open circuit voltage profiles of the active materials are two key parameters that determine the fast-charging (4C) performance of the hybrid anode.