Discovery and Development of a Fast Charging Li-Ion Battery

Abstract

Enabling fast charging of Li-ion batteries (LiB) is essential for mainstream adoption of electric vehicles (EVs). A critical challenge to fast charging is lithium plating, which can lead to drastic capacity loss and safety risks. Fundamentally, fast charging is restricted by anode surface reaction kinetics, lithium diffusion in anode solid particles and Li+ diffusion and conduction in electrolyte. In this work, we present an analysis of the contributions of these different physicochemical processes to the total overpotential during fast charging, using an electrochemical-thermal (ECT) coupled model. Special attention is paid to the effect of increasing electrode thickness, a common approach for raising energy density of EV cells, on fast charging capability. It is found that lithium plating is more prone to occur in thicker anodes due to larger electrolyte transport resistance. Furthermore, we present a novel approach of thermal stimulation to enable 10-minutes (6C rate) fast charging of an EV cell with 170Wh/kg energy density.