Prevention of Dendrites on Graphite By K⁺ Cation Addition to Electrolyte

Abstract

With the ever-increasing demand for energy, one of the biggest challenges with Lithium ion batteries (LIB) is to enable the fast charging capability for automotive electrification. However, graphite, the most common anode material for LIB cannot fully accommodate fast charging and provokes safety issues such as lithium plating and subsequent dendrite growth. This could lead to an internal short circuit, which can result in a fire in the battery. In this work, a systematic study has been performed with various concentrations of KPF6 salt addition to electrolyte in order to understand the effect of salt additives on dendritic growth in graphite anodes. K ions easily deposit on defect sites present on graphite particles, confirmed by secondary electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy detector (EDX). This prevents the dendrite formation by restricting the incoming Li ions even at 2C-rate (corresponding to 5.52mA) cycling, which was observed by SEM imaging. After close inspection, it concluded that, the KPF6 modified electrolyte is very much beneficial in inhibiting dendritic morphology without forming SEI products (confirmed by X-ray photoelectron spectroscopy; XPS). Moreover, there were no observable adverse effects on the electrochemical properties, such as capacity, ionic conductivity and resistance of the cell.