Influence of Current Density on Graphite Anode Failure in Lithium-Ion Batteries

Abstract

© The Author(s) 2019. Published by ECS. Safety and durability are major challenges for commercial lithium-ion batteries (LIBs), especially those used in electric vehicles and large-scale energy storage systems. Herein, we investigate the reliability and degradation behavior of graphite anodes using a LiFePO4||graphite three-electrode pouch cell. The electrochemical impedance spectroscopy (EIS) and assisted scanning electron microscopy (SEM) results demonstrate the presence of an uneven solid electrolyte interphase (SEI) that grows with prolonged cycling at currents rate greater than 1 C. In addition, we provide a direct way to visually detect metallic lithium deposition on graphite anodes by energy dispersive X-ray (EDX) spectroscopy. The three-electrode potential and EDX analyses indicate that metallic lithium deposition begins only after 100 cycles at 1 C, leading to capacity decay and the safety issue of LIBs. Evaluating the characteristics of graphite anodes in rechargeable batteries will provide straightforward guidance for the development of commercial LIBs.