Nanoscale characterization of the solid electrolyte interphase and lithium growth by atomic force microscopy

The complex growth behavior of lithium (Li) metal has posed significant challenges in gaining an understanding of the operational mechanisms of lithium batteries. The intricate composition and structure of the solid electrolyte interphase (SEI) have added layers of difficulty in characterizing the dynamic and intricate electrochemical processes involved in lithium metal anodes. Real-time observation of Li metal growth has particularly been challenging. Fortunately, atomic force microscopy (AFM) has emerged as a powerful tool, offering invaluable in situ and nanoscale insights into the interface. Its unique contact detection method, remarkably high Z sensitivity, diverse operating modes, and ability for real-time detection during battery operation make AFM a crucial asset. This review aims to comprehensively explore recent advances in AFM application for studying lithium battery anodes. It particularly focuses on examining the formation process and various properties of the solid electrolyte interphase in lithium batteries. In addition, here, we consolidate and evaluate the existing literature pertaining to AFM-based research on the nucleation, deposition, and stripping processes of lithium metal. The objective is to highlight the growth mechanism of lithium metal and elucidate the factors influencing its growth.