Microscopic electrochemical analysis of all-solid-state Li-ion batteries using conductive atomic force microscopy as a nano current collector probe

Abstract The high ionic/electronic resistance at the solid/solid interfaces of all-solid-state Li-ion batteries (LIBs) is a critical challenge that limits their practical application. High-resolution analytical methods are required to investigate the local electrochemical properties of the interfaces. In this study, we applied conductive atomic force microscopy (c-AFM) to all-solid-state LIBs consisting of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) as the active material and a sulfide-based solid electrolyte (SE). The NCM positive electrode was observed by applying a bias voltage between the c-AFM tip and the negative electrode. In this operation mode, denoted as the “nano current collector” (NCC) mode, the AFM tip functioned as a nanoscale current collector. The oxidation currents at the NCM/SE interface and grain boundaries inside the NCM particles were successfully detected in this mode at a spatial resolution of >100 nm. c-AFM performed in the NCC mode enhanced the spatial resolution for the analysis of electrochemical phenomena in all-solid-state LIBs.