Atomic-Scale Monitoring of Electrode Materials in Lithium-Ion Batteries using In Situ Transmission Electron Microscopy

Lithium-ion batteries (LIBs) are energy storage devices that have received much attention because of their high energy density, high power capacity, and long lifetime. However, even though they are used widely in daily life, their cycling life and safety need further improvement. Understanding the reaction mechanisms and the structural degradation during the lithiation/delithiation process is a prerequisite to further improve the performance of LIBs. In situ transmission electron microscopy (TEM) allows one to monitor structural evolution at the atomic scale in real time, thus providing an unprecedented opportunity to characterize the lithiation reaction pathway in a nonequilibrium state during battery cycling. In this article, the recent advances with respect to elucidating the relationships of dynamic structural evolution, reaction kinetics, and performance of different nanostructured electrode materials at the atomic scale using in situ TEM, based on three representative reaction mechanisms, are described. Specifically, the three systems are intercalation reaction, conversion reaction, and alloying reaction. Based on the advances that have been made, it is expected that in situ TEM will play an indispensable role on future design of LIBs electrode materials.