In situ transmission electron microscopy study of individual nanostructures during lithiation and delithiation processes

Direct observation of the nanostructural evolution of electrode materials is critical to understanding lithiation and delithiation processes during cycling of batteries. Due to its real-time monitoring and high spatial resolution, in situ transmission electron microscopy (TEM) plays an important role in understanding the reaction mechanism and dynamic processes in battery materials. This paper reviews the recent progress in using in situ TEM to study individual nanostructures in battery materials using an open-cell design, including for anode materials and cathode materials in lithium ion batteries, and Li-S batteries. Through in situ TEM, the fundamental science and reaction mechanisms, including phase transformations, electrode degradation, size effects, evolution of a solid electrolyte interphase (SEI) and nanostructures, and electrolyte decomposition of nanomaterial-based electrodes were observed during lithiation and delithiation processes. These characteristics will be very useful to the development of basic guidelines for the rational design of high-performance batteries. Finally, the challenges and perspectives of observing individual nanostructures using in situ TEM during electrochemical processes still need to be discussed and addressed.